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S0021967319309471 | An untargeted and pseudotargeted metabolomic combination approach was developed to identify reliable and stable differential markers which can distinguish between pork meat from live pigs conventionally butchered and pork meat from dead pigs butchered immediately after death from diseases or other abnormalities . In this study 24 differential metabolites of interest were screened by the UHPLCTripleTOFMS based untargeted metabolomic method and 14 differential markers were detected by the UHPLCQTRAPMS based pseudotargeted metabolomic method after performing statistical analysis to remove false positive differential metabolites . Among the possible differential markers identified using the Metlin database and references were carnosine | Metabolomics for distinguishing live from dead pork meat was firstly developed. Untargeted and pseudotargeted metabolomics determined 14 differential markers. Some differential markers were identified as carnosine. carnitine. histidine. Approach was accurate in quantification to exclude the false positive metabolites. Developed approach would be applied to evaluate the quality and safety of foods. |
S0021967319309483 | Therapeutic antibodies can elicit an immune response through different mechanisms either cell independent via complement activation or through activation of immune effector cells . After target binding the Fc part of the antibody will interact with Fc receptors on the surface of effector cells leading to activation and lysis of the target cells by a mechanism called antibody dependent cell mediated cytotoxicity . The ADCC of an antibody can be increased by modifying the carbohydrates on the Fc part . If the fucose on the first | Fully fucosylated mono fucosylated and a fucosylated IgGs were separated. Mono and a fucosylated IgGs had equivalent biological activity. Relative peak area of FcRIIIa chromatography correlated to fucose content. High throughput label and modification free screening of IgG producing clones. |
S0021967319309501 | Several issues are associated with the use of high performance liquid chromatography diode array detector analysis in the evaluation of the chemical equivalence of traditional Chinese medicine such as the choice of representative wavelengths quick and efficient integration correct matching of different components and full use of spectral information . These problems can be addressed by handling raw three dimensional data in a different manner which led to the development of the spectral and chromatographic overall analysis method . In SCOA the Whittaker smoother is used to eliminate the baseline drift caused by solvents and the projection profiling is extracted from 3D data as the most informative chromatogram . Peak matching takes advantage of spectral similarity to exclude spectrally dissimilar components in the matching group . Subsequently the exponential Gaussian hybrid function is used to fit and integrate the projection profiling thus avoiding the cumbersome and time consuming integration process . Two data sets were used to validate and demonstrate the SCOA . The results show that the SCOA is more comprehensive and reliable than HPLC DAD analysis in the chemical equivalence assessment of TCM . | A data handling technique targeted at raw data generated by HPLC DAD. Projection profiling was used to improve the chromatographic information extraction. All of the peaks were verified using the spectral similarity and peak purity. The solvent noise was eliminated using a Whittaker smoother. A computer based strategy to evaluate the similarity of traditional Chinese medicine. |
S0021967319309513 | Biomass burning emissions are a significant source of particles to the atmosphere especially in the Southern Hemisphere where the occurrence of anthropogenic and natural wild fires is common . These emissions can threaten human health through increased exposure whilst simultaneously representing a significant source of trace metals and nutrients to the ocean . One well known method to track BB emissions is through monitoring the atmospheric concentration of specific monosaccharide anhydrides specifically levoglucosan and its isomers mannosan and galactosan . Herein a new method for the determination of levoglucosan and its isomers in marine and terrestrial aerosol samples is presented which delivers both high selectivity and sensitivity through the coupling of ion chromatography and triple quadrupole tandem mass spectrometry . Optimal chromatographic conditions providing baseline separation for target anhydrosugars in under 8min were obtained using a Dionex CarboPac | An IC TSQ MS method was developed for the analysis of biomass burning BB markers. BB markers LODs are the lowest reported up to date for an IC MS method. First use of lithium cationisation for BB markers analysis in aerosol samples. Method applicability demonstrated analysing 40 atmospheric samples. Acid washed W41 cellulose filters shown as suitable for BB markers sampling. |
S0021967319309537 | Mussel inspired polydopamine based materials are attractive as stationary phase for open tubular capillary electrochromatography due to their many fascinating properties . However all of the existing strategies for fabricating PDA based OT CEC columns are limited in aqueous solutions . Consequently it is a challenge work to directly immobilize the hydrophobic functional materials onto the inner wall of PDA modified capillary . Herein by using the organic amine inducing co deposition strategy a novel preparative method was developed for in situ one pot synthesis of PDA octadecylamine co deposited coating inside capillary as OT CEC stationary phase . The formation and morphology of the PDA ODA co deposited coating were characterized by field emission scanning electron microscopy atomic force microscope attenuated total reflectance Fourier transform infrared spectroscopy and contact angle measurements . The separation performance of the fabricated PDA ODA modified columns was validated by the separation of alkylbenzenes and steroids which could achieve baseline separation with high separation efficiency . Their separation was found to follow the reversed phase chromatographic retention mechanism . The co deposited column showed good stability and long lifetime . The repeatability of the PDA ODA co deposited column was also evaluated with the relative standard deviations for intra day and inter day runs less than 5 and column to column runs less than 6 . | A novel PDA ODA co deposited capillary column was developed. ODA was one step immobilized in PDA modified column via organic amine inducing co deposition. The tested analytes were well separated on the PDA ODA co deposited column. The PDA ODA co deposited capillary exhibited great stability and repeatability. |
S0021967319309550 | This work investigates the applicability of on line extraction directly coupled to liquid chromatography for the dynamic extraction of hydrophobic organic compounds from complex solid samples . The method operates within the existing apparatus of the LC by replacing the valve loop with an extraction vessel comprised of an empty guard column loaded with the sample . In this manner extraction is accomplished by the mobile phase as it flows through the extraction vessel under high pressure without the need for additional apparatus other than those comprising the LC system or additional sample pretreatment steps . The experimental parameters affecting the extraction efficiency of the method were investigated and discussed in relation to both the extraction performance and the chromatographic efficiency . The method was optimized and applied for the first time to the extraction of hydrophobic UV filters from spiked soil and sediment samples yielding recoveries between 59 and 117 and reproducibility from 4.8 to 14.3 which are comparable to those reported from more advanced sample preparation methods . | OLE LC is applied to the extraction of hydrophobic compounds in complex samples. Optimization of chromatographic and extraction conditions is described. Some technical aspects of OLE LC are elucidated. Quantification of UV filters in soils and sediments is demonstrated. |
S0021967319309562 | A wide pore diphenyl stationary phase was evaluated for the analysis of monoclonal antibodies comparing a conventional mobile phase of acetonitrile water containing overall 0.1 trifluoracetic acid with a similar mobile phase incorporating in addition 5 butanol . Alternatively TFA was replaced by ammonium formate buffer and by methane sulfonic acid . Addition of 5 butanol to the mobile phase reduces the minimum temperature at which suitable UV analysis of the mAbs can be obtained from about 70C with TFA alone to about 60C thus potentially improving column lifetime and reducing the possibility of sample degradation . AF buffers produce satisfactory UV sensitivity at 70C and have the advantage of reducing signal suppression in mass spectrometry . Some peak tailing was noted in comparison with TFA separations . Methane sulfonic acid at the same molar concentration as TFA produced the best chromatographic peaks maintaining reasonable UV sensitivity down to 50C also giving acceptable results even at only 3mM concentration of the additive . The good results with this additive were attributed to its stronger acidity and consequent suppression of the ionisation of column silanols . Surprisingly peak response was rather poorly correlated with the peak capacity of the gradient analysis . A possible explanation is self deactivation of active column sites by a portion of the sample . | Diphenyl bonded 1000 column evaluated for separation of monoclonal antibodies. Rituximab and Bevacizumab selected as difficult probes. Column was tested with trifluoroacetic acid and a variety of additives. Ammonium formate is mass spectrometer friendly with acceptable results at 70C. Methanesulfonic acid gives best peak capacity and reasonable results at 50C. |
S0021967319309574 | Modified micellar liquid chromatography with a natural deep eutectic solvent produced from choline chloride and ethylene glycol was employed for melamine monitoring in milk matrix . This sustainable mobile phase was attained through chemometrical optimization of crucial variables including concentration of sodium dodecyl sulphate along with volume percentages of both NADES and glacial acetic acid . The desirability function and central composite design were utilized as chemometrical tools . Retention time t | Introducing a sustainable mobile phase for melamine monitoring in milk samples. Great performance of natural deep eutectic solvent as the chromatographic modifier. Efficient chromatographic retaining of melamine in short analysis time. Melamine analysis in milk samples without any interfering with coexisting proteins. Melamine quantification without tedious sample preparation steps. |
S0021967319309586 | A metal organic framework material MIL 101 was developed as an effective solid phase extraction adsorbent for the extraction of eleven UV filters compounds . The MIL 101 adsorbent was packed into a polypropylene cartridge and connected at the outlet tip with the Visiprep vacuum manifolds allowing process up to 12 port SPE samples simultaneously . The extracted UV filters were quantified by gas chromatography tandem mass spectrometry . Several parameters affecting the extraction efficiency of the target analytes i.e . desorption conditions sample pH the addition of salt and sample volume were optimized by ANOVA analysis followed by a multifactorial design . The sample breakthrough volume of the developed method was also evaluated . The SPE GCMS MS method was validated in terms of linearity | Multiclass UV filter analysis in environmental and recreational waters by SPE GCMS MS. MIL 101 is proposed for the first time as a miniaturized on column SPE adsorbent. The extraction procedure was extensively optimized by experimental design. Good recoveries precision and low LOD at the ngL. were achieved. Real water analysis showed method accuracy as well as high occurrence of UV filters. |
S0021967319309598 | One of the main steps in designing preparative chromatographic separation units is the selection of a well performing adsorbent . This is often based on expert knowledge or based on case studies of preselected adsorbents . Therefore the selection is usually limited in terms of an optimised choice . In this contribution a model based optimisation of the selection of an adsorbent on the basis of correlations between structural adsorbent properties with model parameters of a transport dispersive model is proposed . Model parameters of glucose and xylose for five cation exchanger resins with varying degree of cross linking are experimentally determined in a sequential approach . Void fractions and particle porosities were determined by pulse experiments with different tracers . Single component isotherms were determined threefold via breakthrough curves with concentrations of up to 250gl | Mathematical correlations between structural resin property and model parameters. Model based prediction of an optimal degree of cross linking. Novel method to include the chromatographic system in optimisation algorithms. |
S0021967319309604 | Analysis of acrylamide in coffee by liquid chromatography tandem mass spectrometry is prone to interferences . According to our study unknown background ions can entail an overestimation by up to 40 in case of coelution with acrylamide . In order to develop a precise and accurate quantification method for acrylamide identification and removal of these interfering ions is requested . We thus studied potential isobaric impurities of acrylamide using liquid chromatography high resolution mass spectrometry . An in source fragment of | Acetyl alanine was identified as an interference of acrylamide in coffee. An in source fragment of. acetyl alanine is interfering with acrylamide signal. Overestimation can reach 40 if acrylamide coelutes with. acetyl alanine. Mobile phases without modifier allow an interference free acrylamide analysis. |
S0021967319309616 | Qualitative and quantitative determination of volatile markers in aqueous based fragrances assumes ever increasing importance because of both the need for quality control and the safety regulatory limitations introduced for several compounds . This study reports and critically discusses the results of applying new water compatible ionic liquid GC stationary phases based on phosphonium and imidazolium derivative cations combined with trifluoromethanesulphonate to the direct quantitative analysis of aqueous samples in the perfume field with GCMS . Narrow bore columns of different lengths especially prepared for this study were adopted to minimize the amount of water reaching the MS detector after GC separation . All GCMS analysis steps were investigated to achieve results compatible with quality control requirements for the volatiles of interest in this field in terms of LODs LOQs and repeatability . Reliability of the GCMS results was demonstrated by determining volatile allergens in two commercial perfumes as per EU regulations concerning no declaration limits for leave on and rinse off cosmetic products . | Direct GCMS quantitative analysis of aqueous samples with water compatible columns. Injection conditions were optimized to obtain reliable and repeatable results. Narrow bore columns were adopted to minimize the amount of water in the MS. Reliability of the results was proved by determining volatile allergens in perfumes. |
