Filename
stringlengths 17
17
| Abstract
stringlengths 76
3.38k
| Highlights
stringlengths 80
1.73k
|
|---|---|---|
S0021967319311343
|
An update for ASTM D2425 Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry was recently released to expand its scope by adding modern mass spectrometric instrumentation and a new sample type synthesized hydrocarbons . While the method update is a proper step towards modernization it still lacks validation parameters . The description of the updated standard method contains precision estimations but no consideration for a possible bias meaning that the method accuracy was not evaluated . The 2019 update does not either provide the lowest concentration of an analyte that can be detected and quantitatively determined limit of detection and limit of quantification . In the present study the LOD LOQ and bias were evaluated as an intra laboratory study . The LOD and LOQ determination was based on the adjusted standard deviation of the least abundant hydrocarbon type in a sample and were 0.004 and 0.01w w in renewable jet fuel and 0.01 and 0.02w w in gas oil respectively . The bias was determined by measuring relative hydrocarbon recovery percentages for spiked samples . The renewable jet fuel was spiked with cycloparaffins and alkylbenzenes and the recovery percentages were 140 and 63 respectively . The gas oil was spiked with paraffins and alkylbenzenes and the recovery percentages were 117 and 90 respectively . Both sample sets were positively biased for paraffin content and negatively biased for alkylbenzene content . Based on above results this method may not work well for RJF samples .
|
The LOD was 0.004wt and the LOQ was 0.001wt for renewable jet fuel. The LOD was 0.01wt and the LOQ was 0.02wt for gas oil. Both sample sets were positively biased for paraffin content. Both sample sets were negatively biased for alkylbenzene content. The ASTM D2425 method may not work well for renewable jet fuel samples.
|
S0021967319311410
|
Steroid hormones are a type of crucial substances that mediate numerous vital physiological functions . The comprehensive detection of steroid hormones can help understand the physiopathologic mechanism of steroid hormone related diseases . It is very difficult to determine steroid hormones in biological samples due to their low endogenous concentrations and poor ionization efficiency . In this study an efficient and sensitive approach was developed for profiling steroid hormones by combining liquid liquid extraction and parallel derivatization with liquid chromatography tandem mass spectrometry . Methoxyamine and dansyl chloride were used to derivatize steroid hormones containing carbonyl and phenolic hydroxyl groups respectively . Our established method achieved simultaneous analysis of carbonyl and phenolic hydroxyl containing steroid hormones and could cover estrogens androgens corticoids and progestogens . Twenty nine steroid hormones were detected at pg mL levels with the sensitivity enhanced by three orders of magnitude after derivatization . The linearity precision and recovery were satisfactory for quantitative analysis of steroid hormones . Finally the established method was successfully employed to the determination of steroid hormones in serum samples of healthy males and females as well as ovarian cancer patients . The results showed that this approach was suitable and reliable for routine test of steroid hormones containing carbonyl and phenolic hydroxyl groups .
|
A parallel derivatization strategy for steroid hormones was newly proposed. The approach has a broad coverage of steroid hormones. The sensitivity of the method was greatly improved by three orders of magnitude.
|
S0021967319311422
|
To monitor the existing and emerging halogenated carboxylic acids in drinking water a sensitive and rapid ultra high performance liquid chromatography quadrupole orbitrap high resolution mass spectrometry method for simultaneous target quantification of 10 haloacetic acids and semi target screening of 19 HCAs was developed . After filtration drinking water samples were injected into the instrument . HCAs were separated on an HSS T3 column and detected by a type of non target scan in the electrospray ionization negative mode . For target quantification of 10 HAAs good linearity was obtained and the correlation coefficients were higher than 0.995 . The limits of detection were in the range of 0.0502.0g L. The recoveries were in the range of 89.7 108 83.4 121 77.1 116 and 80.2 104 at levels of 2.5 5.0 10 and 20g L respectively with relative standard deviations of 1.26 16.9 . For semi target screening of 19 HCAs several criteria including accurate
|
A rapid UPLC Q Orbitrap HRMS method for target quantification and semi target screening of HCAs was developed. g L sensitivity was obtained when the sample was directly injected for analysis. The semi target screening strategy was shown successfully by reference standards. 13 suspect HCAs and 5 target HCAs were detected in drinking water which DCAA and TCAA in some samples exceeded the limits suggested by the EPA and WHO.
|
S0021967319311434
|
With the increasing demand for lipase inhibitors and new drugs used in the clinical treatment of obesity it is of great significance to screen lipase inhibitors from traditional Chinese medicines via capillary electrophoresis . In this work Fe
|
Fe. @TiO. nanoparticle was fabricated as magnetic support of immobilized lipase. A capillary electrophoresis method was established for screening lipase inhibitors. and its compounds were firstly reported as lipase inhibitors.
|
S0021967319311446
|
A simple magnetization method was developed for the preparation of magnetic materials from conventional solid phase packing though coprecipitation and solvothermal approaches . And the prepared magnetic materials were used for magnetic solid phase extraction of biogenic amines from beers . Furthermore to improve the analytical throughput a solid phase on situ quadraplex isotope dimethyl labeling method was developed for the quantification of BAs by liquid chromatography high resolution mass spectrometry LC
|
An efficient method for preparation of magnetic solid phase adsorbent. A more favorable labeling method based on solid phase on situ labeling. A multiplex dimethyl labeling for more efficient analysis of biogenic amines.
|
S0021967319311458
|
Mineral oil hydrocarbons are used in the consumer goods sector for the elaboration of a wide range of foods and cosmetics . Traditional methods for determining their levels and composition are time consuming and laborious besides requiring complex instrumentation . Here a simple and fast method was developed that uses columns packed with silver modified silica in supercritical fluid chromatography with flame ionization and UV detection for the determination of mineral oil saturated hydrocarbons and mineral oil aromatic hydrocarbons in purified mineral oil samples . The method requires no sample preparation apart from dilution . Direct quantification of MOSH and MOAH was possible for samples with MOSH MOAH ratios around one . For other samples deconvolution of the MOSH and MOAH humps in the FID chromatogram using the UV signal was needed since baseline separation of the two fractions could not be obtained . Validation of the method performance showed an excellent linearity
|
Direct MOSH MOAH quantification can be done by SFC FID UV. MOAH detection limits were better than 0.36 . SFC FID UV has an excellent linearity and a better repeatability than the standard methods. SFC FID UV is suitable for samples with viscosities and molecular weights below 56mm. and 450gmol
|
S002196731931146X
|
Developing highly selective stationary phases is essential to address the issues for separation of analytes with similar properties and various components in complex samples . Herein we report a new triptycene based material functionalized with polycaprolactone moieties as the stationary phase with high resolution performance for gas chromatography . The TP PCL capillary column exhibited column efficiency of 5555 plates m and moderate polarity . On the column dozens of mixtures of positional and structural isomers can be well resolved involving benzene derivatives with varying substituents naphthalene derivatives alkanes and alcohols . It exhibits advantageous performance for high resolution of the critical pairs of alkylbenzenes phenols anilines and alkanes over the PCL column and commercial DB 35 MS column with similar polarity . Moreover the TP PCL column showed excellent separation repeatability and reproducibility with RSD values of 0.02 0.07 for run to run
|
Triptycene based stationary phase functionalized with polycaprolactones TP PCL . Integrated advantages of 3D rich triptycene framework with PCL moieties. High resolution of the critical isomers of xylenes anilines phenols and alkanes. Improved selectivity and thermal stability over the PCL column. Good potential for practical analysis of complex samples.
|
S0021967319311471
|
It is challenging to greatly increase of the extraction selectivity and efficiency by stir bar sorptive extraction of ultra trace polychlorinated biphenyls in complex environmental matrix e.g . soils . To fulfill this purpose one of the critical works is to prepare some coatings with high selectivity adsorptive capacity and reusability . It is also important to develop some green simple methods for preperation the coatings . In this work a kind of highly efficient and bioactive coating based on hyperbranched aptamer was constructed
|
A hyperbranched aptamer coating was constructed on a magnetic stir bar with ease. The bioactive coating shows high adsorption capacity and specificity towards PCBs. The stir bar was used to headspace extract and detect ngg. of PCBs in soils. The assay is facile green and effective to detect trace PCBs in complex samples.
|
S0021967319311483
|
Oligonucleotide based medicines that can modulate gene expression have numerous potential applications in targeted therapies . Most of the commercialized therapeutic oligonucleotides are chemically modified to increase their
|
Optimization of two complementary separation techniques to analyze oligonucleotides. Successful coupling of HILIC and CZE to drift tube ion mobility QTOF. Use of collision cross section measurements to determine the number of nucleotides.
|
S0021967319311501
|
In the present work NiFe layered double hydroxide Nylon 6 composite nanofibers were prepared by electrospinning method and used as a new sorbent for the extraction and measurement of non steroidal anti inflammatory drugs in whole blood samples . The method is based on micro solid phase extraction by packed sorbent followed by HPLC UV analysis . Effective parameters on the extraction efficiency were optimized using a central composite design . In order to characterize the sorbent Fourier transform infrared spectroscopy thermogravimetric analysis field emission scanning electron microscopy energy dispersive X ray analysis and elemental mapping were applied . The method was fully validated based on linearity limits of detection and quantification precision and recovery . Under the optimal conditions LOD values were found to be 25ngmL
|
NiFe layered double hydroxide Nylon 6 composite nanofibers were fabricated. Electrospinning was applied to prepare the composite nanofibers. The composite nanofibers were used as a sorbent for micro solid phase extraction. A packed sorbent in a spinal syringe was used as a setup for extraction. The method was applied for simultaneous determination of NSAIDs in blood samples.
|
S0021967319311513
|
In general the simultaneous separation and isolation of compounds with a broad polarity range from natural products is a challenge by ordinary high speed counter current chromatography . Indeed the complex solvent system screening methods limit the broader application of HSCCC . We describe herein a rapid and efficient linear gradient CCC method that enables the separation of flavonoid glycosides with a broad range of
|
Linear gradient CCC was developed to separate broad range of. value compounds. Inner recycling CCC was further used for the compounds with similar. values. Ethyl acetate. butanol water solvent system is simple for LGCCC separation.
|
S0021967319311525
|
The interest for a better understanding of ion exchange mechanisms at the atomic level has strongly increased over the past decades . Indeed molecular level information about physico chemical mechanisms could help optimizing chromatographic processes for protein purification which are sub optimized due to the lack of predictive models . A promising approach is based on the use of Molecular Dynamics simulations to study local phenomena inside adsorbents which can then be challenged against experimental results . In this work macroscopic experimental data consisting in the ion exchange uptake of
|
The Steric Mass Action SMA model is used to describe single adsorption isotherms. All atom Molecular Dynamics MD simulations are performed. The chromatographic surface is modeled with a counter ion layer. Four binding patches are identified to be the predominant form of adsorption. SMA parameters from MD are in good agreement with macroscopic experiments.
|
S0021967319311537
|
Recently in separation science ionic liquids have been commonly used as modifiers for buffer solutions dynamic coating solutions or coating solutions on carriers in capillary electrophoresis . However only several papers have reported the use of chiral ILs as the sole chiral selector . In this paper a chiral ionic liquid cholinium clindamycin phosphate was synthesized and employed as a sole chiral selector in capillary electrophoresis . A series of parameters affecting the separation were optimized including chiral selector concentration buffer pH proportion of organic modifier as well as the applied voltage . Under the optimal conditions compared to clindamycin phosphate the IL selector showed better enantioseparation capability and improved peak shapes for five racemic drugs . In addition Molecular docking program Autodock was employed to elucidate the chiral recognition mechanism of Ch CP the computing results conformed to the experimental results .
|
A chiral ionic liquid was synthesized and used as the sole chiral selector. The IL selector showed enhanced enantioseparation capability compared with clindamycin phosphate. The chiral recognition mechanism for the chiral selector was investigated by molecular modeling methods.