S0021967319309628 | Polarimetric HPLC detector was used to acquire chromatograms for lavender lavandin essentials oils on different chiral stationary phases . Amylose tris immobilized on silica allowed the best separation of the numerous chiral phytomarkers and was thus used to obtain a chiroptical fingerprint for 158 samples of French lavender lavandin EOs . Samples from different varieties were collected over three crop years from four different locations in France to take into account seasonal and geographic origin variations . The combination of the polarimetric fingerprints and chemometrics was tested for varietal discrimination . We assessed the ability to discriminate the EOs samples and their variety by partial least squares discriminant analysis . This case study showed that liquid chromatography with polarimetric detector in tandem with chemometric analysis was efficient to differentiate the varietal origins of French lavender lavandin EOs . | Differentiation of varietal origins of French lavender lavandin essential oils. Characterization of essential oils using chemometrics and chiroptical fingerprints. Polarimetric detector was used to obtain chiroptical fingerprints. Characterization of essential oils by their chiral markers. Chiral chromatography with polarimetric detector in tandem with chemometrics analysis. |
S002196731930963X | The conversion of lignocellulosic biomass is a major challenge in the field of renewable energies and bio based chemicals . The diversity of biomasses and processes leads to complex products having a wide range of polarities and molecular weights . Nowadays the molecular description of these oxygenated matrices is still largely incomplete and new analytical strategies are required to have a better understanding of biomass products properties . The present study proposes a reliable protocol based on successive liquidliquid extractions prior to high performance liquid chromatography hyphenated to high resolution tandem mass spectrometry HPLC MS | Characterization of an industrial lignocellulosic biomass sample. Selective and controlled multi step liquidliquid fractionation. High resolution mass spectrometry hyphenated to liquid chromatography. Structural elucidations with multi stage fragmentation experiments. |
S0021967319309641 | A major strength of capillary electrophoresis is its ability to inject small sample volumes . However there is a great mismatch between injection volume and sample volumes . Electromigration based sample preparation methods are based on similar principles as CE . The combination of these methods with capillary electrophoresis could tackle obstacles in the analysis of dilute samples . | Three phase electroextraction was coupled directly to capillary electrophoresis. A new method for sensitive analysis of biogenic amines was developed. Application of the method to urine shows promise for use in metabolomics. |
S0021967319309653 | A chromatographic system was adapted to allow monitoring of eluent of preparative column via absorbance and with the chromatographic analysis of the target macromolecule on the same chromatographic system . The proposed approach was tested on important macromolecules such as monoclonal antibodies monoclonal antibody aggregates and plasmid DNA . A frontal analysis was made on the preparative column while a chromatographic on line analysis was performed by sequentially injecting the preparative column outlet on a convection based analytical column operating on the same chromatographic system . Cation and or anion exchangers were used as the chromatographic media depending on the sample to be purified . The method was found to be robust and reproducible . To adjust the limit of detection an algorithm varying the number of injections was used enabling accurate monitoring of an early breakthrough for concentrations below 1 of the feed concentration . The accuracy varies according to the applied flow rate but it is typically in the range of few percent or even below . Due to its simplicity and flexibility the proposed method can be easily adapted to a pharmaceutical environment . | Monitoring the effluent of the preparative column by rapid chromatography on a single chromatographic system. Fast chromatographic analysis was allowed at low pressure using convection based chromatographic columns. Limit of detection can be tuned by sample loop and variable number of injections. Typical method accuracy is in the range of few percent or below. |
S0021967319309665 | Recently it has been reported that immobilized chlorinated type chiral stationary phases based on cellulose tris are able to express an outstanding enantioselectivity towards the structure of 2 benzamide . We now introduce two homologue series of chiral sulfoxides based on the same 2 benzoyl core as the prototype of new selectands for HPLC whose enantioselectivity could be modulable through the replacement of the benzyl group with an unbranched alkyl chain varying in length from 1 to 5 carbon atoms . HPLC parameters such as mobile phase composition and column temperature have been carefully evaluated in order to get pertinent structure enantioselectivity relationships . The enantiomer elution order was unambiguously determined by a combined strategy involving theoretical and experimental procedures . Two cases of temperature dependent inversion of the elution order of enantiomers in the operative temperature range of chiral chromatographic support were observed . | This paper describes the HPLC behavior of two sets of chiral sufoxides on the IC 3 and IC CSP. The analytes contain different alkyl groups Me Et n Pr n Bu and n Pe . The role of the alkyl groups on retention and enantioselectivity was demonstrated. The thermodynamic aspects of enantioseparations were investigated. The retention and enantioseparation processes were analyzed in terms of enthalpic entropic control. |
S0021967319309677 | A direct procedure based on thermal desorption gas chromatography tandem mass spectrometry was developed for the fast extraction of seven polychlorinated biphenyls from sediments and soils . PCBs were directly extracted from 20 to 75mg of sample without any chemical pre treatment or use of organic solvents after the addition of 10L internal standard in acetone . Sample treatment was totally automated . PCBs were extracted at 250 | TDGCMSMS has been proposed for the automated and direct extraction of PCBs from soil and sediment. Extraction time and solvent consumption is assumed to be close to zero. A certified reference material was analysed with comparable results. Field sample results were comparable with those obtained by a reference extraction procedure. Greenmetric evaluation of the proposed and conventional methods has been carried out. |
S0021967319309690 | Improvements in sample preparation separation and mass spectrometry continue to expand the coverage in LC MS based lipidomics . While longer columns packed with smaller particles in theory give higher separation performance compared to shorter columns the implementation of this technology above commercial limits has been sparse due to difficulties in packing long columns and successfully operating instruments at ultrahigh pressures . In this work a liquid chromatograph that operates up to 35kpsi was investigated for the separation and identification of lipid species from human plasma . Capillary columns between 1550cm long were packed with 1.7m BEH C18 particles and evaluated for their ability to separate lipid isomers and complex lipid extracts from human plasma . Putative lipid class identifications were assigned using accurate mass and relative retention time data of the eluting peaks . Our findings indicate that longer columns packed and operated at 35kpsi outperform shorter columns packed and run at lower pressures in terms of peak capacity and numbers of features identified . Packing columns with relatively high concentration slurries while sonicating the column resulted in 634 increase in peak capacity for 50cm columns compared to lower slurry concentrations and no sonication . For a given analysis time 50cm long columns operated at 35kpsi provided a 2095 increase in chromatographic peak capacity compared with 15cm columns operated at 15kpsi . Analysis times up to 4h were evaluated generating peak capacities up to 4105 | 1550cm columns operated up to 35kpsi for lipid separations. Chromatographic peak capacities over 400 for lipid extract from human plasma. Putative lipid identification of nearly 500 lipids from human plasma extract. Resolution of regional and geometrical lipid isomers. |
S0021967319309707 | Countercurrent chromatography is a unique support free liquid liquid partition chromatography . Since it was invented by Y. Ito in 1960s CCC has been widely accepted and applied as popular separation and purification technique for natural and synthetic complex . However up to date there is little study to address on hydrophobic and hydrophilic interactions in CCC process although hydrophobic interaction chromatography and hydrophilic interaction chromatography as solid support chromatographic techniques are widely applied at different stages of downstream processing . In fact hydrophobic and hydrophilic interactions might be more popular in CCC separation than that in the liquid chromatography . For example adding small solvents or additives in two phase solvent systems may change significantly hydrophobic or hydrophilic interactions between solvents and solutes . Normally CCC separation employs a light and hydrophobic organic phase as the stationary phase and a heavy and hydrophilic aqueous phase as the mobile phase . Hydrophobic interactions between the solvent system and solutes will increase the partition coefficients | Hydrophobic and hydrophilic interactions in CCC have been first highlighted. Hydrophobic interaction in CCC leads to larger. values and longer retention time. Hydrophilic interaction in CCC results in smaller. values and shorter retention time. Some solvents or additives may enhance hydrophobic or hydrophilic interactions. Hydrophobic and hydrophilic interactions are useful for. targeted CCC separation. |
S0021967319309719 | Ultraviolet radiation from sunlight causes DNA damage in skin cells by formation of photoproducts mainly cyclobutane pyrimidine dimers which are reverted by exogenous CPD photolyase preventing photoaging and skin cancer . High performance liquid chromatography tandem mass spectrometry method for quantification of CPD photolyase activity was developed to search new enzymes sources for dermatology or clinical studies . The method was based in the enzymatic conversion of a 15mer oligonucleotide containing a center cyclobutane thymidine dimer to the restored 15mer oligonucleotide . Three ion pair reagent were evaluated by response surface methodology to increase mass intensities . Additionally chromatographic separation of oligonucleotides was performed . The selected mobile phase was 15mM diisopropylethylamine 20mM hexafluoroisopropanol in methanol . The method allowed total separation between the oligonucleotides studied by using the core shell technology which reduce the diffusion time of the analyte into the column increasing the efficiency and minimizing the analysis time at 7min . The mass spectrometry detection allowed a high selectivity and sensitivity . This is the first time where MRM modality has been employed with this specific purpose . Oligonucleotides recovery from reaction mixture was 94 and the limit of quantification was 13.4nM for 15mer . The method was evaluated with a recombinant CPD photolyase from | Method development for CPD photolyase activity quantification by UHPLCMS. Ion pair reagent allowed separation of CPD and 15mer oligonucleotide in C18 column. Sensitive and selective method with reduced analysis time. CPD photolyase activity in purified and crude extract was performed. |
S0021967319309732 | The application of chiral ionic liquids in capillary electrophoresis for enantioseparation has received considerable attention in the past few years however the use of chiral ILs as ligands in ligand exchange capillary electrophoresis has been reported only in a few papers . In this work several tetraalkylammonium amino acid ILs including tetramethylammonium | Three TAA AAILs were first applied in LE CE to act as chiral ligands. TMA. Arg showed significant superiority compared with most reported AAIL ligands. Most analytes were enantioseparated with satisfactory Rs in short migration times. Factors influencing the novel LE CE method were systematically investigated. |
S0021967319309744 | The feasibility of measuring the aging and degradation of PBX 9501 via online two dimensional liquid chromatography is investigated and a preliminary instrumental setup and method is developed . Plastic Bonded eXplosive 9501 is nominally composed of 94.9wt HMX 2.5wt Estane 5703 2.5wt BDNPA F 0.1wt Irganox 1010 and PBNA | Viability of 2D LC for analyses of aged plastic bonded explosives PBX is explored. 2D LC method with RPLC in. D and SEC in. D using a comprehensive setup LCLC . A simple sample preparation is proposed. Various SEC and HPLC experimental parameters are explored for analysis of PBX 9501. Demonstrated potential of LCLC on a library standard and aged sample of PBX 9501. |
S0021967319309768 | Retention rules are well known in liquid chromatography . For the mobile phase composition retention decreases when adding organic solvent to water for reversed phase or increasing water proportion for hydrophilic interaction liquid chromatography and a decrease in temperature usually increases retention . For supercritical fluids the fluid density which is related to temperature and column back pressure is significant for neat CO | Effects of backpressure and temperature changes in SFC with varied modifier percentages. Expected and surprising retention behaviors on polar nonpolar and aromatic phases in SFC. Subtle effects of particle modifications or isopropanol used on retention behaviors. |
S002196731930977X | Isomers derived from natural products are promising candidates for drug discovery . However characterization of isomers by mass spectrometry especially stereoisomers and positional isomers remains a large challenge due to insufficient reference standards and isomers highly similar fragmentation pathways or nondistinctive ion abundances . Herein this report presents the first proposal of a method combining multiple diagnostic ion neutral loss postanalysis and especially untargeted fingerprint analysis of all fragment ions by means of a home made program and chemometrics to profile chemical components and recognize their isomers derived from medicinal plants . As a proof of concept the chemical profiling of phenylethanoid glycosides and their isomers which showed remarkable neuroprotective anti inflammatory and immunomodulatory effects was performed . Using DINL to extract PhGs and FAAFI to distinguish their stereoisomers and positional isomers as many as 87 PhGs including 14 isomers were tentatively identified from | A new strategy was developed to screen metabolites and discriminate isomers. Phenylethanoid glycosides and their isomers from. were elucidated. Fingerprint analysis coupled chemometrics was used for isomers discrimination. 101 compounds including 14 isomers were identified or putatively characterized. |
S0021967319309781 | A headspace solid phase microextraction Arrow method coupled with gas chromatography mass spectrometry was developed for the quantitation of a large number of aroma compounds in Chinese liquor . Optimization of extraction conditions by a central composite experimental design revealed that the dilution of the alcohol content of 5mL of Baijiu to 10 followed by the addition of 1.5g of NaCl and subsequent SPME Arrow extraction with DVB CAR PDMS fiber coating over 45min at 45C was the most suitable . The quantitative method allowed the extraction and identification of 82 aroma compounds in the Baijiu sample . The method was validated with good repeatability inter and intra day precision and accuracy . Furthermore the method was validated successfully for the most significant compounds and was applied to study the composition of volatile compounds in different types of Baijiu . This research proved that SPME Arrow is an effective method for the extraction of aroma compounds in Baijiu and other distilled spirits . This developed method will allow improved analysis of other distilled spirits . | HS SPME Arrow sampling developed for volatile aroma compound extraction in Baijiu. HS SPME Arrow fiber affords improved extraction efficiency than that of SPME fiber. Multivariate methods including RSM were used to optimize the HS SPME Arrow method. A method for quantitation of the 82 volatile compounds in Baijiu was established. |
S002196731930980X | It has been known that anion exchangers prepared by grafting poly onto Sepharose FF at ionic capacities over 600mmol L show both high protein adsorption capacity and uptake kinetics and charge reversal of PEI Sepharose by modification with succinic anhydride can produce protein cation exchangers of high capacity and uptake rate . Previously a | PEI Sepharose was modified via two different routes to derive cation exchangers. They are. and. routes. The. route showed a complex reaction mechanism. resins showed superior properties over the others. |
S0021967319310039 | We discuss several possible phenomena in electrophoretic systems with complexing agents present in the background electrolyte . In our previous work we extended the linear theory of electromigration with the first order nonlinear term which originally applied to acid base equilibria only by generalizing it to any fast chemical equilibria . This extension provides us with a fresh insight into the well established technique of elecktrokinetic chromatography . We combine mathematical analysis of the generalized model with its solution by means of the new version of our software PeakMaster 6 and experimental data . We re examine the fundamental equations by Wren and Rowe and Tiselius in the frame of the generalized linear theory of electromigration . Besides we show that selector concentration can increase inside the interacting analyte zone due to its complexation with the analyte which contradicts the generally accepted idea of a consumption of a portion of the selector inside the zone . Next we focus our discussion on interacting buffers . We demonstrate how such side interaction of the selector with another buffer constituent can influence measuring analyte selector interactions . Finally we describe occurrence and mobilities of system peaks in these EKC systems . | Linear theory of electromigration explained for EKC for the first time. New software PeakMaster 6 validated on experimental data in EKC. The well known Tiselius and Wren and Rowe s equations re examined. Changes in selector concentration inside the analyte zone inspected. Dependence of system peaks mobility on selector concentration investigated. |
S0021967319310040 | Lecithins are phospholipidic mixtures that can be part of microemulsions and liposomes . In this work ready to use preparations of lecithin have been tested as pseudostationary and mobile phases in EKC and LC respectively . The selectivity of two EKC systems one based on lecithin microemulsions and another on liposomes and of a LC system based on lecithin microemulsions has been evaluated through the solvation parameter model . In all cases solute volume and hydrogen bond basicity are the main descriptors that drive the partition process . While solute volume favors the retention of solutes hydrogen bond basicity has the contrary effect . In lecithin based EKC systems the hydrogen bond acidity of the solute leads to a higher retention while in the lecithin based LC system a minor retention is produced . The three lecithin systems have been compared through the solvation parameter model to other chromatographic systems most of them containing phospholipids . Principal component analysis reveals that lecithin systems cluster together with the other EKC systems based on phospholipids with an immobilized artificial membrane LC system with the octanol water reference partition system and with a SDS based microemulsion . Thus they all show similar selectivity . However the great advantage of using the ready to use lecithin systems is that the laborious liposome preparation is avoided and that their commercial availability makes them more affordable than IAM LC columns . Finally taking into account that lecithin has a high semblance to the mammalian cell membranes composition the ability of the three lecithin systems to mimic the pass of the solutes through the membranes has been evaluated . Experimental determinations have demonstrated that the skin partition of neutral solutes can be easily emulated especially using the lecithin microemulsion EKC method . The model is robust and shows good prediction ability . | Volume and H bond basicity of solutes drive partition in lecithin chromatography. Solutes partition in LC and EKC systems containing phospholipids is similar. Lecithin based chromatography emulates skin partition in a fast cheap and easy way. |
S0021967319310052 | The incorporation of ion mobility into LCMS analysis has been demonstrated to result in the generation of superior quality MS and MS MS spectral data as well as providing enhanced resolution in the IM dimension based on lipid class . Here a sub 4 min microbore LC ion mobility accurate mass MS method has been developed for the rapid profiling of lipids in biological fluids . The method was scaled directly from a conventional 12 min LC MS analysis maintaining the chromatographic performance and lipid separation observed in the longer methodology giving a 75 saving in mobile phase consumption and analysis time . Because of the additional dimension of separation provided by IM improvements in mass spectral quality from the increased resolution of co eluting species were also seen when compared to the same separation without IM thus aiding the identification of target lipids . When applied to human plasma samples some 5037 and 2020 mass retention time features were detected following adduct deconvolution and of these 3727 and 800 of those present in the pooled plasma QC samples had a CV of below 30 for positive and negative ESI modes respectively . The method was applied to the analysis of a pilot set of commercially sourced breast cancer plasma samples enabling the differentiation of samples from healthy controls and patients based on their lipid phenotypes . Analysis of the resulting data showed that phosphatidylcholines triglycerides and diglycerides exhibited lower expression and phosphatidylserine showed increased expression in the breast cancer samples compared to those of healthy subjects . The coefficients of variation determined by reference to the QC data for all of the features identified as potential markers of disease were 6 or less . | A rapid microbore UHPLCIMMS method for profiling lipids is described. This provides lipid class separation a 75 reduction in solvent usage and run time. Plasma extracts showed differences between controls and breast cancer patients. Reduced PC TAG and DAG concentrations and higher PS expression in study samples. Coefficients of variation of potential disease markers were 6 or less. |
S0021967319310064 | In the nutrition field there is a lack of understanding about the impact that dietary chiral composition may have on health especially regarding cooked meals . Chiral amino acids are naturally present in food and their proportion may vary quite a lot . Besides the | Optimization of an LCMS MS method for absolute quantitation of 17. AAs in food. Validation of the method with cooked meals and LLOQ are 2.0ng mL for most of them. Application of the method to healthy breakfast lunch and dinner meal samples. Absolute levels of D AAs are given per daily food intake and within each main meal. Method applicable to quality control purposes in food. |
S0021967319310088 | Four polar stationary phases have been characterized in supercritical fluid chromatography by linear free energy relationships method with an extended set of Abraham s descriptors . Temperature 2555 | Four polar stationary phases have been characterized in SFC by LFER method. Temperature and pressure effects on retention of 89 test compounds were studied. Temperature and pressure variations lead to small but traceable changes in LFER coefficients. The direction and scale of temperature effects depend on stationary phase type. Temperature and pressure have moderate effects on selectivity. |
S002196731931009X | X ray computed tomography has been demonstrated to be capable of imaging 1mL chromatography packed beds under compression visualising the 3D structure and measuring changes to geometry of the packing . 1mL pre packed columns did not exhibit any structural changes at vendor specified flow rate limits however cellulose beds did compress at higher flow rates that were imaged before during and after flow . This was used to visualise and quantitate changes to porosity tortuosity and permeability based on simulation of flow through the packed bed structure using the imaging data . When using a high flow rate it was found that a decrease in porosity could be measured during compression before reverting after flow had ceased with corresponding changes to tortuosity and permeability also occurring . | 1mL pre packed beds imaged under compression using X ray CT. Digital erosion dilation approached compares porosity tortuosity relationship. Cellulose and ceramic materials investigated at both scales. Porosity tortuosity permeability and diffusivity quantified using 3D structure. |
S0021967319310106 | A high performance thin layer chromatography method was developed for rapid and easy to perform discrimination between five goldenrod species present in Europe the native | New HPTLC based approach for distinction of goldenrod. species. First cholinesterase diabetes and bacterial inhibitory potential of compounds. Labdane diterpenes and polyacetylenes as multipotent bioactive compounds. HPTLC EDA combined with DART HRMS and HPTLC ESI HRMS MS. Preparative scale bioassay guided isolation of multipotent compounds. |
S0021967319310118 | Molecularly imprinted polymers with tailor made recognition sites are used in water analysis for selective sample pretreatment before quantitation . The exceptional performance of MIPs with reduced interferences and matrix effects during sample preparation has resulted in selective and precise analytical methods by enhancing chromatographic separation and detection . MIPs are fabricated using a varying range of synthetic procedures and used as the adsorptive phase in solid phase extraction dispersive solid phase extraction solid phase microextraction stir bar sorptive extraction and membrane based extraction techniques . In this paper a comprehensive review of MIP technologies reported in the literature for water analysis is provided . MIPs are critically evaluated using key performance criteria such as adsorption capacity imprinting factor chromatographic retention factor and cross selectivity . The recent advances of MIP technologies including the preparation protocols applications and developments are discussed . Additionally the performance of MIPs which can be improved by optimizing the composition of the polymeric network is reviewed regarding the characteristics of rebinding medium . The limitations of MIPs for water analysis especially restricted selectivity for water soluble analytes material wettability and MIP inhomogeneity are discussed by providing the possible solutions . Finally some novel applications and prospects for online rapid and direct analysis of environmental samples using MIPs are included . | MIP sorbents have been widely used for selective extraction in sample preparation. A critical evaluation of MIPs in the analysis of environmental waters is provided. Selectivity and efficiency of MIPs are evaluated regarding rebinding medium. The limitations of MIPs for water analysis are assessed. Direct and online analysis of organic pollutants using MIPs is described. |
S002196731931012X | From the analytical chemistry point of view an ideal sample preparation method should be simple rapid automatic selective precise exhaustive reproducible and protect the analyte of interest from degradation . In this study a novel sample preparation method named pressurized matrix solid phase dispersion | A novel and advanced sample preparation methodology. MSPD was proposed. The. MSPD was performed with LC MS instrument. The. MSPD can simultaneously extract separate purify isolate and analyze endogenous components. The. MSPD allowed for isolation of some pure compounds with MS guided fractionation. Subsequent NMR analysis permitted further structural elucidation of compounds. |
S0021967319310131 | The petroleum industry is increasingly concerned with the conversion of vacuum residues as a consequence of decreased conventional crude oil availability . The compositional analysis of heavy oil products has become a key step in conversion processes but the complexity of these oil matrices tends to increase with their boiling point . In this study comprehensive two dimensional liquid chromatography coupled to inductively coupled mass spectrometry is considered with a view to meet new requirements and to bring additional information regarding the species present in these matrices . In search for a high degree of orthogonality two separation techniques involving two different retention mechanisms were evaluated Size Exclusion Chromatography and Reverse Phase Liquid Chromatography . In SEC the analytes are separated according to their molecular weight while according to their hydrophobicity in RPLC . The separation power of both individual separation techniques was first evaluated . Off line and on line LCxLC were compared on the basis of an optimization approach . It is shown that off line SECxRPLC can provide for the same analysis time of 150min a higher peak capacity than on line RPLCxSEC while a similar dilution factor but also requires far fewer fractions to be analyzed . Asphaltenes which constitute the heaviest fraction of crude oils were analyzed by the developed off line SECxRPLC method . The resulting 2D contour plots show that co elutions could be removed leading for the first time to new information on high molecular weight species containing sulfur and vanadium . | SECxRPLC was successfully applied to complex petroleum samples. Detection by ICP MS MS allowed to simultaneously analyze S Ni and V. Information on both MW and hydrophobicity was obtained within a single run. An effective peak capacity of 2600 was achieved in 150min in off line SECxRPLC. On line RPLCxSEC was evaluated by a pareto optimality approach. |