|
S0021967319311549
|
In recent years covalent organic frameworks play an important role in the field of chromatographic separation . However COFs are used rarely in open tubular capillary electrochromatography so far and the reported methods have not been applied to actual sample analysis . Herein a novel azine linked COF N
|
This is the first time using N. COF as stationary phase for OT CEC separation. BPA and its analogues can be baseline separated by the N. COF coated capillary. The method was successfully used to determine BPA and its analogues in beverages.
|
S0021967319311550
|
Quantitative determination of endogenous compounds in biological samples has still been challenged by the absence of authentic blank matrix . Alternative strategy of surrogate matrix for preparing reference samples are prevalent due to its low cost and high availability . However the evaluation system of surrogate matrix is not perfect . Herein a novel multifunctional isotopic standards based steroidomics strategy was developed . Isotope labeled standards were used not only as internal standards but also for the evaluation the feasibility of surrogate matrix which improved the accuracy of assessment and could provide a new prospect for the quantitative analysis of endogenous compounds . Based on this approach a detailed optimization from LC separation MS detection to extraction conditions for global steroids in the steroidogenesis was firstly carried out . Characteristics and regularities of steroids in LCMS were summarized to make references for further targeted or untargeted steroidomics study . Then eighteen steroids were quantified with high accuracy and high sensitivity in plasma from four types of cancer patients and healthy subjects using 1 BSA in PBS as surrogate matrix . And multi steroids indexes with the best discriminating ability for lung colorectal breast and gastric cancer in different genders were identified successfully with Student s
|
Multifunctional isotopic standards based steroidomics strategy was developed. A novel isotopic standards based evaluation system was proposed to test the reliability of surrogate matrix. Characteristics and regularities of global steroids in LCMS were summarized in detail for the first time. Cancer biomarkers were identified successfully using the steroidomics strategy.
|
S0021967319311586
|
Supercritical fluid chromatography is an orthogonal technique to UHPLC . In recent years SFC has demonstrated potential for use in the analysis of a broad variety of analytes of different polarities if modifiers and additives are utilized as additional mobile phase constituents . However to date little research has been carried out on ion exchange separation of highly polar and ionic analytes using SFC .
|
SFC MS MS for highly polar ionic analytes. Ion exchange column as stationary phase. Drugs and metabolites for doping control analysis and forensics. Systematic method development.
|
S0021967319311598
|
The research of natural active substances is facing the problems of low separation efficiency and active component loss due to the complex composition of natural extracts . In this study a strategy based on liquid liquid refining extraction and high speed counter current chromatography was established to solve this problem . Separation of an active compound with the amylase inhibitory activity from
|
Liquid liquid refining extraction assisted the bioassay guided separation. Consecutive HSCCC was used to prepare the active compound. Separation efficiency was improved. Luteolin with amylase inhibitory activity was obtained from. Theoretical explanation of luteolin against amylase was studied by docking.
|
S0021967319311604
|
Triazine rings containing porous aromatic framework was synthesized through a Friedel Crafts reaction and investigated as a coating for the stir bar sorptive extraction of interest triazines . The triazine rings and conjugated groups in PAF 56p could interact with triazine rings containing herbicides by hydrophobic and interactions . The PAF 56p coated stir bar showed superior extraction performance over commercial PDMS and EG coated stir bar in terms of extraction efficiency and dynamics towards six triazine herbicides with different polarity . Based on it a method by combining PAF 56p SBSE with high performance liquid chromatography diode array detector was established for the analysis of six target triazine herbicides including simazine atrazine ametryn prometon prometryne and prebane . The affecting factors of SBSE were investigated by single factor test . Under the optimized conditions the limits of detection of the proposed method were ranged from 0.037 to 0.089g L with the linear range within 0.1200g L for six triazine herbicides . High enrichment factors of 61.889.5 fold were achieved . The developed PAF 56p SBSE HPLC DAD method was successfully applied for trace triazine herbicides analysis in maize and maize leaf samples with recoveries in the range of 86.5115 and 85.1114 for spiked maize and maize leaf samples respectively .
|
Triazine rings containing porous aromatic framework PAF 56p was synthesized. Novel PAF 56p coated stir bar was prepared for extraction of six triazine herbicides. It shows excellent extraction performance to target analytes with different polarity. A SBSE HPLC DAD method was developed for trace triazine herbicides analysis in maize. It has a good application potential for analyzing trace triazine herbicides in crops.
|
S0021967319311616
|
Most HPLC enantiomer separations are performed with columns packed with a chiral stationary phase operated with an achiral mobile phase . The intrinsically limited chemical selectivity of most CSPs to the simultaneous resolution of several pairs of enantiomers means that complex mixtures of diverse pairs of enantiomers can not be resolved in a single run due to peak overlapping . Moreover some drawbacks remain when the analyte is present in very complex samples containing other achiral compounds which can co elute with the enantiomer peaks . Multidimensional chromatography becomes an option to increase peak capacity and resolve these samples .
|
Novel LCxLC configuration for enantioresolution of amino acids. Chiral x achiral 2DLC is implemented to determine amino acids profiles. Chiral Quinine phase and C18 are combined to increase separation space. Splitting the. D eluent by an active splitter pump improves the separation quality. Amino acids from honey samples from different origins were determined.
|
S0021967319311628
|
A simple and ecofriendly sample preparation method was developed for quantifying fluoroquinolone antibiotics in surface water . Seventeen combinations of monoterpenes fatty acids and a benzoate ester were utilized for the
|
First. formation of thymol based hydrophobic DESs is reported. Various. formed hydrophobic DESs were tested as extractant in LLME. Fluoroquinolone antibiotics were effectively preconcentrated in hydrophobic DESs. A green and simple sample preparation method was developed and validated.
|
S002196731931163X
|
Surfactants are widely used in various petrochemical applications . Thus it is essential to have highly efficient analytical tools to monitor the different classes of surfactants commonly used . Three among the four known classes of surfactants were studied in the present work anionic nonionic and cationic . Thanks to high resolution mass spectrometry a useful mass list was created including 119m z values . This list was the foundation of a HRMS database which for the sake of simplicity will be further denoted only database . To avoid ion competition and streamline attribution of structural formulas for isobar molecules a suitable chromatographic method was used before MS . The retention behavior of six surfactants was evaluated under three separation modes reversed phase liquid chromatography hydrophilic interaction chromatography and mixed mode chromatography . In RPLC mode six columns were tested including C4 C18 C30 polar embedded C18 PFP and phenyl chemistries . Two HILIC columns were also tested including bare silica and urea chemistries . An anion exchange combined with RPLC mechanism was investigated as mixed mode mechanism . Using ammonium formate at 10mM as buffer provided the best signal in HRMS . In liquid chromatography acid conditions were preferred to avoid peak tailing due to residual silanols . The mixed mode separation mode clearly appears as the best compromise for the characterization of the three surfactants classes . Nevertheless the orthogonality observed for the separations obtained in HILIC and RPLC modes offers some possibilities for further multidimensional separations .
|
Foundation of a HRMS database of polydisperse surfactants. Chromatography behavior of surfactants with three separation modes building of retention maps. Limits of HRMS and one dimension liquid chromatography HRMS for the separation of polydisperse surfactants.
|
S0021967319311641
|
Differences in the characteristics of seventeen commercial C 30 liquid chromatographic columns were studied for the separation of carotenoid isomers . A mixture consisting of nine xanthophyll and hydrocarbon carotenoids were separated under conditions carefully chosen to reveal changes in selectivity . The influence of the mobile phase composition column temperature and mobile phase flow rate were evaluated . Shape selectivity was characterized with Standard Reference Material 869b Column Selectivity Test Mixture for correlation with carotenoid retention behavior . Regular changes were observed across a broad spectrum of shape selectivity characteristics as indicated by SRM 869b . Better separations of carotenoid isomers were achieved with C 30 columns than were possible with C 18 columns even after optimization of separation conditions .
|
C 30 LC columns exhibit unique functional properties not achieved with C 18 columns. Broad selectivity differences occur among commercial C 30 columns. Selectivity trends toward carotenoid isomers follow predictable pathways. Shape recognition varies as a function of column temperature. Van Deemter analysis affords quantitative measures of C 30 mass transfer performance.
|
S0021967319311665
|
The specific and sensitive detection of multiple pathogens is critical for the prevention and identification of health and safety related problems . A microchip electrophoresis LED induced fluorescence method combining an aptamer based probe and a novel universal primer duplex polymerase chain reaction process was designed to simultaneously detect two kinds of bacteria . The probe consists of a recognition unit for specifically capturing bacterial cells and eventually releasing complementary DNAs . The two released DNA strands can be simultaneously amplified by a pair of universal primers because of the identical sequences designed at both ends of the two DNA strands . The UP DPCR products of C1 and C2 can be separated and detected by MCE LIF and the heights of the two peaks are correlated with the concentrations of the corresponding bacteria . Here
|
MCE based aptasensor for simultaneous detection of two kinds of pathogenic bacteria. A novel universal primer was used in duplex PCR for nucleic acid amplification. This method avoids the lysing of bacterial cells and simplifies duplex PCR process. This method shows low LOD and was used in bacteria detection in defatted milk.
|
S0021967319311677
|
Two high throughput steady state methods of counter current chromatography separations conventional and closed loop recycling are proposed evaluated and compared . The methods are based on the application of semi continuous sample loading technique the CCC setup includes two mobile phase tanks one with the pure mobile phase and the second with the sample solution in the mobile phase . The mobile phase pump is periodically switching from one tank to another . The sample solution is continuously loaded into the CCC column over a constant time with the constant volumetric rate equal to the flow rate of the pure mobile phase .
|
High performance modes of counter current chromatography CCC . Analytical expressions allowing the design and simulation. Examples of simulation presented in Mathcad program. Multiple increase in the performance and effectiveness of CCC. Acceptable agreement between theory and experiment.
|
S0021967319311689
|
This article describes a new simultaneous method for the analysis of sulfur type poisons hydrocarbons and permanent gases affecting the productivity of the Ziegler Natta catalyst during the synthesis of polypropylene on an industrial scale in a fluidized bed reactor . The identification was achieved employing a configuration of the seven valve chromatographic system with events at different times allowing distribution of the sample through multiple columns and finally reaching the helium ionization detectors of pulsed discharge flame ionization and mass spectrometry . The results obtained show a good precision of the method used because the variability was less than 1.02 in area and 0.49 in retention time for short term precisin and longer term precision . The quantification of these species was successful after performing the calibration curve with the dynamic mixer showing an
|
New simultaneous method for the analysis of sulfur type poisons hydrocarbons and permanent gases. The identification was achieved using a configuration of seven valves eight columns and three detectors. the variability was less than 1.02 in area and 0.49 in retention time. Productivity losses during polypropylene production were between 5 and 22 .
|
S0021967319311690
|
This paper reports the development of a stationary phase thickness gradient gas chromatography column that enables analyte peak focusing and improves separation resolution . Theoretical analysis and simulation demonstrate focusing via a positive thickness gradient
|
Film thickness gradient along a column to achieve peak focusing. Theoretical model and simulation to understand the underlying mechanism. Experiments conducted with circular and rectangular columns under various conditions. The technique is broadly applicable to various stationary phases and column types.
|
S0021967319311707
|
Despite analytical advances matrix effects in pesticide residue analysis by gas chromatography tandem mass spectrometry continue to be a challenge especially in difficult samples such as seeds . In this study the influence of different clean up sorbents and different mixtures of primary secondary amine C18 graphitized carbon black and MgSO
|
Low moisture seeds of vegetable oil plants with complex matrices were chosen. The clean up sorbents addition of water matrix match calibration were explored. Using PSA C18 GCB MgSO. gave maximum compensation of matrix effects. Time consuming matrix matched calibration was shortened by using one matrix. Residues of 21 pesticides were detected in 26 real seed samples.
|
S0021967319311719
|
The information potential of comprehensive two dimensional gas chromatography combined with time of flight mass spectrometry featuring tandem hard and soft electron ionization is here applied to accurately delineate high quality hazelnuts
|
GCGC TOFMS Tandem Ionization provides accurate fingerprint of hazelnuts metabolome. Tandem Ionization provides complementary information for identity confirmation. Tandem Ionization extends the information potential of GCGC fingerprinting. Fingerprinting results cross validation between tandem signals. Meaningful correlations between primary metabolites and informative volatiles.
|
S0021967319311720
|
The identification and quantification of post translational modifications is a crucial step required during the development of therapeutic proteins . In particular the characterization of charge variants separated by cation exchange chromatography is a tedious process commonly performed with an off line manual fraction collection followed by peptide mapping . To improve the efficiency of this time consuming approach a generic on line multi dimensional LC MS approach was developed for the characterization of various monoclonal antibody isotypes and a bi specific antibody . Fractions collected from
|
Thorough optimization of a multi dimensional LC MS setup to identify charge variants. Similar levels of most protein PTMs reported by off line and on line approaches. Faster turnaround time achieved by on line vs. off line peptide mapping. Ultra fast on column tryptic digestion can limit artificial deamidation.
|
S0021967319311744
|
The performance of the Centrifugal Partition Chromatography as a liquid liquid chromatographic technique depends strongly on the two phase solvent system used . Thereby the individual influence of the retention of the stationary phase the coalescence and the dispersion of the mobile phase in the chambers must be understood to select appropriate solvent systems and reach high separation efficiencies . In this study an optical measurement system was used to investigate the influence of the physical properties of the Arizona solvent systems on the stationary phase retention in descending mode . Therefore physical properties like density viscosity and interfacial tension were measured as well as the stationary phase retention . Using dimensionless numbers a correlation between the stationary phase retention and the influencing parameters could be determined . The correlation was validated using data from the literature . Additionally the solvent systems were modified by additives to identify the validity of the correlation . It was proven that the dimensionless numbers Capillary number and Morton number can be used to predict the stationary phase retention of other liquid liquid solvent systems as well as for different operating conditions .
|
Optical determination of stationary phase retention in centrifugal partition chromatography. Systematic approach analyzing the influences on the stationary phase retention. Correlation with Capillary number and Morton number describing the dependency of stationary phase retention. Correlation in accordance with influences described in literature. Property changes induced by additives also predictable.
|
S0021967319311951
|
A simple effective convenient and environmentally friendly methodology using high throughput bar adsorptive microextraction with microliquid desorption in combination with large volume injection gas chromatography mass spectrometry operating in the selected ion monitoring acquisition mode was applied for the determination of nicotine and cotinine in urine samples . Under optimized experimental conditions the developed methodology allowed for linear dynamic ranges between 20.0 and 2000.0gL
|
A high throughput microextraction technique for the analysis of nicotine and cotinine in urine. A fully optimized and validated methodology with suitable analytical performance. A small apparatus that allows simultaneous microextraction of up to 100 samples. The target compounds were found in the range of 23.62612.6gL. 86 .
|
S0021967319311963
|
In this study a novel magnetic molecularly imprinted polymer was prepared by surface imprinting technology using 2 oxin and 6 HNA as dual virtual templates and 4 vinyl pyridine as the functional monomer for extraction of patulin from the surface of magnetic nanoparticles . MMIPs were characterized by fourier transformed infrared spectroscopy X ray diffraction and vibrating sample magnetometry . The results showed that the molecularly imprinted polymer was successfully coupled with magnetic nanoparticles and could be used as a magnetic selective recognition material . Moreover MMIPs have a greater adsorption capacity for PAT than conventional MIPs . The magnetic dispersion solid phase extraction procedure was optimized and then combined with liquid chromatography tandem mass spectrometry for detection of PAT in juice samples . The method showed excellent analytical performance in terms of linearity ranged between 0.5g L
|
A novel MMIP with specific adsorption of patulin was successfully synthesized. The magnetic dispersion solid phase extraction MDSPE method was established. This approach saves time and consumption of organic reagents. This study provides a new pretreatment method for detection of patulin in juice.
|
S0021967319311975
|
The preparation of a highly efficient chiral liquid chromatography column is explored by dynamically coating a reversed phase porous silicon pillar array column with hydroxypropyl cyclodextrin as the chiral selector . Analyte mixtures composed of non steroidal anti inflammatory drugs were tested to reveal the enantioseparation potential of the column . The mechanism of chiral discrimination was investigated . The adsorbed Hp CDs on the column surface experience different interaction with enantiomers . The chiral stationary phase showed satisfying stability and could be easily restored by recovering the selector with sufficient flushing and repeating the loading procedure . The peak capacity of the column was evaluated and it was found high enough to separate three enantiomer couples using a one dimensional LC technique .
|
A highly efficient chiral liquid chromatography column is obtained by dynamically coating a reversed phase porous silicon pillar array column. Analyte mixtures composed of non steroidal anti inflammatory drugs were tested to demonstrate the enantioseparation potential of the column. The peak capacity of the chiral column was evaluated and was found to be higher than 160.
|
S0021967319311987
|
In the present work we have investigated the combination of hydrophilic interaction liquid chromatography and reversed phase liquid chromatography for the separation of peptides in on line HILIC x RPLC . This combination usually leads to significant solvent strength mismatch since a weak solvent in HILIC becomes a strong solvent in RPLC . This may result in band broadening peak distortion and breakthrough phenomena . Our focus was directed towards the reduction of band broadening and peak distortion . The conditions of the emergence of breakthrough could be investigated with high resolution mass spectrometry detection . The importance of both the injection volume and the difference in composition between injection and elution solvents was highlighted . Reported strategies to avoid bad peak shapes mostly rely either on flow splitting to limit the injection volume or on on line dilution . Here we propose an alternative approach which consists in injecting large volumes in the second dimension . In this case no flow splitting nor dilution prior to the second dimension is required . Our results show that above a certain critical injected volume depending on both the compound and the elution conditions narrow and symmetrical peaks can be obtained despite the persistence of breakthrough . As a result the injected volume in the second dimension must be larger than the largest critical volume . This counter intuitive approach was applied for the on line HILIC x RPLC UV HRMS analysis of a complex tryptic digest sample . A peak capacity close to 1500 could be achieved in 30min which is two fold higher than in RPLC x RPLC within the same analysis time .
|
Injection issues in on line HILIC x RPLC were overcome without flow splitting. Alternative strategy relying on injection of large volumes in. D is presented. Good peak shapes in RPLC above a critical injection volume despite breakthrough. Applicability demonstrated for on line HILIC x RPLC analysis of peptide sample. Effective peak capacity of 1500 in 30min 80 increase compared to RPLC x RPLC .
|
S0021967319311999
|
Biomedical sciences and in particular disease biomarker research demand highly selective and efficient glycoproteins peptides enrichment platforms . In this work a facile strategy to prepare hydrophilic maltose functionalized magnetic metal organic framework loaded with Au nanoparticles denoted as
|
A hydrophilic. was synthesized via a facile synthetic route. The. possessed remarkable hydrophilicity rapid magnetic responses. The. showed the excellent performance on glycopeptides enrichment. The identified glycopeptides from human serum was demonstrated.
|
S0021967319312002
|
Ultra performance convergence chromatography which combines the advantages of both reversed phase liquid chromatography and gas chromatograph is a novel eco friendly analytical method and could be a powerful supplement for RPLC and GC . Based on these characteristics an UPC2 method was developed for the chemical analysis of Gaoben medicinal materials including six batches of
|
An UPC2 method was developed for chemical quality evaluation of Gaobens. Comparative analysis on the chemical constituents of Gaobens by UPC2 and UPLC. Chemometrics analysis on the results of UPC2 showed effective discriminability. The compounds analyzed by UPC2 method showed important chemotaxonomic significance. UPC2 is a powerful supplement to UPLC for chemical quality evaluation in aromatic TCM.
|
S0021967319312026
|
Modelling the retention behaviour of solutes in liquid chromatography based on the composition of the mobile phase is a common task in the chromatographic practice . Along the development of liquid chromatography several models have been proposed to help in understanding the retention mechanisms and especially allow the prediction of retention times with optimisation purposes . Particular models are used for different LC modes such as normal phase reversed phase hydrophilic interaction and micellar . In this work a general equation is proposed that includes a parameter the elution degree
|
An extension of the linear solvent strength model is proposed. A parameter that describes the changes in elution strength is included. A general equation to calculate the compression factor in gradient elution is given. Data obtained from several chromatographic modes are fitted to the model.
|
S0021967319312129
|
Two dimensional gel electrophoresis is a technique that has been widely applied in a variety of proteomics studies . It is capable of resolving complex protein mixtures into individual protein spots based on their isoelectric point and molecular weight enabling large scale analysis of protein expression patterns for deciphering their changes in different biological conditions . 2 DE is a powerful tool that empowers researchers to perform differential qualitative and quantitative proteome analysis and is particularly advantageous for characterizing protein isoforms and post translationally modified proteins . Despite its popularity as the workhorse for proteomics in the past few decades it has been gradually displaced by the more sophisticated and high performance mass spectrometry based methods . However there are several variations of the 2 DE technique that have emerged as promising approaches that shine new light on specific niches that 2 DE could still contribute . In this review we first provide an overview of the applications of 2 DE its merits and pitfalls in the current proteomic research arena followed by a discussion on several alternative approaches for potential future applications .
|
Review of current trends of 2 DE applications in the field of proteomics. Strengths and shortcomings of 2 DE technique. Innovative adaptations of 2 DE for alternative applications and future prospects.
|
S0021967319312130
|
Recent studies have demonstrated that box shaped or cuboid packed bed chromatographic devices represent an efficient alternative to conventional cylindrical columns for high resolution preparative protein separations . This has been attributed to the greater uniformity of flow within these devices . However for a more complete explanation it is important to understand how the system hydrodynamics affects band broadening during the transport of proteins through these devices . In this study we present first principle mathematical models to capture this interplay . These models were validated by flow through and bind and elute experiments carried out using a colored protein as tracer . Control experiments were also carried out using equivalent commercial columns i.e . having same bed height and cross sectional area and packed with same media . The trends observed in the experiments matched those predicted by the models though there were deviations in the absolute values . These deviations are explained in terms of non idealities that exist in the experimental set up as well as in terms of factors that were not considered in the model . The models discussed in this paper are not only useful for understanding the workings of the cuboid packed bed device but are also useful tools for designing optimizing and scaling up such devices .
|
First principle mathematical model for convective transport of protein bands. Study of interplay between system hydrodynamics and band broadening. Validation for model using colored protein solutions as tracer. Useful tools for designing optimizing and scaling up chromatography.
|
S0021967319312142
|
Potassium bromate is a food additive used as flour improver in the baking industry . Bromate is considered a carcinogenic and nephrotoxic substance . Thus the bromate concentration must be carefully monitored in flour products . We developed a method for a selective and sensitive determination of bromate in flour that uses ion chromatography coupled with single quadrupole mass spectrometry . A recently introduced high capacity anion exchange column was used to separate bromate from matrix anions . Six commercial flour and flour products including homemade bread baked using flour containing potassium bromate were analyzed . The method showed good precision with RSDs 0.2 and 5
|
A high capacity ion exchange column was used to separate bromate from matrix anions. The MS provided high specificity for samples with an unresolved bromate peak. Bread baked using 65mg Kg KBrO. showed 60g kg residual bromate after baking. Method showed good accuracy with recovery of 86110 for bromate in the samples.