S0021967319310143 | A rapid synergistic cloud point extraction for nine alkylphenols coupled with high performance liquid chromatography and fluorescence detection was developed . The non ionic surfactant polyethylene glycol 6000 was selected as the extractant . Acetonitrile was used as a revulsant and synergistic reagent with Na | A rapid synergistic cloud point extraction was first developed for alkylphenols. Acetonitrile worked as a new revulsant and synergic reagent in this study. The CPT of PEG 6000 was decreased to ambient temperature by acetonitrile and sodium sulfate. BoxBehnken design with the desirability function was used to optimize the RS CPE condition. All of the extraction efficiencies obtained were higher than 91.4 . |
S0021967319310155 | Gas chromatography and vacuum ultraviolet spectroscopy are powerful and complementary techniques for the analysis of small molecules in forensics . Most notably flame ionization detection is commonly used with GC to identify and quantify volatile compounds . An FID s price point and ease of use makes it an attractive approach for routine laboratories that are in high demand for forensics analysis but with the contingency that an FID relies on retention time for identification and quantification . A new and innovative method using static headspace gas chromatography coupled with vacuum ultraviolet spectroscopy was developed for the quantitative determination of ethanol in blood and identification of inhalants . This study investigates the possibility of using VUV as an alternative technique to traditional methods that use FID and mass spectrometry in toxicology and forensic analysis . VUV brings both identification and quantitation based on Beer Lambert s Law while using a simple single column solution . This paper investigates 25 compounds including ethanol methanol acetone benzene and toluene using a 130240nm wavelength range for identification and quantification using GC VUV even when coelutions occur . Ethanol was examined under a concentration range of 9 to 495mg dl and the method was found to be linear with an r | Gas chromatography vacuum ultraviolet spectroscopy for blood alcohol inhalants. Vacuum ultraviolet spectroscopy provides authoritative identification of compounds. Spectral deconvolution allows for accurate quantitation of coeluting peaks. |
S0021967319310167 | Mechanistic modeling of protein adsorption has gained increasing importance in the development of ion exchange chromatography processes . The most common adsorption models use a stoichiometric representation of the adsorption process based on the law of mass action . Despite the importance of these models in model based development the stoichiometric representation of the adsorption process is not accurate for the description of long range electrostatic interactions in IEX chromatography limiting the application and mechanistic extension of these models . | A non stoichiometric adsorption model for IEC chromatography is derived. Adsorption is governed by electrostatic interactions inside an interaction force boundary layer. The model accounts explicitly for ionic strength and pH based on the protein primary structure. Model parameters are theoretically valid on different stationary phases. Effect of post translational modifications on protein adsorption can be simulated. |
S0021967319310180 | In this work the use of design of experiments and posterior data modelling by artificial neural network and least squares is presented as a suitable analytical tool for the performance optimization of a tandem mass spectrometric detector coupled to ultra high performance liquid chromatography for the analysis of seventeen veterinary drugs . Firstly a central composite design was built considering as factors the cone capillary extractor and radio frequency voltages of the mass spectrometer in order to obtain a proper combination to improve the sensitivity of the method . Secondly a one factor design considering the collision voltage was built to define the adequate voltage for each daughter ion . The response surface methodology was then applied and the prediction capability of ANN and LS were compared . As conclusion the ANN modelling provided better results than LS both in terms of the ANOVA and predicted areas results . The accuracy of the model prediction was between 85 and 125 confirming that the estimates of the model were correct and endorsing the optimization procedure as a suitable way to gather excellent results . The suitability of the new approach and its implications on the simultaneous analysis of seventeen veterinary drugs by ultra high liquid chromatography coupled to tandem mass spectrometry detection are discussed . | Efficient optimization of MS MS parameters by means of design of experiment. Performance evaluation of data modeling by least squares and neural network. Accurate model prediction of seventeen veterinary drugs with results ranging from 85 to 125 . Advantages of 54 reduction in laboratory time and 80 in analyte waste. |
S0021967319310192 | This study presents the development of an efficient extraction protocol for amoxicillin from plasma with improved solubility and stability using pH control . Solubility and stability of amoxicillin in commonly used extraction solvents were determined using a newly developed stability indicating high performance liquid chromatography method . Following this protein precipitation mediated sample purification protocol was developed and validated along with the HPLC method for the extracted amoxicillin from rabbit plasma . The protocol was applied in a pharmacokinetic study in rabbits . A five fold increase in solubility and two fold increase in stability of amoxicillin was found by addition of acetate buffer in acetonitrile . PP mediated extraction protocol containing acetate buffer acetonitrile resulted in an extraction recovery of 80 for all the samples . The HPLC assay following extraction was found linear | Solubility and stability of amoxicillin was improved by the addition of a buffer. The extraction of amoxicillin from plasma was enabled via pH control. A stability indicating HPLC assay enabled the analysis of amoxicillin in plasma. Pharmacokinetic analysis validated the extraction protocol. |
S0021967319310209 | This paper proposed an accurate and sensitive analytical method based on the combination of Liquid Chromatography Quadrupole Time of Flight Tandem Mass Spectrometry system with Quadruple Isotope Dilution Mass Spectrometry ID | An accurate and precise method was developed for determination of diuron. The LOD and LOQ values were found to be 14.6 and 46.5gkg. respectively. ID. MS strategy was implemented after the synthesis of diuron d6. Developed method was applied to seaweed samples with satisfactory percent recoveries. |
S0021967319310222 | Nintedanib is a tyrosine kinase inhibitor recently approved for the treatment of idiopathic pulmonary fibrosis . As a new drug no monograph is available so far in official compendia . A liquid chromatography tandem mass spectrometry method is presented for the simultaneous determination of NIN and its seven potential impurities . The risk based approach of Analytical Quality by Design was applied in method development . The critical method parameters were the type of organic solvent in the mobile phase formic acid percentage column flow rate oven temperature gradient slope of organic eluent . The critical method attributes were selected as analysis time and selectivity between the main compound NIN and the adjacent peaks . Design of Experiments methodology was effectively employed for establishing the relationship between the CMPs and the CMAs . In the scouting step a Restek Ultra AQ C18 core shell column was selected and then the effects of different levels of the five CMPs on the CMAs were evaluated by means of a 3 | A LC MS MS method for the assay of nintedanib and its impurities was developed. Method development was carried out by Analytical Quality by Design approach. A 35 16 symmetric matrix was used in the screening phase. Box Behnken Design allowed the contour plots to be obtained. Method operable design region was defined by drawing probability map. |
S0021967319310246 | As an endogenous nucleoside adenosine was significant for the diagnosis and treatment of some diseases such as schizophrenia . However due to the complicated matrix interference it was difficult to monitor trace or ultra trace adenosine directly in bio samples . In this contribution a novel in tube SPME technique based on aptamer Au nanoparticles coated open tubular fused silica capillary was established to separate and enrich adenosine in bio samples with high affinity . Therefore a uniform and dense AuNPs layer was coated on the inner surface of the open tubular capillary and then adenosine aptamer was immobilized on AuNPs with a high capacity of 2.44g per 27 cm capillary . As a result the capillary shown high selectivity to adenosine with a selectivity factor of 14.4 when compared with the scrambled aptamer AuNPs coated capillary . Also the extraction amount of adenosine was 2.824.8 times higher than those of its structural analogs and contrast such as guanosine uridine cytidine thymidine and toluic acid . After the optimization of extraction conditions the aptamer AuNPs coated in tube SPME HPLC method was developed for the adenosine assay with the linear range of 0.0020.100gmL | An aptamer AuNPs coated in tube solid phase microextraction capillary was prepared. 2.84gcm. of the bonding amount of Au coated on the inner surface was obtained. 2.44g of aptamer immobilization capacity was obtained in a 27 cm capillary. Aptamer AuNPs coated capillary showed improved selectivities to adenosine. Adenosine was monitored with aptamer AuNPs coated capillary SPME HPLC UV method. |
S0021967319310258 | In this study a monolithic enzyme reactor based on a strategy of green synthesis was successfully prepared in a capillary with trypsin immobilized by thiol ene click reaction . A polymer of poly butyl methacrylate | IMER based on deep eutectic solvent was prepared by thiol ene click reaction. Michaelis constants and maximum reaction rate were 2.1mM and 0.028mol min. A rapid digestion of BSA on the IMER was 864 times faster than in solution digestion. 1034 protein groups can be identified from protein extracts of rat liver by the IMER. |
S002196731931026X | Iron free HPLC systems better known as biocompatible systems are generally regarded to be chemically more inert compared to conventional HPLC systems . In this work we studied the chromatographic behavior of some classes of compounds of pharmaceutical interest analyzed with iron free systems . Issues typically associated with metal contamination i.e . strong peak tailing were observed when using an amide polar embedded column . Effects of the contamination were visible when anhydrous methanol acetonitrile was used indicating that this solvent albeit generally considered safe for conventional HPLC systems induce corrosion of iron free systems . The confirmation of titanium as main acting contaminant came from systematically studying the contribution of each wetted component of the HPLC system on peak shape of affected molecules . Quantification of titanium by ICP MS analysis of effluents provided further evidence on the source of contamination . A mechanistic description of the complex interaction between titanium ions organic molecules and column stationary phase is proposed . In the perspective of developing methods that are fully portable between stainless steel and titanium systems recommendations are given in terms of potentially sensitive molecules suitable mobile phase conditions and type of column to be used . | Methanol acetonitrile solvent causes titanium corrosion. Titanium leaching from biocompatible HPLC can cause peak tailing. Peak tailing can be caused by the formation of complexes with immobilized titanium. |
S0021967319310295 | An accurate quantification of phenolic compounds present in several kind of craft beers corresponding worts ingredients and spent products was performed by LCMS MS in this study . The dilution 1 2 of the sample with the mobile phase gave the best results offering a very fast and simple method to reduce the matrix effect . A validated method was applied to six different types of craft beers their worts starting and spent products such as barley malts and barley husks starting hops and spent hops and finally starting yeast and spent yeasts to quantify the selected phenolic compounds . The Total Phenol Content of barley malts is not negligible and it results almost prevalently due to trans | An accurate quantitative analysis of craft beers by LCMS MS identified phenolic acids and flavonoids mostly coming from malt and bitter acids and prenylflavonoids coming from hop. Dilution 1 2 of the sample with the mobile phase offered a very fast and simple method to minimize the matrix effect. Most polyphenols are absorbed into the yeast added for the fermentation. Spent yeast can be considered a source of polyphenols coming from beers ingredients. |
S0021967319310301 | Wastewater based epidemiology is a growing research field which provides valuable information on community drug use and chemical exposure . One parameter critical to estimations of drug use is the catchment area population . A population biomarker could be used to provide this information . This study evaluated the analytical suitability of three endogenous biomarkers of human activity the serotonin metabolite 5 hydroxyindoleacetic acid which has previously been proposed and two further candidates the catecholamine metabolites vanillylmandelic acid and homovanillic acid . An analytical method involving derivatization was developed and validated for two candidates 5 HIAA and HVA by liquid chromatography mass spectrometry . The best performance was obtained for VMA as the underivatized analyte . The derivatized extracts produced a 100 times better sensitivity . The three neurotransmitter metabolites were evaluated as population biomarkers in wastewater samples . All were stable in sample not lost upon filtration and showed stable inter day mass loads over seven days for a metropolitan wastewater treatment plant . When applied to a small community during a festival period mass loads of both HVA and VMA reflected the increase in the catchment population whilst 5 HIAA proved to be more variable . | Development of a UHPLC MS MS method for neurotransmitter metabolites in wastewater. Derivatization substantially enhanced sensitivity for 5 HIAA and HVA. Low inter day mass load variability for 5 HIAA HVA and VMA was measured. HVA and VMA followed transient population changes in wastewater during a festival. |
S0021967319310313 | agonists which have been illegally used in animal production in some countries can induce bioaccumulation when blood is converted by rendering into blood meal . Unfortunately available data on this topic are scarce which result in lack of risk assessment . Therefore in this research a method for simultaneous determination of 22 agonists in blood meal by liquid chromatography coupled with tandem mass spectrometry using isotope dilution was developed . The recoveries of the developed method ranged from 68.6 to 118.8 with RSD at below 20 . the limit of detection is blew 1g kg . The change in agonist form added and incurred blood into blood meal and long stability of agonist in blood meal were studied . Then we analyzed blood meal for 22 agonists using this method . The results suggest blood meal is a possible pathway for agonist reentry into animals . Potential risks of agonist residues in blood meal were examined . This study is the first to explore source of agonist residues in blood meal change in processing produce and stability in stored stage . | A new method for analysis of 22 agonists in blood meal was developed. The method was successfully applied to analyze agonist in blood meal. agonist residues in process and stored blood meal have been studied firstly. |
S0021967319310325 | Jumonji domain containing proteins play an important role in the epigenetic regulation of gene expression . Aberrant regulation of histone modification has been observed in the progression of a variety of diseases such as neurological disorders and cancer . Therefore discovery of selective modulators of JMJDs is very attractive in new drug discovery . Herein a simple capillary electrophoresis method was developed for screening of inhibitors against JMJD3 . A known JMJD3 inhibitor GSK J1 5 carboxyfluorescein labeled substrate peptide with an amino acid sequence of KAPRKQLATKAARKSAPATGG as well as a small chemical library composed of 37 purified natural compounds and 30 natural extracts were used for method development and validation . The separation of substrate from its demethylated product was achieved by addition of polycation hexadimethrine bromide in the running buffer . The enzyme activity was thus assayed accurately through separating the demethylated product from the substrate and then measuring the peak area of the product . The enzyme inhibition can be read out by comparing the peak area of the demethylated product obtained in the present of inhibitors and that of the negative control in the absence of any inhibitor . The merit of the method is proved by discovering two new JMJD3 inhibitors salvianic acid A and puerarin 6 O xyloside . | We developed a CE method for screening of histone demethylase JMJD3 inhibitors. The method is straightforward and robustness. Coating the capillary with a positively charged polyelectrolyte is necessary for the method. Salvianic acid a and puerarin 6 O xyloside were identified as new JMJD3 inhibitors. |
S0021967319310349 | This work presents the investigation of utilizing adenine functionalized polypropylene glycol for capillary gas chromatographic separations . The statically coated APPG column showed moderate polarity and high column efficiencies of 4660plates m and 4376plates m determined by | Adenine functionalized polypropylene glycol. High resolution of the Grob test mixture and the isomers of anilines and phenols. Simultaneously improved column selectivity and inertness. Advantageous performance over conventional stationary phases. |
S0021967319310362 | The purpose of this work was to compare side by side the performance of packed bed and membrane chromatography adsorption processes for protein purification . The comparison was performed using anion exchange media with the same ligand immobilized on the adsorbing surface namely the strong Q quaternary ammonium group R CH | Direct comparison between membrane and packed bed column. Packed bed has higher binding capacity. The difference decreases significantly at increased superficial velocity. Membrane adsorber capacity is flow rate independent by a variety of measures. At low residence times the membrane adsorber outperforms the packed column. |
S0021967319310374 | Authentication of original species is embedded in the quality control system of herbal medicines . In this work ultra performance liquid chromatography quadrupole time of flight mass spectrometry based untargeted metabolomics coupled with chemometric analysis was utilized for the precise authentication of the | A stepwise analysis approach was proposed to enlarge differences among species. Species specific markers of eight. species were firstly discovered. species in 16 commercial pharmaceutical products were authenticated. |
S0021967319310611 | A microextraction technique termed promoted reaction microextraction based on a liquid liquid microextraction was developed by applying a chemical reaction for promoting the extraction of the analytes into the extracting solvent . PRME is a very simple rapid and high performance method for extraction and pre concentration of organic compounds from water samples . In PRME different types of chemical reactions can be used . In the present work an acid base reaction that produces a gaseous product is employed . In this method appropriate amounts of auxiliary solvent acidic promotor and extraction solvent were added rapidly into a water sample containing a basic promotor . After adding the solution containing the acidic promoter to the water sample containing the basic promoter the acid base reaction started with high intensity . The reaction product consisted of salt water and carbon dioxide gas . The produced carbon dioxide generated bubbles in the reaction medium that promoted the extraction of the analytes into the extracting solvent . After centrifuging the fine particles of the extraction solvent were sedimented in the bottom of the conical tube . The denes phase was analyzed by gas chromatography mass spectrometry . Several parameters affecting the extraction of 17 target pesticides by PRME GC MS were investigated . Under the optimum conditions the calibration graph was linear in the range of 0.03540.0gL | A simple rapid and high performance pre concentration is represented. The pretreatment involves a LLME in which a gas generation reaction occurs. The produced gas bubbles from acid base reaction promote the transfer of the analytes onto the extracting phase. The PRME allows the simultaneous quantification of pesticides from water samples. No devices or equipment was needed. |
S0021967319310623 | Sample preparation of complex matrices like food samples continues to be a challenge demanding great effort for improvements . In this study a new technique named balls in tube matrix solid phase dispersion is proposed based on a simplification of the conventional MSPD technique being all sample preparation performed directly in a closed extraction tube with the assistance of steel balls . An innovative method using BiT MSPD was successfully established for the determination of 133 pesticide residues in apple peach pear and plum by ultra high performance liquid chromatography with tandem mass spectrometry . Several sorbents were evaluated as solid support in different proportions with the sample . The homogenization step using mortar glass rod or steel balls with methanol and acetonitrile as extraction solvent was evaluated . Vortex and ultrasound assisted extractions were also tested . Best results were obtained with C18 homogenization with steel balls acetonitrile as solvent and ultrasound assisted extraction . Validation presented adequate trueness and precision results for the evaluated pesticides with recovery results ranging from 72 to 113 and RSD17 . Practical limit of detection and quantification for the compounds were 3 and 10gkg | A novel BiT MSPD technique was developed for first time for pesticides extraction from fruits. BiT MSPD is fast easy to perform and tools are cheap and very accessible. The use of balls improved the method efficience when compared to official methods. Practical method limit of quantification for 133 pesticide residues was 10gkg |
S0021967319310635 | Eicosapentaenoic acid and docosahexaenoic acid are essential omega 3 fatty acids in human nutrition . Dietary supplements containing these FA are available in the market and there is a need to assess their quality to prevent frauds . The purpose of this work was to optimize and validate a fast capillary electrophoresis method to determine EPA and DHA content in marine oils omega 3 supplements . Sample preparation comprised only a saponification step and analysis time was 8min . Validation was performed according to limits of detection and quantification linearity accuracy and repeatability . Ten real samples of marine oil supplements were analyzed by CE and compared to conventional gas chromatography method . No significant differences between both methods were found within 95 confidence interval . Overall CE method was successful to FA quantification and it could be used for fast FA monitoring during omega 3 supplement manufacture final product quality assurance and labelling . | A fast CE method was optimized and validated for omega 3 oil supplements. Analysis was completed in just 8min requiring only a prior saponification step. LOD LOQ linearity accuracy and repeatability tests were considered to validation. No significant differences were found between this approach and classic method. This fast simple and accurate method can be useful for routine quality control. |
S0021967319310647 | When assessing occurrence and exposure to toxic chemicals in drinking water developing methods that are sensitive and efficient is paramount . A new method was developed for the quantification of ten halobenzoquinones a class of disinfection by products in drinking water which have been shown to be more toxic than most regulated DBPs . This method uses a small sample volume with online solid phase extraction followed by liquid chromatography tandem mass spectrometry . Previous methods used offline SPE coupled with standard addition and a pre concentration step . This requires larger volumes of sample solvent and standards . The current method has comparable limits of quantification requires minimal sample preparation and analysis is almost entirely automated . It also includes 2 6 dibromo 3chloro 5 methyl 1 4 benzoquinone which was not included in previous methods . A stability test was conducted over a one week period with different preservatives including ascorbic acid sodium thiosulfate and formic acid . Method optimization included source temperature SPE size sample volume and SPE loading time . This method was validated using drinking water collected from four different drinking water plants spike recoveries of HBQs were between 70111 relative standard deviations of 20 and linearity of 0.98 . Further using this method we report the highest concentration of 2 6 dibromo 1 4 benzoquinone found in drinking water . | A novel method analyzing ten halobenzoquinones was developed. Automation resulted in increased efficiency for high throughput analysis. Quality control measures resulted in limits of quantification that are highly reproducible. Higher bromide to HOCl ratios increased formation of brominated halobenzoquinones. Highest concentration of 2 6 dibromo 1 4 benzoquinone reported in drinking water. |
S0021967319310659 | Chlorophyll pigments give the green colour to plants which is a quality attribute of food and vegetables . However the chemical structure of native chlorophyll can change during varied processes applied to plants which produce degradation compounds that could have a brown and unwanted colour . | Retention behaviour of chlorophyll and chlorophyll derivatives by SFC using varied modifiers. Improved separation of hydroxy pheophytins. and. and their epimeric forms. Method development of phytylated chlorophyll derivatives with the use of C18 stationary phase. Unusual conditions of backpressure for mobile phases containing carbon dioxide. |
S0021967319310660 | This paper presents a basic model of an automated system for predicting the detection limit and precision profile of measurements against concentration in chromatography . The fundamental assumption is that the major source of response errors at low sample concentrations is background noise and at high concentrations it is the volumes injected into an HPLC system by a sample injector . The noise is approximated by the mixed random processes of the first order autoregressive process AR and white noise . The research procedures are the description of the standard deviation of measurements in terms of the parameters of the mixed random processes the algorithm for the parameter estimation of the mixed processes from actual background noise the mathematical distinction between noise and signal in a chromatogram . When compounds are chromatographically separated each obtained signal is given the detection limit and precision profile on laboratory made software . A file of a chromatogram is the only requirement for the theoretical prediction of measurement uncertainty and therefore the repeated measurements of real samples can be dispensed with . The theoretically predicted RSDs are verified by comparing them with the statistical RSDs obtained by repeated measurements . Signal shapes on noise are illustrated at the detection limit and quantitation limit the signal to noise ratios of which are close to the widely adopted values 3 and 10 respectively . | A mathematical theory to describe the SD of measurement errors was developed. An automated system to validate a quantitative HPLC was proposed. The distinction between noise and signal was mathematically achieved by this system. The DL and precision profile were given to a signal by the laboratory made software. The laboratory made software can dispense with the repeated measurement in HPLC. |
S0021967319310684 | A novel combined vortex assisted dispersive liquid liquid microextraction micro solid phase extraction procedure for polycyclic aromatic hydrocarbons in ambient fine particulate matter of aerodynamic diameter of 2.5m PM | A combined microextraction procedure VA DLLME SPE was developed. PAHs associated with ambient air particulate matter PM. were determined. The PAH levels were determined using GC MS MS. The method showed good extraction efficiency. |
S0021967319310696 | Aldehydes originating from malt play an important role in beer flavour deterioration . In order to better understand the influence of malting process on beer staling it is necessary to acquire a reliable analytical methodology for determination of beer staling aldehydes in malt . Therefore the aim of this study was to evaluate extraction parameters which allow quantification of beer staling aldehydes present in pale malts . The method was validated with respect to linearity | Evaluating sample preparation for a fast quantification of aldehydes in pale malts. Malting technology influences the content of beer staling aldehydes in pale malts. Quantity of beer staling aldehydes introduced into the brewing could be controlled. |