|
S0021967319312166
|
Advanced glycation end products and protein cross links have been extensively investigated in both food and biomedical fields over the past years . Although there are a few chromatographic and immunological methods for the analysis of selected AGEs there is no method available for comprehensive simultaneous analysis of major AGEs found in processed foods and biological samples . In the present study we have reported a validated UHPLC MS MS method for simultaneous identification and quantification of 15 different AGEs furosine 2 protein derived cross links and 2 amino acids . The analytes were separated on a reversed phase C 18 column and quantified accurately based on the isotope dilution method where 9 stable isotope labelled internal standards were used to quantify 20 different analytes using an Orbitrap mass analyzer . The method showed acceptable linearity accuracy and precision . The LOD and LOQ values in plasma were in the range of 0.3019.02 and 0.8757.06ng mL respectively . The recovery values at the three spiked levels were in the range of 71110 with some exceptions . The intraday and interday precision were in the range of 1.513.2 however quantification of N lysine accompanied slightly higher interday precision . The applicability of the method was successfully assessed by analyzing AGEs and protein cross links in six different complex matrices including Ultra High Temperature processed milk roasted chicken breast meat roasted chicken skin roasted pork liver bovine plasma and perfusion liquid .
|
Simultaneous analysis of 15 different advanced glycation end products. Furosine an early stage Maillard reaction marker is included in the method. Protein derived cross links lysinoalanine and lanthionine can be quantified. Validation revealed acceptable accuracy and precision. Method was successfully applied to 6 different food and biological matrices.
|
S0021967319312178
|
An original multiresidue method based on thermal extraction and gas chromatography tandem mass spectrometry was developed to simultaneously quantify from a very small amount of sample a wide range of concerning SVOCs including polycyclic musks organochlorines organophosphates oxadiazolones polycyclic aromatic hydrocarbons polybromodiphenylethers polychlorobiphenyls phthalates and pyrethroids in indoor settled dust . Method limits of quantification ranged from 5ng g
|
Simultaneous analysis of 44 SVOCs of health concern in indoor settled dust. Simple cost effective and environmentally friendly method based on thermal extraction. Precise and accurate quantification of a wide range of SVOCs from only 2mg of sieved dust. Suitable method for environmental monitoring programs or large scale studies.
|
S0021967319312208
|
Amino acids are most often analyzed in reversed phase liquid chromatography after a derivatization procedure to render them sufficiently hydrophobic and detectable with UV or fluorimetric detection . Simpler methods should be possible to avoid additional chemical reactions . We present an improved method to analyze free amino acids with unified chromatography that is to say with a wide elution gradient starting with supercritical fluid chromatography conditions and ending with high performance liquid chromatography conditions . The mobile phase composition was carefully adjusted to permit the elution of 21 natural amino acids with very good peak shapes from a zwitterionic cinchona based stationary phase . Chiral separation was not desired . The mobile phase finally selected comprised carbon dioxide and a co solvent ranging from 10 to 100 in 7min followed by 3min re equilibration at 25C . A reversed pressure gradient and a reversed flow rate gradient were applied to avoid reaching the upper pressure limit of the pumping system and to favor high chromatographic efficiency at every stage of the elution gradient . Detection was achieved with electrospray ionization mass spectrometry MS . The method is then fast and straightforward as no derivatization step is necessary and all isobaric species were chromatographically resolved .
|
Free amino acids analyzed in unified chromatography from SFC to HPLC. Adapted operating conditions to optimize run time and efficiency. Separation of isobaric isomers of leucine and isoleucine. Quantification with ESI MS detection in dietary supplements.
|
S002196731931221X
|
Perfluorinated compounds are new types of persistent organic pollutants known to bioaccumulate in organism which have come under increased scrutiny due to the close relation with various health problems . Sensitive detection of PFCs remains a significant challenge because of their ultratrace levels in complex samples . Herein fluorinated magnetic covalent organic frameworks Fe
|
Fluorinated magnetic COFs were synthesized via in situ growth strategy. The magnetic COFs exhibited high adsorption performance towards six PFCs. The FM SPE HPLC MS MS method was simple fast highly efficient and selective. The developed method can be applied for the detection of ultratrace PFCs in milk.
|
S0021967319312233
|
The international trade in illegally logged and environmentally endangered timber has spurred enforcement agencies to seek additional technical procedures for the identification of wood species . All
|
Timber extracts exploited using GC QToF for chemotyping forensic analysis. Differentiation and determination of wood achieved at genus species level. CITES listed wood species investigated and identified with the new method. EI wood spectral library suitable for method transfer to routine environmental labs.
|
S0021967319312245
|
Inspired by the fact that antibody recognizes antigen s epitope rather than its whole structure we selected the glycosyl moiety of teicoplanin as the template 4 vinylphenylboronic acid and methyl methacrylate as the functional monomers and divinylbenzene as the cross linker to synthesis molecularly imprinted polymer microspheres
|
The glycosyl moiety of teicoplanin was used as a template for boronate affinity molecular imprinting. The MIPs showed pH controlled catch and release recognition mechanism. Highly sensitive detection of five teicoplanin components was achieved with an instrumental analysis time of 4min.
|
S0021967319312257
|
In this present work a novel polyaniline functionalized melamine sponge was successfully prepared using a simple unstirred in situ polymerization process . The PMs was characterized using a scanning electron microscope and contact angle measurements . Its adsorption performance was initially determined via dye adsorption assays and the conditions affecting the synthesis including polymerization time acidity molar ratio and number and sizes of raw melamine sponge were optimized . The PMs was then used as an efficient adsorbent for the development of a novel low cost method for the detection of two representative perfluorinated chemicals perfluorooctanoic acid and perfluorooctane sulfonate using ultra performance liquid chromatography triple quadrupole mass spectrometry with the internal standard method . To achieve the best extraction efficiency with this method several variables were optimized including adsorption time pH value the number of PMs and desorption conditions . Calibration graphs showed a good linear degree at concentration ranging from 0.1 to 50gL
|
A novel kind of polyaniline functionalized melamine sponge PMs was prepared. PMs was used for extraction of two representative perfluorinated chemicals PFCs . The proposed method was used to measure PFC concentrations in biological samples.
|
S0021967319312269
|
Sealants incorporated in the lids of food cans to ensure the can is hermetically sealed are formulated from a wide variety of compounds . These compounds and associated non intentionally added substances could migrate to the food contained in the can . In this work ion mobility quadrupole time of flight mass spectrometry coupled to ultra high performance liquid chromatography has been used to obtain ion mobility filtered extracted ion chromatograms . Subsequently accurate mass precursor ions and their fragments have been used to identify the compounds migrating from the sealant to the content of the cans . Moreover the correlation between the collision cross section values and
|
UHPLC IM QTOF MS used to obtain ion mobility filtered extracted ion chromatograms. Accurate mass precursor ions and their product ions used for identification of food migrants. Migrants come from sealants used in food cans. Seven migrants were found in the food simulants. Five non intentionally added substances NIAS were detected.
|
S0021967319312270
|
Natural products including alkaloids are important resources for new drugs . However in today s high throughput screening environment natural product drug discovery programs are challenged for their low efficiency . In order to adapt to current HTS models we here developed a rapid sample saving and miniaturized paradigm that seamlessly integrated alkaloid micro fractionation quantitative analysis qualitative analysis and phenotypic screening . In the work alkaloid samples were analyzed and fractionated on an analytical charged C18 column and fraction qualities were determined by a charged aerosol detector . Fraction activities on dopamine D2 receptor were screened by cellular dynamic mass redistribution assay and active fractions were further characterized by high resolution mass spectrometry . The whole workflow was first validated by mixed standard for accuracy and then by 300 g of
|
Integrated method accelerated alkaloid drug discovery. XCharge C18 column provided good peak shape for alkaloids. Charged aerosol detector CAD ensured accurate screening of trace samples. Molecular network predicted active compounds.
|
S0021967319312282
|
The aim of this study was to estimate the retention time variability under reproducible conditions of an SFC MS analytical method for routine anti doping analyses . For this purpose a set of 51 doping agents as neat standards and spiked in diluted urine was used to assess their retention times variability over a period of four months as well as the column
|
Evaluation of retention times variability in SFC MS in neat standards and urine. Three UHPSFC stationary phases were tested under a period of four months. RSD values 1.5 were obtained on two UHPSFC stationary phases after four months. Column inter batch variability was also excellent RSD 2 .
|
S0021967319312294
|
A facile strategy for highly efficient fabrication of chiral monolithic column was carried out by the simple one pot hydroxymethyl polycondensation of native cyclodextrin and urea formaldehyde . In situ rapid substitution of native CD and efficient polycondensation of CD products and UF oligomers was proposed and fulfilled in one pot . The feasibility mechanism and key parameters of polycondensation reaction were discussed . The data on crosslinking polycondensation and reaction kinetics were further evaluated . Characteristics including the morphologies permeability and structure stability of the resultant monolithic columns were also studied . Under the optimal conditions the one pot hydroxymethyl polycondensation was accomplished in an aqueous solution within only 10 mins . Satisfactory stability and repeatability were gained and good enantioseparation of eight model enantiomers was successfully achieved with the resultant CD based monolith . It was simple and highly efficient and the organic solvents special CD derivatives and tediously long time polymerization reaction were successfully avoided which might light a new access to rapid preparation of CD chiral monolith for high performance enantioseparation .
|
Hydroxymethyl polycondensation of native CD and UF was firstly exploited. Rapid fabrication of CD chiral monolith was fulfilled in 10 mins. It was simple and free of special CD derivatives or organic solvents. Satisfactory stability and acceptable repeatability were exhibited. High performance separation for polar enantiomers was achieved in CLC.
|
S0021967319312312
|
Royal Jelly constitutes one of the most popular beehive products and for this reason the use of inexpensive sweeteners during its production remains an important quality issue . In the present study we report results of metabolic profiling of RJ samples obtained after the application of artificial bee feeding using different feeding protocols . The hydrophilic content of RJ samples was assessed by applying UPLC MS MS . In total 96 crude RJ samples were analysed with the developed method . Multivariate statistical analysis revealed clear differentiation between the RJ samples obtained from control bees and samples obtained after feeding . In total 27 out of 57 detected molecules were statistically found to be significantly altered in the different comparisons . Among them some amino acids amino acid derivatives amines carbohydrates and vitamins were found as potential markers . The results of the study could be further used for the development of an LC MS based analytical tool for RJ quality control assessment .
|
Hydrophilic metabolic profiling of royal jelly samples. Assessment of the authenticity of royal jelly production. Detection of markers for royal jelly quality control. Alteration of royal jelly s metabolic profile from bees under sugar feeding.
|
S0021967319312324
|
Micellar liquid chromatography is a reversed phase mode with mobile phases containing an organic solvent and a micellised surfactant . Most procedures developed in MLC are implemented in the isocratic mode since the general elution problem in chromatography is less troublesome . However gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities in shorter times . MLC using gradients is attractive to determine by direct injection moderate to low polar compounds in physiological samples . In these analyses the use of initial micellar conditions with a fixed amount of surfactant above the critical micellar concentration keeping the organic solvent content low will provide better protection of the column against the precipitation of the proteins in the physiological fluid . Once the proteins are swept away the elution strength can be increased using a positive gradient of organic solvent to reduce the analysis time . This may give rise to the transition from the micellar to the submicellar mode since micelles are destroyed at sufficiently high concentration of organic solvent . In this work several retention models covering extended solvent domains in MLC are developed and tested and applied to investigate the performance in isocratic linear and multi linear gradient separations . The study was applied to the screening of adrenoceptor antagonists in urine samples using mobile phases prepared with sodium dodecyl sulphate and 1 propanol . Predicted chromatograms were highly accurate in all situations although suffered of baseline problems and minor shifts for peaks eluting close to a steep gradient segment . Two columns were investigated with the C8 column being preferable owing to the smaller amount of adsorbed surfactant .
|
Screening of drugs in urine samples with direct injection is carried out. Retention models are developed for micellar eluents with extended solvent domains. Isocratic linear and multi linear separations are interpretively optimised. Consequences of surfactant desorption in C8 and C18 columns by a gradient are shown. Excellent agreement between predictions and experimental chromatograms is found.
|
S0021967319312348
|
The liquid crystal state is an ordered physical state between a solid and a liquid . Previous research in gas chromatography proved that it provides a geometric selectivity which allows the separation of geometric position isomers and
|
BHOBP is the first liquid crystal stationary phase for GC bearing a bromine atom. The supercooled liquid crystal state was stable over several weeks. BHOBP improved the shape selectivity of low boiling organic compounds. An original selectivity for geometric isomers was obtained.
|
S002196731931235X
|
Automatic data analysis for gas chromatography mass spectrometry is a challenging task in untargeted metabolomics . In this work we provide a novel comprehensive data analysis strategy for GC MS based untargeted metabolomics by developing a new automatic strategy for performing TIC peak detection and resolution and proposing a novel time shift correction and component registration algorithm . autoGCMSDataAnal uses original acquired GC MS datafiles as input to automatically perform TIC peak detection component resolution time shift correction and component registration statistical analysis and compound identification . We utilize standards and complex plant samples to comprehensively investigate the performance of autoGCMSDataAnal . The results suggest that the developed strategy is comparable with several state of the art methods that are widely used in GC MS based untargeted metabolomics . Based on the proposed strategy we develop a user friendly MATLAB GUI for users who are unfamiliar with programming languages to facilitate their routine analysis which can be freely downloaded at
|
We propose a comprehensive data analysis workflow for GC MS based metabolomics. An automatic TIC peak detection and resolution methodology is proposed. A new time shift correction and component registration algorithm is developed. A MATLAB GUI is developed based on the developed strategy for users.
|
S0021967319312361
|
The halogen bond is a noncovalent interaction involving a halogen acting as electrophile and a Lewis base . In the last decades XB has found practical application in several fields . Nevertheless despite the pivotal role of noncovalent interactions in separation science investigations of XB in this field are still in their infancy and so far a limited number of studies focusing on solid phase extraction liquid liquid microextraction liquid phase chromatography and gas chromatography separation have been published . In addition in the last few years our groups have been systematically studying the potentiality of XB for HPLC enantioseparations . On this basis in the present paper up to date results emerging from focused experiments and theoretical analyses performed by our laboratories are integrated with a descriptive presentation of XB features and the few studies published until now in separation science . Then the aim of this article is to provide a comprehensive and critical discussion of the topic and account for some still open issues in the application of XB to separate chemical mixtures .
|
Critical analysis of halogen bond XB function in separation science. Applications of XB in separations science. Theoretical methods to study XB in separation science. Open issues and perspectives in the study of XB in enantioseparation science.
|
S0021967319312373
|
The thermodynamic behavior of octreotide a cyclic octapeptide with important pharmaceutical functions has been simulated under reversed phase gradient elution conditions . To this end adsorption behavior was firstly investigated in isocratic conditions under a variety of water acetonitrile 0.02 trifluoroacetic acid mixtures as mobile phase by using a Langmuir isotherm . Organic modifier was varied in the range between 23 and 28 . Adsorption isotherms were determined by means of the so called Inverse Method with a minimum amount of peptide . The linear solvent strength model was used to find the correlation between isotherm parameters and mobile phase composition . This study contributes to enlarge our knowledge on the chromatographic behavior under nonlinear gradient conditions of peptides . In particular it focuses on a cyclic octapeptide .
|
Adsorption behavior of octreotide has been modeled in gradient elution RP LC. Inverse Method allows to get fundamental information by using only a few milligrams. Study of thermodynamics is necessary for the optimization of continuous separations. This approach can be adopted when a reduced amount of peptide is available.
|
S0021967319312385
|
Biological samples are usually complex matrices due to the presence of proteins salts and a variety of organic compounds with chemical properties similar to those of the target analytes . Therefore sample preparation is often mandatory in order to isolate the analytes from troublesome matrices before instrumental analysis . Because the number of samples in drug development doping analysis forensic science toxicological analysis and preclinical and clinical assays is steadily increasing novel high throughput sample preparation approaches are calling for . The key factors in this development are the miniaturization and the automation of the sample preparation approaches so as to cope with most of the twelve principles of green chemistry . In this review recent trends in sample preparation and novel strategies will be discussed in detail with particular focus on sorptive and liquid phase microextraction in bioanalysis . The actual applicability of selective sorbents is also considered . Additionally the role of 3D printing in microextraction for bioanalytical methods will be pinpointed .
|
MIPs and graphene tablets for drug extraction from biological fluids. Microextraction by packed sorbent for bioanalytical applications. Liquid phase microextraction based on supported liquid membranes compatible with biological fluids. High performance materials as extractant phases. 3D printing in microextraction for bioanalytical applications.
|
S0021967319312397
|
Microporous organic network is a promise class of functional materials in solid phase extraction . However the previous MON based SPE works are all focused on off line mode . The inherent drawbacks of off line SPE such as complicated operation steps and poor repeatability still hinder the potential applications of MON . In addition direct use of traditional synthesized nano sized MON in on line SPE is impractical . To solve these issues here we show the synthesis of silica amino functionalized MON SiO
|
SiO. @MON NH. microsphere was fabricated for on line SPE. The developed on line SPE HPLC method gave wide linear range low LODs and large EFs for phenols. Hydrogen bonding and hydrophobic interaction dominant the good extraction.
|
S0021967319312403
|
Polyglycerol esters produced by esterification of fatty acids on polyglycerols were analysed by High Resolution Mass Spectrometry HPLC MS and U HPLC MS. A structural study of PGEs in 4 samples synthesised by the Gattefoss company was carried out using an elemental analysis of HRMS spectra and modelling of all probable isomers and cyclic structures . The results were used to construct a structural database of all species present in the 4 samples . After an assessment of the selectivity of 5 reversed phase columns Aeris Widepore XB C8 3.6m 2.1150mm Acquity CSH C18 1.7m 2.150mm Acquity CSH Phenyl Hexyl 1.7m 2.150mm Acquity CSH Fluoro Phenyl 1.7m 2.150mm and Kinetex F5 1.7m 2.1100mm HPLC MS and U HPLC MS analyses were performed on an Aeris Widepore XB C8 column and Acquity CSH Fluoro Phenyl column with aqueous formic acid acetonitrile in gradient mode . The separation was optimised with 10min and 5min of gradient . The detection performed on a QDA detector produced extracted ion chromatograms based on all adducts identified in the HRMS analysis . HPLC and U HPLC analyses showed the different mono and di ester species and provided relative quantification of all identified constituents . The combined analyses of the HRMS HPLC MS and U HPLC MS results were used to compare the different PGE batches and quantify the molecular constituents according to their relative abundance for these complex mixtures . With HPLC and U HPLC analyses using 2 different gradient times and 2 different selectivity columns and comparing the retention factors and log P of the different species it was possible to link structural identification and relative quantification of all PGEs identified in the samples .
|
Batch comparisons and quantification of constituents of complex formulations. Structural database construction with HRMS spectra and modelling of all probable PGEs. HRMS and U HPLC MS can link structural identification to relative PGEs quantification.
|
S0021967319312415
|
With 4 4 diaminoterphenyl and phloroglucinol as the monomers Azo linked porous organic polymer was prepared by a green mild azo reaction . Azo PP is rich in phenolic hydroxyl groups and benzene rings which can form intermolecular hydrogen bonds with the phenolic hydroxyl groups in interest benzotriazoles . The interaction between the benzene ring and the triazole ring would promote the adsorption of target BZTs on Azo PP . Azo PP polydimethylsiloxane coated stir bar was prepared via sol gel technique for the extraction of target BZTs . Compared with commercial stir bar Azo PP coated stir bar showed superior extraction efficiency under similar conditions and kinetics . A method of stir bar sorptive extraction combined with high performance liquid chromatography diode array detector was developed to analyze six target BZT UltraViolet absorbers . The optimization of SBSE conditions for extraction of interest BZTs was performed by single factor test . Under the optimized conditions the limits of detection within 0.120.33g L were achieved for six BZT UV absorbers with the linear range within 0.5100g L. The method was applied to detect six BZT UV absorbers in the East Lake water Yangtze River water and campus soil samples . No BZT was detected in any of the samples . The recoveries of target BZTs in spiked samples were found in the range of 94.9118 96.2118 and 88.2119 .
|
Azo linked porous organic polymer PP was synthesized by a mild azo reaction in water. Azo PP coated stir bar was prepared for extraction of six benzotriazoles BZTs . The azo PP coated stir bar showed superior extraction efficiency and kinetics over commercial PDMS stir bar. The method is simple faster than other SBSE methods and sensitive for trace BZTs analysis.
|
S0021967319312427
|
This work proposed a novel strategy based on quadruplex stable isotope derivatization for sensitive accurate speedy and green determination of panaxadiol and panaxatriol . This strategy integrated with ultrasound assisted dispersive liquid liquid microextraction microwave assisted derivatization and magnetic graphene oxide dispersive solid phase extraction as efficient sample pretreatment techniques coupling with ultra high performance liquid chromatography tandem mass spectrometry detection in multiple reaction monitoring mode for the analytical purpose of high throughput sensitivity selectivity green and accuracy . Quadruplex mass spectrometry sensitizing derivatization reagents 3
|
New quadruplex derivatization reagents ACCR6G were designed and synthesized. Novel analytical method of DLLME QSID DSPE UHPLC MS MS was developed for PD and PT. The developed method was high throughput sensitive selective accurate and green. The method was applied to the quality control of foodstuff and medicinal materials.
|
S0021967319312439
|
Based on our previous work with pseudostationary ion exchanger sweeping we use this strategy to develop a sensitive reliable and robust method for the analysis of the newly FDA approved hepatitis C antiviral drugs namely sofosbuvir daclatasvir ledipasvir and velpatasvir in their pure forms and co formulated pharmaceutical dosage forms using micellar electrokinetic chromatography as a separation method . For the first time a successful separation of all the investigated compounds was achieved in less than 8min using a basic background electrolyte composed of 25mmol L
|
A robust MEKC method was developed for analysis of hepatitis C antivirals. Optimization of sample BGE composition was performed to solve adsorption problems. With focusing methods concentration sensitivity is significantly improved. Good validation data permit using the MEKC method in quality control laboratories. Approaches established can be used for analysis of other basic hydrophobic analytes.
|
S0021967319312713
|
We report on a direct comparison of the separation performance in capillary nano LC between commercial packed bed columns and the small domain silica monoliths in applications . Octadecylsilylated monolithic silica capillary columns with a 50 and 100 m inner diameter were prepared with a procedure providing domain sizes in the sub 2 m range . The fabricated monolith columns could provide plate heights
|
Monolithic silica columns with sub 2 m domain size have been synthesized. The produced monolith columns provide a high column efficiency. 4 m . Peak capacities. are 3040 higher than in a commercial particle column. A high repeatability of the performance of the fabricated columns is demonstrated.
|
S0021967319312725
|
The correct identification of the metalloproteins present in human tissues and fluids is essential to our understanding of the cellular mechanisms underpinning a host of health disorders . Separation and analysis of biological samples are typically done
|
NH. NO. Tris HCl and NH. CH. COO are optimal buffers for use in SEC ICP MS metalloprotein analyses. Optimal range of buffer concentration is 50200mM in SEC ICP MS. 100mM concentration reduces both protein column interactions and ICP MS maintenance. Dextran based columns are best suited for the analysis of apo copper proteins.
|
S0021967319312737
|
Click chemistry has attracted increasing attention for the synthesis of novel stationary phases . Considering the advantage of click chemistry a strategy based on thiol Michael addition was developed for the preparation of a new stationary phase herein and a phenyl vinyl sulfone stationary phase was prepared . The resulting M PVS bonded silica was characterized by elemental analysis solid state
|
It is the first time that thiol Michael addition reaction was used for chemical modification on silica particle herein. A new phenyl vinyl sulfone stationary phase was synthesized and characterized. This stationary phase provided multiple interactions.