S0021967319310714 | A high performance liquid chromatography method equipped with a boron doped diamond electrode was established for the simultaneous determination of phenol 4 ethylphenol guaiacol 4 ethylguaiacol 4 vinylguaiacol eugenol and | Efficient reversed phase separation and sensitive detection of 9 key flavoring phenolic compounds including guaiacol and phenol in whiskey using a core shell column with ECD at a BDD electrode. The BDD electrode with anti fouling properties and extended potential windows provided excellent detection sensitivity and selectivity. Popular Islay whiskey had significantly higher levels of flavorings compared to Irish Scotch and Highland whiskeys. The method can be extended to other polyphenols serving as markers to differentiate authentic whiskeys from their counterfeits. |
S0021967319310726 | The applicability of models to describe peptide retention in hydrophilic interaction liquid chromatography was investigated . A tryptic digest of bovine serum albumin was used as a test sample . Several different models were considered including adsorption mixed mode exponential quadratic and NeueKuss models . Gradient separations were performed on three different HILIC stationary phases under three different mobile phase conditions to obtain model parameters . Methods to track peaks for specific peptides across different chromatograms are shown to be essential . The optimal mobile phase additive for the separation of BSA digest on each of the three columns was selected by considering the retention window peak width and peak intensity with mass spectrometric detection . The performance of the models was investigated using the Akaike information criterion to measure the goodness of fit and evaluated using prediction errors . The | Five models were studied and compared for modelling retention of peptides in HILIC. Most suitable additives were established for three different types of HILIC columns. Models were compared using AIC values with the adsorption model performing best. The significance of model terms was studied using the F test for regression. Retention times for a BSA digest could be predicted within 2 . |
S0021967319310738 | Most of the reported covalent organic frameworks are hydrophobic limiting their adsorption application in sample pretreatment field . In this work sulphonate functionalized magnetic covalent organic frameworks composites were first synthesized by loading gold nanoparticles on Fe | Functionalized magnetic covalent organic framework composite was facilely prepared. Magnetic composites were employed for highly effective fluoroquinolones enrichment. MSPE HPLCMS MS method was developed for fluoroquinolones detection in food samples. |
S002196731931074X | Haloacetic acids are the second largest class of disinfection by products by weight in water and are more cytotoxic and genotoxic to mammalian cells than trihalomethanes the first largest class of DBPs . Gas chromatography is the most widely used technique for determining HAAs . Due to their polar nature derivatization prior to GC analysis is required . Typically derivatization is undertaken with acidic methanol which converts HAAs to the corresponding methyl ester and HAAs are quantified by measuring HAAMEs . In this study the interference from two other groups of DBPs the haloacetonitriles and haloacetamides on the determination of HAAs was investigated . HANs and HAMs at a range of concentrations were subjected to the same derivatization and analytical procedures as HAAs . The stability of HANs and HAMs under strongly acidic conditions was assessed and the operative mechanism of interference was investigated . The results showed that HAMs significantly interfered with the determination of the corresponding HAAs and the transformation rates of HAMs ranged from 6.5 to 45.7 while the impact of HANs can be neglected . The stability of HANs and HAMs under strongly acidic conditions indicated that hydrolysis was not the cause of the interference . Instead it was proposed that HAMs react with methyl alcohol to generate the same corresponding HAAMEs that was generated when HAAs reacted with methyl alcohol . A method for revising HAA concentrations in the presence of HAMs is suggested . | Presence of HAMs interfered with determination of HAAs using GC. Transformation rate of HAMs to corresponding HAAMEs ranged from 6.5 to 45.7 . Direct conversion of HAMs to corresponding HAAMEs caused the interference. A method for revising HAA concentrations in the presence of HAMs was proposed. |
S0021967319310751 | We introduce an integrated chip approach for a postcolumn segmentation of normal phase liquid chromatography . This is achieved by the seamless integration of a chiral NP chip HPLC column a flow focusing droplet generator and a segmented flow channel in a single microfluidic glass chip . This allows a continuous segmentation of the eluent into droplets which are picked up and transported via an immiscible continuous phase . The combination of NP chip HPLC and droplet microfluidics enables to fractionate and conserve chromatographic runs for further downstream processes at picoliter scale . An essential aspect is the proper choice of the continuous phase concerning polarity wetting properties and viscosity . For this purpose ethylene glycol is introduced which facilitates this first combination of normal phase chromatography and droplet microfluidics . By adjusting the flow rates and varying the generator geometry the size and frequency of the droplets could be precisely controlled . | Pioneering work joining normal phase chip HPLC and droplet microfluidics. Integration of a packed NP HPLC column and a droplet generator in glass chips. Ethylene glycol works as polar continuous phase. heptane eluent compartmentalized with moderate droplet frequencies. |
S0021967319310763 | Cyclodestrins are cyclic oligosaccharides well known for their ability to form host guest inclusion complexes with properly sized compounds . They have been used for decades as chiral selectors as well as drug delivery systems within the frameworks of separation science and pharmaceutical science . More recently their use has been extended to the field of extractive science under the stimulus of additional advantageous characteristics such as low price negligible environmental impact non toxicity as arising from the fact that natural CDs are starch degradation products . To abate their solubility in water and generate novel sorbents for solid phase extraction the following approaches have been employed | Classes of cyclodextrin based sorbents for solid phase extraction are illustrated. Advantages and shortcomings of each sorbent typology are discussed. Latest applications of these materials are presented. Future trends in preparing advanced cyclodextrin based sorbents are identified. |
S0021967319310775 | For a wide variety of hydrophilic interaction chromatography stationary phases a repeatable partial equilibration was demonstrated in gradient elution after purging with as little as 12 column volumes of mobile phase . Relative standard deviations of retention time of on average 0.15 could be obtained after 1 or 2 conditioning runs . The equilibration period must be kept strictly constant otherwise selectivity changes occur but this is not problematic on modern instruments . Partial equilibration was largely independent of stationary phase or gradient slope . Alternatively full column equilibration is favoured for stationary phases that do not trap extensive water layers and for materials with a wider pore size that have a lower surface area . Temperatures somewhat above ambient also shorten the equilibration time . Some stationary phases under optimum conditions can achieve full column equilibration using purging with 12 column volumes which is useful for rapid set up of isocratic separations or for conventional gradient analysis . | Repeatable partial gradient elution equilibrium shown for different HILIC columns. Rapid partial equilibration independent of stationary phase and gradient slope. Full equilibration time depends on water layer thickness on stationary phase. Full equilibration faster at elevated temperature and increased column pore size. Full equilibration achieved on some columns with passing only 12 column volumes. |
S0021967319310787 | Pesticide residue analysis in cannabis has become a subject of growing interest in North America since recent legalization in Canada and decriminalization for medicinal or recreational use in most US states . To meet regulatory and quality control standards cannabis products should be tested for both authorized and unauthorized pesticides . In Canada testing requirements mandated by Health Canada stipulate pesticide contaminant limits of quantification values of 0.023.0g g 0.012.5g g and 0.011.5g g for cannabis dried flowers oil and fresh plants respectively . Sample preparation and clean up methods reported in the literature for pesticide analysis in cannabis products include liquid liquid extraction solid phase extraction solid phase microextraction and QuEChERS whereas separation and detection methods include thin layer chromatography capillary electrophoresis high performance liquid chromatography and gas chromatography in combination with various detectors such as UV and mass spectrometers . Advantages and disadvantages of the various analytical methods used in pesticide analysis of cannabis products are evaluated in this review . Furthermore challenges ahead and future directions are discussed . | Overview of sample preparation methods. Pros and cons of each technique described. Overview of analytical methods for pesticide residue analysis in cannabis products. Challenges and future directions for pesticide residue analysis in cannabis products. |
S0021967319310805 | Fucoidans represent an intriguing class of fucose containing sulfated polysaccharides . The biological activities of these polysaccharides are related to their compositional and structural parameters whereby their degree of sulfation as well as molecular weight distribution and chain conformation play important roles . Modern NMR and mass spectrometry techniques allow elucidating details of the glycan structure but not the structure of the whole molecules in their native state . Accordingly the knowledge about the latter of the fucoidans is currently still limited . Contrary to traditional MW determination by SEC with column calibration SEC with triple detection provides not only the absolute | SEC with multiple detection is useful for structural characterization of fucoidans. Six fucoidans were heterogeneously and complex composed. Six fucoidans considerably differed in their molar mass and size characteristics. Typical fucoidans consisted of expanded flexible chains with branched structure. Molar mass and conformation of fucoidans influence their biological activities. |
S0021967319310829 | Pyrethrum extract is a natural insecticide that has been used worldwide for centuries with pyrethrins being considered active ingredients . Their purification is difficult due to their chemical structural similarity and instability to light . In the present study a coordination complex high speed counter current chromatography was used to separate pyrethrins from pyrethrum extract . The two phase solvent system composed of petroleum etherethyl acetate methanol water with 0.30mol L silver nitrate was selected for separation . As a result five pyrethrins including cinerin II pyrethrin II jasmalin II pyrethrin I and jasmalin I were obtained from 400mg crude extract in 6h by one step HSCCC separation with purities over 95 . The isolated compounds were identified by MS | Separation of pyrethrins by High speed counter current chromatography HSCCC for the first time. A coordination complexation method was used to separate pyrethrins. The presence of a silver ion complex agent significantly increased separation factor. |
S0021967319310830 | Untargeted steroid identification represents a great analytical challenge even when using sophisticated technology such as two dimensional gas chromatography coupled to high resolution mass spectrometry GCGC | Data driven approaches for GCxGC retention time predictions. 3D electrostatic potential and CNN were utilized to develop 3D QSRR models. CNN are able to learn geometric information which improves model prediction. Retention time prediction and HRMS information enable untargeted steroid annotation. |
S0021967319310854 | An on line high performance liquid chromatographydiode array detectorelectrospray ionizationion traptime of flightmass spectrometrytotal antioxidant capacity detection system was applied for the identification and evaluation of antioxidants in | An on line system was used to detect the antioxidant activity of. 80 compounds were separated and identified. DPPH and FRAP activities of active compounds were evaluated. 11 samples were analyzed and compared for their activities. |
S0021967319310866 | Oligosaccharides are gaining importance because of their beneficial properties in human health . They normally appear in natural and synthetic products as complex mixtures of different monomeric units glycosidic linkages and degrees of polymerization being disaccharides and trisaccharides usually the most abundant ones . Although liquid chromatography mass spectrometry is a useful technique for oligosaccharides analysis the similarity of their structures makes difficult their characterization . Moreover there is still scarce information about the relationship between carbohydrate chemical structure mass spectra and chromatographic data . Then in this work chromatographic parameters for 23 disaccharides with different linkages and monomeric units were determined using porous graphitized and hydrophilic interaction liquid chromatography columns . Moreover diagnostic ions of these disaccharides obtained by tandem mass spectra MS | Chromatographic behavior of 23 disaccharides on HILIC and PGC columns was evaluated. MS. characteristic ions of disaccharides were established by SLDA. Structural characterization of trisaccharides was successfully achieved by SLDA application. |
S0021967319310878 | In spatial multi dimensional liquid chromatography devices the flow of each dimension has to remain in the corresponding region otherwise the separation efficiency is undermined . Adequate flow confinement measures are necessary . Here the use of permeability differences across different compartments of spatial two dimensional and three dimensional LC devices as a method to guide fluid flow and reduce analyte loss during the first second and third dimension development was investigated with computational fluid dynamics simulations . In case of 2DLC devices it was shown that porous barriers with a permeability on the order of 10 | Flow control and confinement are necessary in spatial 2D and 3DLC. In 2D. LC devices total spillage under 1 achieved with porous barriers. 3D. LC devices with a highly permeable monolith in the. D and 1m particles in. D. A novel 3D. LC flow distributor is proposed. Design exploration through computational fluid dynamics is utilized. |
S002196731931088X | The migration of bisphenols can take place from plastic packaging materials into freshly cooked takeaway food especially at high temperatures . In this study cetyltrimethylammonium bromide | had been prepared by a one pot hydrothermal method. was used as adsorbent for dispersive solid phase extraction of BPs. The migration of BPA and BPAF from plastic packaging materials was test. |