|
S0021967319312749
|
An ultra high performance liquid chromatography tandem mass spectrometry method based on selective accelerated solvent extraction and magnetic material purification was established to analyze the residues of various veterinary antibiotics and agricultural fungicides and insecticides in livestock and poultry excrement . Methanolacetonitrile was used as the extraction solvent and static extraction was conducted three times in 5 min . Preliminary purification was achieved by adding 0.5g acidic aluminaflorisil to the extraction cell while the extraction was conducted . This preliminarily purified extract was further purified using magnetic material then analyzed using UPLCMS MS . Under optimal conditions 33 types of antibiotics including 3 amphenicols 8 macrolides 17 sulfonamides and 5 nitroimidazoles as well as 37 types of pesticides including 27 insecticides and 10 fungicides were detected . Recoveries ranged from 60.3 to 110.0 at three spiked concentrations the detection limits ranged from 0.2 to 3.5g kg and the quantitative limits ranged from 0.5 to 11.5g kg . This newly established method was tested using 30 livestock and poultry excrement samples and confirmed its use for determining veterinary drugs and pesticides in practical samples .
|
Simultaneously detecting 33 antibiotics and 37 pesticides in animal excrement. Selective accelerated solvent extraction plus magnetic material purification. Acceptable method accuracy and sensitivity for real samples detection.
|
S0021967319312907
|
Polymers obtained from tetraethyl orthosilicate and triethoxymethylsilane have been functionalized with different metal and metal oxide nanoparticles and used as coatings of extractive capillaries for the extraction of polar compounds by in tube solid phase microextraction coupled on line to nano liquid chromatography . The extraction capabilities of the new phases have been studied using several triazinic herbicides with log of octanol water partition coefficients K
|
Polymers with different metal and metal oxide nanoparticles have been synthetized. They have been used for in tube solid phase microextraction nano chromatography. The new sorbents can be used for herbicides with broad polarities and amino acids. Best results for the most polar compounds were obtained with CuO nanoparticles. The new phase is compatible with reversed phase and HILIC separations.
|
S0021967319312919
|
The method development of liquid liquid chromatography either countercurrent chromatography or centrifugal partition chromatography is slowed down by the selection of the biphasic solvent system that constitutes its column . This paper introduces a classification of 19 solvent systems including the most popular systems based on heptane ethyl acetate methanol water some non aqueous systems and some greener systems . This classification is based on Abraham descriptors determined through the partition coefficients of 43 probes . Among 21 determined models nine of them allow an accurate prediction of partition coefficients from solute descriptors and another ten provide a description of the chromatographic interactions at the 5 significance level . A graphical tool is built for the comparison of the chromatographic columns previously characterized with the solvation parameter model . The position of a solvent system in this spider diagram relates to the interactions at stake thus the selection of columns offering similar or orthogonal interactions is facilitated with no previous knowledge of the solute required . This semi empirical strategy can not fully predict the retention behavior but can judiciously orientate the user towards a limited number of solvent systems to be experimentally tested .
|
Determination of Abraham parameters for 21 biphasic solvent systems. Use of a spider diagram for the classification of countercurrent centrifugal partition chromatography columns. Selection of orthogonal columns is facilitated.
|
S0021967319312932
|
Fast active sampling of volatile organic compounds under field conditions still is a great challenge especially when the exposure time to the source of emissions is a restricting factor . Hence to identify ideal conditions for such applications we systematically compared
|
With. VOCs are better recovered with XAD 2 than with Tenax TA. The recovery of VOCs decreases with high sample flow rates. In general XAD 2 is the better option for sampling of VVOCs than Tenax TA.
|
S0021967319312944
|
A complete package of functions in the R language has been written for professional separation optimization of complex mixtures of ionized and or non ionized solutes . The package includes functions for base line correction of experimentally recorded chromatograms modeling of chromatographic peak shapes and retention data prediction of the retention time of the test analytes and or their chromatograms and separation optimization under either isocratic or single and or double gradient elution conditions by changing the organic modifier content and or eluent pH . The optimization functions presented in this study offer two different modes for selection of optimal separation conditions automatic and manual mode . In the automatic mode the optimal separation conditions are determined by maximizing the resolution within separation time preset by the analyst . In the manual mode the optimal separation conditions are selected via scatter or contour plots . The foreknowledge of the precise dependence of resolution and separation time upon one or two retention parameters of interest provided by the proposed computer assisted separation optimization method gives chromatographers a feel of confidence for the selection of the optimal conditions for a desired separation . An illustrative video given in the Supplementary material may encourage a novice practitioner in R programming language to follow the proposed separation optimization procedure in a real HPLC analysis .
|
Separation optimization in HPLC analysis is implemented in R programming language. Two different modes automatic and manual are offered for selection of optimal separation conditions. The R software is validated in separation optimization under isocratic monolinear and or bilinear conditions governed by variations of and or pH. The proposed R software is expected to be a valuable tool for simulating and optimizing separation conditions for ionizable and neutral compounds.
|
S0021967319312956
|
A tailor made porous molecularly imprinted polymer thin film was prepared by in situ photo radical polymerization on a glass slide and used as a microextraction adsorbent . Detection was carried out using gas chromatography mass spectrometry to afford a method suitable for the selective determination of trace concentrations of polycyclic aromatic sulfur heterocycles in seawater . PASHs are one of the most problematic aromatic organic pollutants as they are considered more persistent and toxic compared to other analogous aromatic compounds in the environment . The optimized thin film consisted of a 2 thiophenecarboxaldehyde pseudo template with 1 vinylimidazole as the functional monomer bisphenol A dimethacrylate as the cross linker acetonitrile as the porogen and polyethylene glycol to boost porosity through formation of interpenetrating polymer networks . The adsorption behaviours of the thin film including adsorption kinetics binding isotherms and selectivity of MIP thin film were investigated in detail . The highest imprinting factors and adsorption capacity for targeted PASHs were achieved at a template monomer cross linker ratio of 1 4 8 . The method with no sample or film pretreatment showed very good reproducibility for the extraction of PASHs from spiked seawater samples RSDs6.0
|
A procedure to prepare molecularly imprinted polymer thin film MIP thin film on a glass slide is proposed. Role and effect of various porogens on thin film formation was investigated and studied. The porosity of thin film was improved by adopting the principle of interpenetrating polymer networks IPNs . Analysis of seawater carried out without pre treatment using PASHs MIP thin films with GCMS. The size and shape of MIP slides and the ease of preparation makes them efficient for off site and on site environmental analysis when combined with a suitable detection system.
|
S0021967319312968
|
Several calibration approaches were evaluated for the quantitation of volatile organic compounds in air using miniaturized exhaustive and non exhaustive sampling techniques such as in tube extraction and solid phase microextraction Arrow . Eleven compounds 2 ethyl hexanol hexanal nonanal toluene ethyl benzene methyl isobutyl ketone acetophenone p cymene pinene trimethylamine and triethylamine all them found in the natural air samples were selected as model analytes . Liquid injection liquid standard addition to the sorbent bed and gas phase standards provided by an automatic permeation system were evaluated in the case of ITEX packed with laboratory made 10 polyacrylonitrile material . Two different approaches based on sampling of gas phase compounds from the permeation system and from sample vial containing gas phase standards were evaluated for SPME Arrow with two different coatings commercial divinylbenzene poly and laboratory made mesoporous Mobil Composition of Matter No . 41 . In addition interface model approach was used for the calculation of the real concentration of the target analytes in the sample from the total amount of analytes injected into the GCMS in the case of SPME Arrow . Similar results were obtained with the different approaches used for the quantitation by ITEX and SPME Arrow . However the use of gas phase standards with sample matrix similar to the natural samples allowed the permeation system to provide the most reliable results for the quantitation of the target analytes . For this approach linearity expressed as r
|
Different calibration approaches were evaluated for ITEX and SPME Arrow air sampling techniques. Permeation system provided accurate and reliable calibration curves for quantitation. Permeation system and liquid injection gave similar results with ITEX sampling. Interface model approach simplified the calculation of concentration in the air samples.
|
S002196731931297X
|
Drug containing nanoparticles are ideal targeted drug delivery systems . However methods for the simultaneous analysis of the drug within the nanoparticle and free drug in a short time are rather limited . In this study we developed a polymer modified monolithic column with cationic groups for the simultaneous analysis of the drug within the nanoparticle and the free drug . The use of the acrylamide group was determined as the optimum connecting group and the optimum concentration of the modifier was 6 . The prepared column retained the drug within the nanoparticle by anion exchange and its elution time was controlled by the ionic concentration aminomethane Tris of the mobile phase . The separation of two typical nanomedicines was studied on the prepared column . For DOXIL and Abraxane the drugs within the nanoparticle were well separated from the free drugs on the developed column . The developed polymer coated monolithic column with trimethylammonium modification is expected to enable the rapid analysis of various nanomedicines .
|
Simultaneous analysis of nanomedicine and free drug achieved. Monolithic column with cationic groups employed. 6 3 Acrylamidopropyl trimethylammonium chloride optimal for modification. Elution time of nanomedicines controlled by mobile phase ionic concentration.
|
S0021967319312981
|
Co occurrences of peptides and chemical components are usually observed in complicated matrices . Notably those traditional Chinese medicine prescriptions contain both plant and animal ingredients . It is still challenging to simultaneously monitor peptides and chemical components attributing to their different liquid chromatographic and mass spectrometric behaviors . Herein efforts were made to pursue an eligible approach enabling simultaneous determination of peptides and chemical components in a TCMP namely
|
RPLC HILICSRM was developed for simultaneously monitoring peptides and compounds. Online energy resolved mass spectrometry was developed for parameter optimization of peptides. RPLC and HILIC were serially coupled to retain and separate both peptides andcompounds. Mild inter batch variations were observed among different batches of CCPI.
|
S0021967319312993
|
In this study a heart cutting 2D LC method was successfully developed and optimized in order to discriminate and quantitate propranolol propranolol and its hydroxy metabolites namely the isomeric 4hydroxypropranolol 4hydroxypropranolol 5hydroxypropranolol 5hydroxypropranolol 7 hydroxypropranolol and 7hydroxypropranolol in one chromatographic run . Thereby experiments investigating chiral discrimination in ring hydroxylation of propranolol were made feasible .
|
Utilization of 2DLC QQQ MS MS allowed trace level determination suitable for bioanalysis. Achiral and chiral separation of propranolol and its ring hydroxylated metabolites. and. studies of metabolism of pharmaceutical propranolol. Chiral shift during enzymatic conversion to propranolol metabolites.
|
S0021967319313007
|
In this study a new automated magnetic micro solid phase extraction was introduced . A Tygon tube was folded and fixed around the pole of a cylindrical magnet . Nanosized magnetic sorbents modified with diphenyldichlorosilane were uniformly immobilized on one side of the inner wall of the tube . Sample solution and desorption solvent were passed through the tube using a peristaltic pump . Four phenylurea herbicides were used as the model compounds to evaluate the method performance . HPLC UV was used to separate and quantify the analytes . The effective parameters influencing the performance of the extraction process were investigated . The limit of detection was 0.04g
|
A new automated MSPE method was introduced. Sorbent was placed inside of a tube located near the pole of a cylindrical magnet. No frit was used for immobilization of sorbent inside of the extraction tube. The MSPE method was applied for the determination of phenylurea herbicides. The method was applicable for environmental water samples analysis.
|
S0021967319313019
|
There is an urgent need for the development of efficient and comprehensive analytical methods for organic chemical compounds due to their increasing number and diversity in children s toy products . The presence of these chemicals in toys poses an extreme risk for the health and development of children . In this study an analytical methodology has been developed using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry . This hybrid instrumentation together with an in house accurate mass database and a mass spectral library allows for wide scope screening and identification of hazardous substances in plastic toys . A total number of 200 compounds belonging to eight chemical families were investigated such as coloring agents plasticizers fragrance allergens nitrosamines primary aromatic amines flame retardants perfluorinated compounds and endocrine disruptors . Following a straightforward and efficient dissolution precipitation method for sample preparation chemical screening and confirmation were conducted by comparing the experimentally measured exact mass retention time and isotopic pattern with the accurate mass database and by matching the acquired MS MS spectra against the mass spectral library . The matrix effect linearity sensitivity precision and recovery of the proposed method were properly evaluated . The obtained limits of detection and quantitation were in the range of 0.010.98mgkg
|
UHPLC Q TOF MS for comprehensive screening of 200 hazardous substances in plastic toys. Custom built accurate mass database and mass spectral library for compound identification. The developed method was applied for the analysis of 55 real ABS and PVC toy samples.
|
S0021967319313020
|
This work proposes a novel Quick Easy Cheap Effective Rugged and Safe method in combination with ultra high performance liquid chromatography tandem mass spectrometry for the determination of sulfonylurea residues in edible seeds . The chromatographic separation of nine sulfonylureas was accomplished in less than 5.5min using a Luna Omega C
|
QuEChERS UHPLC MS MS for the analysis of nine sulfonylureas in edible seeds. Evaluation of different d SPE sorbents C18 PSA Z Sep. and EMR Lipids . Z Sep. provides high extraction efficiency for sulfonylureas in edible seeds. LOQs are lower than 1.64gkg. and reporting limits 5gkg. lower than MRLs. Precision and trueness fulfill the requirements of SANTE 11813 2017 guideline.
|
S0021967319313032
|
This paper demonstrated a simple and rapid approach for the determination of lead dioxide in minium using a headspace gas chromatographic technique . This new approach was based on the measurement of carbon dioxide from the redox reaction between lead dioxide and oxalic acid in a sealed headspace vial . The obtained results indicated that the new approach had good measurement accuracy and precision . Moreover the limit of quantification and limit of detection for this new approach were respectively 0.34 and 0.10 and the recoveries ranged from 97.9 to 101.7 . The new approach is low cost and reliable which has potential for use in the analysis of lead dioxide in minium and related products .
|
Efficient quantification of lead dioxide in minium. This method is based on the redox reaction of lead dioxide with oxalic acid. The CO. generated from the reaction can be analyzed by headapace GC. This method provides an alternative for the lead dioxide estimation in minium.
|
S0021967319313044
|
Distribution coefficient data provides the analyst with a powerful set of tools for designing elemental chemical separations . While considerable Kd data exists in the literature for traditional anion and cation exchange resins a comprehensive Kd study for the majority of the periodic table has not been published to date for several newer Eichrom extraction chromatographic resins . Kd values for the sorption of 41 different of elements on TEVA TRU UTEVA and Diphonix resin were determined in this work . The power of Kd data in designing chemical separations is then demonstrated through development of separation methods for several challenging chemical separations including U Mo Te Zr Nb Mo and Cd isolation . Separation methodologies are finally applied to soil samples where the ability for each separation to perform under complex matrix conditions is evaluated .
|
Kd data provides tool for designing new chemical separation methods. Kd data for 41 elements on TEVA TRU UTEVA Diphonix in HNO. and HCl are reported. Methodologies for U Mo Te Zr Nb Mo and Cd separations are demonstrated. Data provides foundation for designing future tunable elemental separations.
|
S0021967319313068
|
Although micellar electrokinetic chromatography mass spectrometry using bare silica capillary filled with molecular micelles is an advantageous hyphenated technique for chiral analysis it is still in the developmental stage . This is mainly because of the lower repeatability of retention time and peak area associated with the difficulty in controlling electroosmotic flow on bare silica capillaries . Besides the lower robustness and electrospray erosion of the fused silica capillary tip the lifetime is limited for 1015 runs per capillary column . We have tested a new MEKC MS method to eradicate this problem using a covalently bonded 2 acrylamido 2 methyl 1 propane sulfonic acid column filled with free floating molecular micelles polysodium
|
A combination of covalently bonded AMPS capillary column and molecular micelles. Optimize simultaneous chiral separations of three blockers. A simple precise and accurate MEKC MS MS for the quantitation of blockers in commercial tablets.
|
S002196731931307X
|
The elution behavior of bivalent bispecific antibodies comprising an immunoglobulin G framework genetically fused to a pair of single chain variable fragments was studied on hydrophobic interaction chromatography columns using ammonium sulfate gradients . Each of the BiSAb molecules studied exhibited a three peak elution behavior regardless of the location of scFv attachment to the framework IgG . Collecting and re injecting each of the isolated peaks and eluting with the same gradient resulted in the same three peak profile indicating that the behavior is reversible . Analogous behavior was observed for HIC resins with different functional ligands matrix structures and particle sizes . Residence time operating temperature and hold time were shown to affect the elution behavior . While three peaks were obtained at short residence times and room temperature residence times longer than about 27min or operating at 45C resulted in a single merged peak indicating that the underlying mechanism occurs on time scales comparable to that of chromatographic separation . Holding the protein on the resins prior to elution enriched the late eluting peak indicating that multiple binding states formed on the chromatographic surface are responsible for this behavior . Tryptophan auto fluorescence measurements show that stronger binding forms have increased solvent exposure indicating that surface catalyzed conformational changes play a role . A model was developed to describe the interplay of chromatographic separation and slow conformational changes .
|
Bispecific antibodies exhibit reversible three peak elution on HIC columns. Elution behavior caused by interconversion of three molecular forms. Phenomenological column model predicts gradient elution behavior. BiSAb multiple peak elution on HIC and CEX are compared.
|
S0021967319313081
|
Silica particles with various pore sizes were modified with poly via surface initiated atom transfer radical polymerization under different reaction conditions . Twenty different columns were prepared and characterized according to a test method for hydrophilic interaction chromatography columns . Hydrophilic retention by the SI ATRP columns was much higher than that of poly columns prepared via free radical polymerization and many commercially available HILIC columns . The SI ATRP columns displayed greater selectivity for OH groups than any of the HILIC columns based on their values . SI ATRP functionalization was used to increase the polymer chain density on the silica particles which suggested a brush type morphology and improved hydrophilic selectivity . This indicated that hydrophilic retention and selectivity could be controlled by adjusting the morphology of the organic stationary phase . This stationary phase design strategy was validated experimentally by the effective separation of highly hydrophilic analytes . The findings of this study will greatly contribute to the creation of better separation media .
|
20 Poly acrylamide type columns were synthesized by surface initiated ATRP. The new HILIC columns were characterized chromatographically. Density of polymer was different on each silica possessing 100 to 300 pores. Higher density of the polymer chain around. 5000 provided higher hydrophilicity. 200 Pore was found to be the best to prepare significantly hydrophilic columns.
|
S0021967319313093
|
The present paper builds upon previous work on mAb domain contributions to multimodal chromatography by examining how pH can impact mAb surface properties and retention in these systems . Linear salt gradient experiments were carried out between pH 57 for several mAbs with different pI and surface hydrophobicities in four different MM CEX resins at two ligand densities . mAb retention showed an inverse non linear correlation with pH . Changing pH affected the elution order creating unique windows of selectivity in each of the MM CEX resins . One mAb showed a pH dependent spectrum of domain contributions demonstrating that pH can be used to tune the relative importance of the
|
Evaluated mAb retention domain contributions and surface properties from pH 57. One mAb showed a pH dependent spectrum of domain contributions. pH can tune the relative importance of Fab vs. Fc binding sites for some mAbs. The titration of Histidine residues plays an important role in this pH range.
|
S002196731931310X
|
High pressure ion chromatography was coupled with sector field inductively coupled plasma mass spectrometry to separate plutonium uranium neodymium and gadolinium nuclides from isobaric nuclides and to quantify them with high sensitivity . In this study mixed bed ion exchange columns CG5A and CS5A were used from which Pu and U were eluted first using 1M nitric acid . The lanthanides were then separated using a gradient of 0.10.15M oxalic acid with the pH adjusted to 4.5 . The HPIC SF ICP MS method was validated using different sample matrices i.e . spent nuclear fuel and soil . The method was found to be repeatable and gave rise to transient signals suitable for quantification of nuclide specific concentrations using external calibration . In terms of accuracy the HPIC SF ICP MS measurement results were in good agreement with those obtained using thermal ionization mass spectrometry . Finally the method provides an improvement in sample throughput and reduces exposure of the operator to radiation compared to off line gravitational chromatography followed by TIMS .
|
Plutonium uranium and the lanthanides are separated in a single run using 1M nitric acid followed by a gradient of oxalic acid concentrations 0.10.15M at pH 4.5 on CG5A and CS5A mixed bed ion exchange columns in less than 60min. The HPIC SF ICP MS method offers time savings and reduces the radiation dose to the analyst compared to gravitational ion exchange chromatography requires weeks followed by TIMS for the analysis of spent nuclear fuel. The HPIC SF ICP MS method was found to result in linearly increasing pulse count signals over the range 110g.L. for Nd 10100g.L. for Gd 110g.L. for Pu and 0.524g.L. for U isotopes. Nuclide specific mass fractions derived from nuclide specific concentration measurements external calibration for Nd e.g. Nd. Nd and Gd isotopes e.g. Gd. Gd in a Gd spent nuclear fuel were 97103 and 90110 respectively of those obtained using TIMS. Concentrations of Pu and U determined using HPIC SF ICP MS were 105 and 97 respectively compared to their theoretical concentration in a. Pu spiked soil sample.
|
S0021967319313111
|
Sensitive methods are required for in situ monitoring of volatile organic compounds . Herein carbon nanotube sponges were investigated as a new type of adsorbent for enriching trace aromatic VOCs . A square pillar configuration of a CNT sponge was enclosed in a glass tube . After accumulating the sample vapor a direct current pulse through the CNT sponge allowed narrow desorption bandwidths of 0.480.84s and 1.2s and high desorption efficiency . Gas chromatographic analysis of a nine component VOC mixture gave enrichment factors of 88 to 323 toluene and
|
A porous carbon nanotube sponge was developed as a preconcentrator. The sponge showed a high adsorption capacity and rapid thermal desorption. Good enrichment enabled trace detection ppb of aromatic volatile organic compounds. Breakthrough curves for multicomponent mixtures showed displacement effects. Adsorption kinetic and isotherm models were fitted to the experimental data.
|
S0021967319313135
|
A deeper understanding of the nanoscale and mesoscale structure of chromatographic adsorbents and the distribution of proteins within the media is critical to a mechanistic understanding of separation processes using these materials . Characterisation of the media s architecture at this scale and protein adsorption within is challenging using conventional techniques . In this study we propose a novel resin characterisation technique that enables
|
Antibody structure is measured during purification protein A chromatography. 1mL flow cell enabled. measurement using Small Angle Neutron Scattering. Protein A chromatography resin and bound antibody studied at nano mesoscales. Buffer conditions alter the antibody structure in its adsorbed state.
|
S0021967319313147
|
A rapid separation and quantitation of the stereoisomer amino sugars glucosamine galactosamine and mannosamine along with muramic acid is needed . These compounds when their quantities are accurate can be used to understand the origin and fate of natural organic matter in the environment . These target molecules are biomarkers of fungi and bacteria and allow the deconvolution of microbial transformations and degradation of NOM in a wide variety of environmental matrices . Analytical methods applied to this suite of biomarkers are needed to understand carbon and nitrogen biogeochemistry with a changing global climate . Traditional separations of these analytes by gas chromatography require sample derivatization as does reverse phase liquid chromatography . In contrast ion chromatography can separate the analytes directly but requires a separate analytical method to quantify muramic acid . In this work we present a direct analysis of all these molecules using hydrophilic liquid interaction chromatography . Solvent composition buffer strength pH flow rate and column temperature were optimized . The method can separate these four compounds and the biopolymeric precursor molecule N acetylglucosamine in a single run in under 8min with equivalent resolution to the best previously reported separations that did not require derivatization prior to analysis . Detection of the analytes was performed by both tandem and time of flight mass spectrometry . The method was assessed for its quantitative capabilities through i peak area assignment ii check standards with ratios of the target analytes likely to be present in real samples iii an injection internal standard and iv quantitative analysis of real soil hydrolysates by external calibration and standard addition approaches . Across their expected analytical ranges the response for each analyte was highly linear with good accuracy and precision over three orders of magnitude . Detection limits of 20gL
|
Ten minute separation of amino sugars muramic acid and N acetyl glucosamine. Separation optimized for mobile phase pH buffer strength and temperature. Accuracy 25 and precision 15 at environmental levels and ratios. Detection limits of 20gL. for galactosamine and 5gL. for other analytes. Amino sugar soil hydrolysates quantified by external calibration and standard addition.