S0021967319310891 | This research focuses on retention mechanisms in a LC column with C18 stationary phase when novel eluent additives are used . The retention factors between novel eluent additives and conventional ones like ammonium acetate and ammonium bicarbonate at different eluent pH values were compared . A simple set of drug like molecules widely spread over different logP values containing protonated and deprotonated acids and bases was selected for this investigation . HFIP HFTB NFTB and PP demonstrated strong influence on basic polar analytes in basic medium . These additives drastically increased retention . A decrease in retention was observed for acidic analytes when novel eluent additives were used . Additionally for the first time the absolute pH pH | Introduction of 5 novel volatile compounds as eluent additives. Insights to retention mechanisms with ion pairing fluorinated eluent additives. Fluorinated eluent additives aid the retention of bases but reduce it for acids. Promising perspective for drug analysis using LC MS. |
S0021967319310908 | The bottleneck of analytical instrument itself and non ideal instrumental performance will produce a certain degree of drifts between the measured isotopes and the true values . An AAID IC algorithm was thereby proposed to keep the isotopic distributions more accurate in hyphenated instruments e.g . Gas Chromatography Liquid Chromatography Mass Spectrometry . During this data mining process chemical information will be fully used from dozens of data points in retention time | Average was automatically performed for all sampling points in. zones. Automatic resolution and calculation for overlapped isotopes. Calibration functions were established from natural references. The corrected values were transformed into an ionic isotopic curve. AAID IC algorithm was developed for any type of GC LC MS. |
S002196731931091X | The development and application of non porous and porous sorptive rods comprised of polydimethylsiloxanemicrodiamond composites is reported . The PDMS MD composites were made porous using inorganic salt NaCl and NaHCO | Preparation and purification of porous and non porous PDMS microdiamond composites. Evaluation of unique physical chemical characteristics of the PDMS microdiamond composites. Application of the composites as new sorptive phases for organic chemical analysis. |
S0021967319310921 | Gradient elution in liquid chromatography reduces the analysis time improves the efficiency and increases the peak capacity . The study of this chromatographic mode has been based mainly on kinetic dispersion models . The plate model has been applied to a lesser extent despite being the basis for the concepts of plate height and chromatographic efficiency . In this work a general equation describing peak dispersion in HPLC gradient elution is derived from the plate model . This equation is studied and validated for three types of gradients a reference gradient without ramp in which the retention factor varies with time identically throughout the column a gradient of stationary phase in which the nature of the stationary phase varies continuously inside the column resulting in a ramp of constant retention factor over time and finally a mobile phase gradient which produces a retention factor ramp that varies over time . In the latter case the results are similar to those derived from the mass transport equation in linear solvent gradients when the linear solvent strength model is applied . The final equations are expressed based on the initial and final instantaneous retention factors thus they can be applied independently of the deviation of the elution model being fully compatible with isocratic elution . Results predicted with the proposed equations are identical to those obtained by numerical resolution of the elution differential equation system . The additional compression due to the presence of a ramp of modifier is also verified . However useful compressions will appear only when the retention factor changes with time . Finally the study indicates that the extra column variance undergoes a compression process when the retention factor varies over time whether or not there is a ramp inside the column . | The plate model is solved for gradient elution. A general dispersion equation is proposed for isocratic and gradient elution. Gradients with ramp of stationary phase and mobile phase are considered. Peak compression is verified with a ramp of mobile phase within the column. Experimental and predicted values agree satisfactorily. |
S0021967319310969 | To fully capture the chemo diversity of medicinal plants is very essential for understanding of their pharmacological activities and guiding scientific quality control . Aiming to facilitate chemical characterization and novel natural products discovery the present study proposed an integrated approach based on two dimensional liquid chromatography coupled with quadrupole Orbitrap mass spectrometer . An offline comprehensive two dimensional LC system was constructed to cover and separate multi type constituents by combining hydrophilic interaction chromatography and conventional reversed phase C18 . A two step mass defect filtering induced exclusion list data dependent acquisition was developed to increase MS MS coverage and selectivity . Additionally an efficient interpretation strategy combining an automatic matching algorithm and molecular networking was introduced for rapid recognition of known compounds and efficient elucidation of unreported ones . As a case study the integrated approach was tentatively applied for comprehensive characterization of complex multi type components in Lonicerae Japonicae Flos a traditional Chinese medicine . Consequently a total of 537 compounds were characterized from LJF including a large number of potential novel structures . It was demonstrated that the integrated approach is powerful in deep investigation on chemical diversity of medicinal plants and discovery of novel structures . Its application could also be extended for global profiling of other complicated chemical systems such as Chinese medicinal formulas . | A HILICRP LC was applied to cover and separate multi type constituents in LJF. A two step MDF induced exclusion list DDA scan method was developed. An automatic matching algorithm was proposed for targeted screening. Molecular networking was applied for structural classification and elucidation. Global characterization of multi type compositions in LJF was conducted. |
S0021967319310982 | Due to the trace levels of polycyclic aromatic hydrocarbons in soil and the complexity of soil matrices effective sample pretreatment methods are of great significance to obtain accurate analytical results . In this paper polydopamine encapsulated Fe | More facile preparation method was employed to synthesize Fe. The prepared material displayed higher selectivity towards PAHs than. alkanes. The new cleanup process required less time adsorbent and solvent consumption. The proposed method had good cleanup efficiency selectivity and accuracy. |
S0021967319310994 | The objective of this paper was to extend comprehensive theoretical and experimental investigations at the molecular level to identify factors responsible for the high selectivity of imprinted sorbents . This knowledge was utilized in a new analytical strategy devoted to the analysis of hordenine in human urine after beer consumption . Among the various polymeric compositions tested the most effective material was built up from methacrylic acid and ethylene glycol dimethacrylate MIP | Highly selective imprinted sorbent for hordenine was constructed. Selective response of material was proved theoretically and experimentally. Characterization of material was provided. Analytical strategy for determination of hordenine was validated. Method was proved by analysis of hordenine in urine after beer consumption. |
S0021967319311136 | A novel restricted access media magnetic molecularly imprinted polymers was prepared as magnetic solid phase extraction material for tetracyclines . The RAM MMIPs can not only specifically adsorb target molecules in samples but also effectively eliminate the interference of protein macromolecules . The protein exclusion rate is 99.4 . Besides RAM MMIPs have a uniform imprinted and hydrophilic layer rapid binding kinetic high selectivity and larger adsorption capacity . The M SPE was coupled with HPLC UV to extract TCs from untreated milk and egg samples and several major factors affecting M SPE efficiency were optimized . Under optimized conditions the developed method achieved good linearity R | RAM MMIPs were prepared as M SPE material for selective extraction of trace TCs. RAM MMIPs possess satisfactory protein exclusion properties. The method extract TCs directly from untreated milk and eggs successfully. |
S0021967319311148 | Ion exchange chromatography is extensively used in the purification of biological compounds . Reliable mathematical models describing this chromatographic technique are available and can be used to improve the performance of this separation step . However the use of synthetic mixtures for model development hampers the application of this approach with real cell extracts processed in downstream operations . This work presents an original approach for handling non synthetic genuine mixtures of proteins which was applied in the purification of an untagged recombinant pneumococcal surface protein A . First evaluation was made of the efficiency of steric mass action and modified Langmuir isotherms which were separately used together with the equilibrium dispersive model . The data used for parameter estimation and model validation were obtained from anion exchange chromatography runs applied to real cell extracts produced by different cultivation strategies . Simulations showed that the models were able to describe the complex mixtures of unknown proteins . Next the EDM and SMA approaches were used to separately describe the profile of PspA4Pro and the pool of protein impurities eluted together . The simulations showed that PspA4Pro tended to elute at the beginning of the peak enabling the establishment of an alternative elution schedule that provided a 34 increase in the purity achieved using the anion exchange chromatography . | Describe an approach to model protein purification from real cell extracts. Simulate and test models for ion exchange chromatography using software EMSO. Approach applied to the purification of an untagged recombinant PspA. Model simulations enhance PspA purity in 34 . Approach can be extended to any kind of complex protein mixtures. |
S002196731931115X | Being performance enhancing hormones endogenous anabolic androgenic steroids are banned from most competitive sports by the World Anti doping Agency . In anti doping control laboratories routine assays are mainly performed on urine samples of athletes in and out of competitions . Serum constitutes a promising alternative to urine as it is less subjected to manipulation or contamination that may influence the method sensitivity . The simultaneous determination of EAAS including conjugated metabolites using LC MS is very challenging due to their contradicting chemical behaviors at the ionization interface of the mass spectrometer . This may prejudice their detection or limit the method sensitivity . Herein we have addressed these challenges and developed a new method for the simultaneous determination of unconjugated sulphate and glucuronide conjugated EAAS in human serum using ultra high performance liquid chromatography coupled to high resolution mass spectrometry . The use of mass spectrometric detection in full scan mode facilitated the study of the most versatile adducts for detection and quantitation . A solid phase extraction method was developed for the sample preparation prior to analysis . The method limits of quantitation ranged from 0.006 to 7.904ng mL and the recoveries ranged from 70.2 to 96.5 . The method calibration was performed in untreated serum representing realistic matrix composition with correlation coeffecients ranged from 0.9859 to 0.9988 . Finally the serum levels of the investigated steroids were determined in 4 male and 1 female human subjects to provide estimates of baseline levels based on individual values . | A UHPLC HRMS method was developed for simultaneous EAAS analysis in human serum. A solid phase extraction method was developed for EAAS extraction from serum. The method was validated for application to doping routine analysis. The method was applied to estimate baseline levels of EAAS in healthy subjects. |
S0021967319311161 | Application of the superficially porous particles grafted with chiral selectors can substantially improve resolution in chromatographic techniques . In this work we carried out a deeper study on supercritical fluid chromatography systems with 2.7m SPPs bonded with teicoplanin and vancomycin . Fast separations of the majority of enantiomers of phytoalexins substituted tryptophans and ketamine derivatives as representatives of important biologically active and structurally diverse chiral compounds have been achieved . The chromatographic behavior of the structurally different analytes served to characterize these separation systems . The influence of separation conditions namely mobile phase composition i.e . type of co solvent and additive on retention enantioselective resolution and enantioselectivity was examined . The success rate of baseline and partial separations in individual groups of compounds differed with the chiral stationary phase and also with mobile phase composition . The best baseline separations for the phytoalexins were achieved on the TeicoShell column using methanol as a co solvent and trifluoroacetic acid as an additive if used . Mostly partial separations were achieved on the vancomycin based column for all groups of analytes . Complementary separation behavior of these CSPs was confirmed for the majority of the chiral compounds examined in this work . | TeicoShell and VancoShell columns with superficially porous particles in SFC. Effect of co solvents and additives on retention and enantioseparation. Complementary behavior of TeicoShell and VancoShell columns. Enantioselective separation of five groups of biologically active analytes. |
S0021967319311173 | Diffusion inside pores is the rate limiting step in many preparative chromatographic separations and a key parameter for process design in weak interaction aqueous chromatographic separations employed in food and bio processing . This work aims at relating diffusion inside porous networks to properties of stationary phase and of diffusing molecules . Intraparticle diffusivities were determined for eight small molecules in nine different stationary phases made from three different backbone materials . Measured intraparticle diffusivities were compared to the predictive capability of the correlation by Mackie and Meares and the parallel pore model . All stationary phases were analyzed for their porosity apparent pore size distribution and tortuosity which are input parameters for the models . The parallel pore model provides understanding of the occurring phenomena but the input parameters were difficult to determine experimentally . The model predictions of intraparticle diffusion were of limited accuracy . We show that prediction can be improved when combining the model of Mackie and Meares with the fraction of accessible pore volume . The accessible pore volume fraction can be determined from inverse size exclusion chromatographic measurements . Future work should further challenge the improved model specifically widening the applicability to greater accessible pore fractions with corresponding higher intraparticle diffusivities | Intraparticle diffusivity measured for nine stationary phases and eight molecules. Stationary phases were series of Dowex Sephadex and Toyopearl. Measured pore characteristics particle porosity pore size distribution and tortuosity. Calculations with parallel pore model and relation of Mackie and Meares. Improved prediction by combining relation of Mackie and Meares with accessible pore volume. |
S0021967319311203 | Conventional gas chromatography mass spectrometry takes 2040min per sample which is undesirably slow in any application if speed can be increased while still meeting analytical needs . In this study we achieved reasonably good separations with full analysis cycle times of less than 1min by combining for the first time low pressure GC MS with low thermal mass resistive heating for rapid temperature ramping and cooling of the capillary column . The analytical column is threaded into the LTM thin walled metal tubing in an instrumental device known as LTM Fast GC that is mounted at the top of the gas chromatograph in a detector port . The column inlet and outlet are connected to the GC injector and MS transfer line as usual . For LPGC MS a 40cm 0.1mm . i.d . uncoated flow restrictor capillary connected at the injector is coupled with a 2.6m 0.25mm i.d . 0.25m film thickness analytical column leading to the MS . Thus the inlet operates at normal GC pressures but the analytical column is under vacuum which increases the optimal helium carrier gas flow velocity thereby increasing speed of full range separations while maintaining acceptable quality of chromatography . This column configuration in LTM LPGC MS trades a 64 fold gain in speed of analysis vs. standard GC MS for a 4 fold loss in chromatographic peak capacity thereby converting analysis time from minutes into seconds in common applications . For example jet fuel containing fatty acid methyl esters was separated in 25s with 1min full analysis cycle time . An EPA Method 8270 mixture of 76 analytes was also analyzed in 1min full cycle time by LTM LPGC MS. Other examples include very fast analysis of heroin in a street drug powder and elucidation of a new organic synthetic compound . In this report we describe and discuss the several advantageous and practical features of LTM LPGC MS as well as its trade offs . | We report the novel and useful LTM LPGC MS technique for the first time. A new working instrument for real world application was developed. LTM LPGC MS concepts features and trade offs are described and evaluated. Example applications with 1min analysis cycle times are demonstrated. Comparison of LTM LPGC MS is made with conventional fast GC MS. |
S0021967319311227 | An ultrasensitive microchip electrophoresis chemiluminescence assay platform based on separation assisted cascade signal amplification was developed for detection of trace biomolecules . In this work the aptamer was used as a target probe to bindtargetmolecule and triggering cascade signal amplification reaction . The horseradish peroxide labeled DNA was used as signal probe utilizing nucleic acid hybridization and exonuclease cutting technology realized ultrasensitive detection of biomolecules on the MCE CL assay platform . Taking gamma interferon as a model analyte the linear range for IFN detection is 8.010 | An ultrasensitive microchip electrophoresis chemiluminescence assay platform was developed. The assay was based on separation assisted cascade signal amplification to enhance sensitivity. This protocol provides a new platform for the detection of trace biomolecules. The method showed very high sensitivity the detection limit is 1.6 fM and good selectivity. |
S0021967319311239 | A novel miniaturized sample preparation device with braid type extraction medium was successfully developed . Introducing a set of bundles of fine synthetic filaments as the materials of the braid type extraction medium and also the application of an appropriate tension during the braiding process the outer diameter of the resulting braid has been controlled . Optimization of the tension enables an easy preparation of a group of braids that can be well compatible to various internal diameters of capillaries to be packed . The extraction conditions were systematically optimized and the efficient extraction was confirmed under the optimized conditions . All the parameters affects the desorption efficiency were also optimized where typical extraction efficiency was more than 90 for the extraction of phenanthrene in water . The extracted analyte was desorbed sufficiently by employing a sequential pumping process of two organic solvents . During the preparation of the braid a different type of fibrous materials could be inserted to the opening at the center of the braid . Taking advantage of this feature of the braid a stainless steel wire was inserted into the center of the braid . By applying low voltages to the stainless steel wire a heat assisted desorption of the extracted analyte was also studied . Experimentally complete desorption was obtained with the voltage application of 2V . The lowest limit of quantification and the lowest limit of detection for phenanthrene were 0.048 and 0.014g mL respectively . | Miniaturized sample preparation with braid type extraction medium was developed. The extraction capillary was prepared using the braid with a metal wire inside. Applying low voltages to the metal wire a heat assisted desorption was made. |
S0021967319311240 | The ferrofluid phase was prepared according to mixing magnetic nanoparticle and the hydrophobic deep eutectic solvent as a green microextraction solvent . This new composite was applied for vortex assisted dispersive liquidliquid microextraction of doxycycline residual extraction and determined through high performance liquid chromatography ultraviolet . The characterization of magnetic nanoparticle was investigated by XRD TEM and FESEM . The dependency of DOC microextraction to main variables and their interaction and find optimum points were undertaken using response surface methodology with either central composite design . Thus the optimum pH ionic strength ferrofluid volume and vortex time for DOC extraction are determined to be 3.0 4 w v 150L and 7min respectively . According to this condition linear response is found to be greater than 10400ngmL | Application of hydrophobic deep eutectic solvent as the carrier for ferrofluid. Pre concentration and determination of doxycycline in biological samples. Application of VA HDES ferrofluid DLLME based on experimental design optimization. |
S0021967319311252 | Thermodynamic modeling of GCGC separations provides a tool for rapid method evaluation and optimization . Separations of 95 hydrocarbons on two cryogenically modulated GCGC systems are modeled displaying average second dimension retention time modeling absolute errors of 0.17s and 0.12s respectively and generating modeled chromatograms which sufficiently represent experimental data . A web based GCGC modeling routine is presented which allows users to model separations currently focused on hydrocarbons with full control over all system parameters . The method translation capabilities of the application are further demonstrated by replicating Piotrowski etal.s GCGC HRT temporal distribution plots of hydraulic fracturing flowback fluid hydrocarbons . | A web based GCGC modeling application is presented. Hydrocarbon separations can be modeled with full control of system parameters. Modeling accuracy is shown across two GCGC systems. GCGC HRT hydrocarbon temporal distribution plots are replicated. |
S0021967319311264 | S9570 Fe a modified chelating resin containing sulphonated monophosphonic acid bifunctional groups was used for the fluoride removal from aqueous phase for the first time . The results specified that S9570 Fe exhibited better adsorption towards the fluoride ions as compared to the other commonly used chelating resins having monofunctional group such as iminodiacetic acid sulfonic acid or carboxylic acid . Adsorption thermodynamic and kinetic studies of S9570 Fe chelating resin for the fluoride also have been carried out . The thermodynamic results demonstrated that the adsorption was a spontaneous process accompanied with a gradual decrease in entropy and the low temperature was favorable for the fluoride ion adsorption . The kinetic experiments showed that the resin exhibited a rapid initial adsorption behavior and the adsorption process more complied with the pseudo second order reaction model which indicating that the whole adsorption process was controlled by a combined mechanism of intraparticle diffusion and chemical sorption . Adsorption mechanism of S9570 Fe resin for fluoride ions was predicted . The study demonstrated the effectiveness of the phosphoric sulfonic acid bifunctional group chelating resin to remove fluoride and provided a novel type removal method for the fluoride . | A novel chelating resin with bifunctional groups was applied for fluoride removal. Resin exhibited better adsorption to fluoride compared with commonly used resins. Adsorption mechanism of the present resin for fluoride was speculated. |
S0021967319311288 | Short peptides namely di tri and tetra peptides have been proven to play an important diagnostic role in several diseases . Therefore the development of an analytical approach for their detection and identification is nowadays an important research goal . This paper describes an analytical procedure able to overcome the issues of short peptide isolation clean up and identification in plasma samples . Four different protocols were compared and tested to maximize both recovery and total number of identifications of short circulating plasma endogenous peptides . The purified peptides coming from the four different tested protocols were separated by zwitterionic hydrophilic liquid chromatography coupled to high resolution mass spectrometry with the purpose of accomplishing an untargeted investigation based on suspect screening for short peptides in plasma . In particular the use of Phree Phospholipid removal cartridge in combination with a purification step by solid phase extraction on a graphitized carbon black sorbent allowed the identification of the largest number of amino acid sequences . The clean up procedure allowed to tackle the issue of the low abundance of such peptides and their suppression during mass spectrometric analysis . The results indicated that sample preparation is therefore fundamental for short peptide analysis in plasma samples . | Development of an efficient clean up strategy for short peptides in plasma. Comparison of 4 different clean up protocols advantages and disadvantages . Untargeted peptidomic approach for short peptide identification in plasma. Identification of 91 short peptides the largest number never identified before. Development of a rapid and simple method for clinical applications. |
S002196731931129X | In recent years supercritical fluid chromatography has become a powerful tool in modern analytical chemistry and the diversity of stationary phases in SFC promotes phenyl type phases to confront with a significant resurgence of interest . In this paper a series of phenyl type stationary phases with different substituted benzenes involving N propylbenzamide 4 fluoro N propylbenzamide and 4 ethyl N propylbenzamide were synthesized . Retention mechanism of these phases in SFC was investigated using a linear solvation energy relationship model . The phenyl type stationary phases with all positive parameters can provide all types of interaction typically involving hydrogen bonding dipole dipole and dispersive interactions . The different benzene s substituents of the stationary phases mainly affected their hydrogen bonding and dipole dipole interactions which could be reflected by the angle between the solvation vectors to some extent . The | Using LSER for evaluation of phenyl type phases to extend their applications in SFC. Electron withdrawing or donating groups causing different. and. coefficients. angles and. plot showed different selectivity among phenyl type phases. Construction of two systems with 63.49 orthogonality based on 25 phenolic compounds. Ten flavonoids were separated at suitable condition on the phenyl type phases. |
S0021967319311306 | Polychlorinated dibenzo p dioxins and furans offer a complex separation challenge due to their chemical similarity and 5020 possible congeners including the Br Cl congeners . Not only are these compounds difficult to separate but they are also difficult to identify . Expensive reference materials are needed for conventional dioxin analysis usually requiring | Characterization of 9 modern and popular GC columns for dioxin analysis. Full elution orders for all 136 tetra octa chlorinated dioxins and furans. Retention index database for 136 chlorinated dioxins and 32 mixed halogenated dioxins. Selectivity and orthogonality comparisons for 8 modern GC columns for dioxin analysis. |
S002196731931132X | Byproducts from artichoke represent the majority of the mass collected from the plant and constitute an interesting source of bioactive compounds such as inositols and caffeoylquinic acids . In this work a microwave assisted extraction methodology was developed for the simultaneous extraction of these compounds from artichoke stalks leaves receptacles and external bracts . Optimal MAE conditions to maximize the extraction of these bioactives and the antioxidant activity were 97C 3min ethanol water . Moreover a GCMS methodology was also developed for the simultaneous determination of these compounds in a single run optimal derivatization conditions were achieved using hexamethyldisilazane and | Inositols and caffeoylquinic acids from artichoke were analyzed by GCMS. Regarding derivatization best results were achieved with HMDS and BSTFA 1 TMCS. A MAE method was optimized for extraction of these bioactives from artichoke bracts. Optimal conditions were applied to different artichoke byproducts. Receptacles were the richest in caffeoylquinic acids and leaves were in inositols. |
S0021967319311331 | Profiling the spatial distributions and dynamic changes of metabolites in plant tissue is critical to elucidate the complex metabolic regulation during plant growth development and responses to abiotic or biotic stresses . In this study we developed a high coverage MALDI MS imaging method to visualize the spatial locations of a wide spectrum of metabolites in | A high coverage MALDI MSI method was developed for plant tissue analysis. BNDM was optimized as a new matrix for MALDI MSI of. Acetone washing improves the sensitivity of MALDI MSI. Spatial feature and dynamics of metabolites in. were imaged. |
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