|
S0021967319313159
|
The aim of this study was to develop a statistical model based on a set of intuitive topological descriptors that will help to determine the influence of the polychlorinated biphenyls structural features on the chromatographic behavior of these analytes in a variety of gas chromatographic stationary phases including the highly polar ionic liquid based SLB IL76 and SLB IL60 columns . The model was developed using the stepwise multiple linear regression method and constructed through several levels of increasing complexity to make evident the relative influence of the selected descriptors .
|
A simple statistical model based on topological descriptors has been developed. The feasibility of the model was evaluated on six GC stationary phases. Evaluated phases covered a wide range of chemical structures and polarities. Appropriate prediction of the chromatographic behavior of PCBs was possible. Prediction of PCB behavior in IL based phases was reported for the first time.
|
S0021967319313160
|
Posaconazole represents a triazole antifungal agent which is used to treat various fungal infections . It contains four chiral centers leading to 16 stereoisomers . With the convergent synthesis route only 11 related stereoisomeric impurities may potentially exist in the active pharmaceutical ingredient . It is a challenge to separate all the stereoisomers in one run . To address this problem a multiple heart cutting chiralchiral two dimensional liquid chromatography method was developed . The multiple heart cutting 2D LC separation was implemented on 2D LC system with three chiral columns with immobilized polysaccharide chiral stationary phases namely Chiralpak IB IC and IF3 . In the system the column Chiralpak IB was used as the
|
2D LC method was developed for separating posaconazole related stereoisomers. Chiralchiral column configuration is necessary for the stereoisomer separation. The 1D effluent has no influence on the performance of 2D separation. 12 posaconazole related stereoisomers can be baseline separated in one run. The method can be used for separation of other chiral drug stereoisomers.
|
S0021967319313172
|
Protein purification processes in basic research using KTA liquid chromatography systems are often limited to single sample injections and simple one column purifications . Because many target proteins in structural biology require complex purification protocols the work easily becomes laborious . To streamline and accelerate downstream protein production an ALIAS
|
The most frequently used protein purification methods were automated on KTA system. ALIAS autosampler was implemented in purification workflow to increase throughput. Developed multi column schemes reduced human labor and performed precisely in repetitive experiments. Novel system configuration allows the indefinite cycling of column steps.
|
S0021967319313184
|
The functionalization of covalent organic frameworks enhances chemical properties and expands future applications . Herein a facile strategy for sulfoacid functionalized COF is presented through post modification of covalent triazine frameworks platform . The magnetic solid phase extraction material is obtained by anchoring in situ Ni particles on CTF support Ni CTF SO
|
Magnetic sulfoacid functionalized covalent triazine framework was prepared maintaining porosity and crystallinity. Benzene triazine and sulfoacid moieties afford dual retention mechanism of hydrophilic lipophilic balance and cation exchange. Enriching basic benzimidazoles from food samples and reducing matrix effect simultaneously are achieved. The developed method offers wide linear range good precision and low detection limit.
|
S0021967319313196
|
The need for the control of rodent populations with anticoagulant rodenticides remains actual and enantioselective analytical methods are mandatory to understand ecotoxicity issues of those chiral pesticides . This study presents two enantioselective methods to achieve the residue levels and differentiated persistence of the four stereoisomers of difethialone which is one of the most toxic second generation anticoagulant rodenticide . Their enantiomeric fraction evaluation in biological matrices of rats was determined by two LC MS MS methods . The first one combined a chiral column employed in reversed phase mode to be compatible with mass spectrometry detection . The second one was also a LC MS MS method but with a reversed phase column after a derivatization step with camphanic chloride . Extraction process combined Solid Liquid extraction and sorbent cartridges . The methods were fully validated . The chiral column was chosen as a reference method for our laboratory because it was quicker and cheaper and enantioresolution and sensitivity were better . This chiral LC MS MS method was used to measure the enantiomeric fraction of the four stereoisomers of difethialone in rodent biological matrices of female rats treated with 3.5mg kg of difethialone . The results showed that metabolism is not the same for all the stereoisomers cis E3 difethialone was the most persistent and E4 trans difethialone was the most quickly eliminated .
|
Second generation anticoagulant generation rodenticides are chiral pesticides. Residue levels of the four stereoisomers of difethialone were evaluated. Two enantioselective LC MS MS methods were validated. A chiral LC MS MS method was chosen as a reference method. The persistence of the stereoisomers in rats biological matrices were different.
|
S0021967320300017
|
Aging refers to the intracellular accumulation of reactive oxygen species that damages proteins DNA and lipids . As alterations in lipid metabolism may trigger metabolic disorders and the onset of metabolic diseases changes in lipid profiles can be closely related to aging . In this study a comprehensive lipidomic comparison between 4 and 25 month old mice was performed to investigate age induced changes in the lipid profiles of mouse serum kidney and heart using nanoflow ultrahigh performance liquid chromatography electrospray ionization tandem mass spectrometry . Quantitative analysis of 279 of the 542 identified lipids revealed significant changes upon aging mainly showing decreased levels in the three types of samples . Exceptionally most triacylglycerols showed significant increases in heart tissue . The kidney was influenced more by aging than the serum and heart . The highly abundant lipids in each lipid class with significant decreases 2 fold
|
Nanoflow UHPLC ESI MS MS of lipids in serum heart and kidney of aged mice. Most lipids with significant changes upon aging were decreased except TG in heart. Lipids in kidney were influenced more by aging than those in heart and serum. Most phosphatidylethanolamines and cardiolipins were reduced in kidney upon aging.
|
S0021967320300029
|
In source fragmentation of ginsenosides in the positive ESI mode frequently occurs which results in little fragment information useful for the structural elucidation . We are aimed to unveil the genesic mechanism and explore its potential significance in quality control of Ginseng and the related compound formulae . By applying six high resolution mass spectrometers from Agilent Waters and Thermo Fisher we could primarily demonstrate the susceptibility of pISF G. The ion clusters in the positive full scan MS
|
ISF of ginsenosides in positive ESI mode was studied systematically. ISF of ginsenosides was examined on six different HRMS instruments. SIM of the sapogenin product ions delineated group target ginsenoside profiles. A novel characteristic chromatogram CC was elaborated for Ginseng. IM SIM CC could identify seven Ginseng and their presence in TCM formulae.
|
S0021967320300030
|
Mixed mode cation exchange stationary phases are useful for the separation of mixtures containing hydrophobic acidic and basic molecules . To ensure that weak organic bases are protonated and carboxylic acids are neutral low pH mobile phases are required . Mixed mode stationary phases that are stable at pH 3 are needed . We synthesized a crosslinked structure along the surface of thiol functionalized silica gel particles using the thiol yne click reaction . The alkyne 1 7 octadiyne was added to the 3 mercaptopropyl silica gel then crosslinked using 1 6 hexanedithiol . Elemental analysis showed low octadiyne ligand surface coverage but stoichiometrically three sulfurs were added to each octadiyne ligand during the crosslinking step indicating that crosslinking occurred . The effect of the crosslinking on the stability was tested with a 50 50 pH 0.50 5 TFA aqueous acetonitrile mobile phase at 70C for six days over 35 000 column volumes . The stationary phase showed good stability with the retention of triphenylene decreasing only 20 during that time . The Tanaka test showed that the phase has a methylene selectivity of 1.200.04 a high shape selectivity of 2.710.03 and a 3.980.05 cation exchange factor at pH 2.70 . The phase has a selectivity factor for nitrobenzene and benzene of 1.410.01 indicating the electron donating charge transfer characteristic of the phase . The mixed mode characteristics of the phase were investigated using a mixture of the monoamine neurotransmitters norepinephrine dopamine and serotonin . Baseline resolution of the monoamines could be obtained using a simple 20mM potassium phosphate methanol mobile phase . Altering both the methanol content and the potassium ion concentration altered the retention of the monoamines indicating mixed mode cation exchange characteristic of the crosslinked stationary phase .
|
Crosslinked stationary phase stable at low pH made with the thiol yne reaction. Electron donating charge transfer characteristics are due to the sulfur in the structure. Mixed mode cation exchange phase is useful with typical reversed phase mobile phases.
|
S0021967320300042
|
This paper describes the development and validation of a new procedure for the determination of phthalates in marine invertebrates based on biocompatible solid phase microextraction followed by liquid chromatography coupled to mass spectrometry . The importance of this application relies on the current use of marine organisms as bioindicators for microplastic contamination through the detection of phthalates in their tissues . Challenges originate from the availability and or possible restriction on the use of the biological materials the need for user friendly procedures for simplifying and speeding up operations in the marine environments and the ubiquitous presence of phthalates in the laboratory environments that may cause background contamination . BioSPME served as an effective solution to all these issues owing to the extreme minimization of the sample manipulation . Sampling operations were limited to the direct transfer of small amounts of the biological materials inside glass vials capped with aluminium lids extractions were carried out by ultrasonication in acetone followed by dilution in ultrapure water and BioSPME clean up Electrospray LCMS MS was employed for the final analytical determinations on the purified extracts . Tests were carried out on samples belonging to three different phyla namely Cnidaria Porifera and Mollusca obtained from Maldivian coral reef environments and used for a current microplastic contamination biomonitoring project . Overall very good sensitivity and repeatability with negligible back contamination of the blanks were observed . The limits of detections were between 0.2 and 2.1ng g and precision calculated as relative standard deviation was below 14 for all the tested phthalates .
|
Phthalates are currently used as markers of microplastic contamination. A BioSPME LC MS method was developed for the analysis of phthalates in marine invertebrates. The method offers control of background contamination. Detection limits were comprised in the 0.22.1ng g range repeatability below 14 RSD. The method was successfully applied for the study of coral reef environments.
|
S0021967320300054
|
Analyses of the complex essential oil samples using gas chromatography hyphenated with mass spectrometry generate large three way data arrays . Processing such large data sets and extracting meaningful information in the metabolic studies of natural products requires application of multivariate statistical techniques . From the GCMS raw data several different input data sets for the MSTs can be created including total chromatogram average mass spectra segmented average mass spectra and chemical composition . Herein we compared the performance of MSTs on average mass spectrum based data sets TCAMS and SAMS against chemical composition and attenuated total reflectance Fourier transformation infrared spectroscopy in the evaluation of quality of ylang ylang essential oils based on their grade geographical origin and chemical composition using principal component analysis partial least squares regression and discriminatory analysis . PCA based on TCAMS SAMS and chemical composition showed clear trends amongst the samples based on increase in grade . PLS DA applied to TCAMS SAMS and ATR FTIR discriminated between all geographical origins . Predicted relative abundances of the 18 most important compounds using PLS regression models on TCAMS SAMS and ATR FTIR were successfully applied to ylang ylang essential oil quality assessment based on comparison with the ISO 3063 2004 standard where the SAMS data set showed superior performance compared to other data sets .
|
TCAMS SAMS and chemical composition derived from GCqMS. Discrimination between ylang ylang essential oil grades and geographical origins. SAMS showed best performance in PCAand PLS regression analysis. PLS prediction of 18 compounds based on TCAMS SAMS and ATR FTIR. Quality control based on comparison of ISO standard and PLS predicted compounds.
|
S0021967320300078
|
Novel solid phase microextraction fibers were fabricated by electrochemical deposition of cobalt on the pretreated nickel titanium alloy fiber substrate and subsequent in situ growth of zeolitic imidazolate framework 67 followed by annealing treatment . The
|
The template directed fabrication of three. coatings on the NiTi wires was developed for SPME. Temperature controlled carbonization was found to be an effective route to manipulate the elemental composition of. coatings. The. coatings showed different extraction capability and selectivity. The. coating was successfully applied to selective enrichment and determination of PAHs in water samples. The. coating showed precisely controllable growth and long term stability of 150 cycles.
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.