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1.
J Sep Sci ; 47(18): e202400521, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39319580

ABSTRACT

The high hydrophobicity and chemical inertness of poly(styrene-divinylbenzene) (PS-DVB) microspheres make their surface hydrophilic modification difficult. Here we describe a facile way to convert PS-DVB microspheres to hydrophilic, then can be used as polar stationary phase for hydrophilic interaction chromatography. This approach utilizes the grafting of an acrylamide-terminated lysine zwitterionic monomer onto PS-DVB microspheres via free radical polymerization. The obtained stationary phase shows good hydrophilicity and a typical retention mechanism of hydrophilic interaction chromatography toward several model polar analytes. It also exhibits obvious zwitterionic properties and is capable of separating cationic and anionic analytes simultaneously. The column shows negligible bleeding level, much superior to silica-based ones.

2.
J Chromatogr A ; 1736: 465333, 2024 Sep 10.
Article in English | MEDLINE | ID: mdl-39260151

ABSTRACT

A zwitterionic stationary phase comprising pyridinium cations and sulfonate anions was successfully developed through thiol-ene click chemistry. Using seven polar small molecules as probes, the zwitterionic stationary phase showed high separation selectivity and excellent column efficiency (35,200-54,800 plates/m) compared with two commercial columns. The influence of water proportion, salt concentration, and pH in the mobile phase, and column temperature, on the retention of six polar compounds was examined. The retention mechanism was explored by three hydrophilic retention models, Tanaka test and linear solvation energy relationship analysis. For the analysis of sample dairy products (milk powder, milk, and yogurt), the stationary phase was operated in hydrophilic interaction chromatography mode without the addition of buffer salts, facilitating rapid and efficient detection and quantification of melamine. The LOD and LOQ are 0.04 mg⋅g-1 and 0.13 mg⋅g-1, respectively, and the recovery rate is 90.3 - 102.8 %. The zwitterionic stationary phase has the advantages of simple preparation, good method reproducibility, good selectivity and high precision.

3.
Talanta ; 275: 126134, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-38692044

ABSTRACT

Phosphoenolpyruvate (PEP) is an essential intermediate metabolite that is involved in various vital biochemical reactions. However, achieving the direct and accurate quantification of PEP in plasma or serum poses a significant challenge owing to its strong polarity and metal affinity. In this study, a sensitive method for the direct determination of PEP in plasma and serum based on ethylenediaminetetraacetic acid (EDTA)-facilitated hydrophilic interaction liquid chromatography-tandem mass spectrometry was developed. Superior chromatographic retention and peak shapes were achieved using a zwitterionic stationary-phase HILIC column with a metal-inert inner surface. Efficient dechelation of PEP-metal complexes in serum/plasma samples was achieved through the introduction of EDTA, resulting in a significant enhancement of the PEP signal. A PEP isotopically labelled standard was employed as a surrogate analyte for the determination of endogenous PEP, and validation assessments proved the sensitivity, selectivity, and reproducibility of this method. The method was applied to the comparative quantification of PEP in plasma and serum samples from mice and rats, as well as in HepG2 cells, HEK293T cells, and erythrocytes; the results confirmed its applicability in PEP-related biomedical research. The developed method can quantify PEP in diverse biological matrices, providing a feasible opportunity to investigate the role of PEP in relevant biomedical research.


Subject(s)
Edetic Acid , Hydrophobic and Hydrophilic Interactions , Phosphoenolpyruvate , Tandem Mass Spectrometry , Tandem Mass Spectrometry/methods , Animals , Humans , Edetic Acid/chemistry , Mice , Chromatography, Liquid/methods , Rats , Phosphoenolpyruvate/chemistry , Phosphoenolpyruvate/blood , Phosphoenolpyruvate/metabolism , HEK293 Cells , Hep G2 Cells , Rats, Sprague-Dawley , Male
4.
J Sep Sci ; 47(1): e2300905, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38143272

ABSTRACT

Simultaneous chromatographic separation of the anomers of saccharides was achieved by using a polymer zwitterionic stationary phase functionalized by acrylamide-type sulfobetaine. By optimization of separation parameters including column temperature, pH, and flow rate, the column operated in hydrophilic interaction chromatography mode exhibited excellent separation selectivity toward five monosaccharides and their anomers (including ribose, xylose, galactose, glucose, and arabinose) and two disaccharides (lactose and maltose). Baseline separation could be achieved at mild operation conditions such as 20-30°C of column temperature or typical mobile phase composition (85% acetrontrile-15% 20 mM ammonium formate [NH4 FA]) with wide pH tolerance range of 2-8. This offers a rapid way to determine the configuration of α or ß anomer of the saccharides.


Subject(s)
Carbohydrates , Polymers , Chromatography , Betaine/chemistry , Hydrophobic and Hydrophilic Interactions
5.
J Chromatogr A ; 1708: 464328, 2023 Oct 11.
Article in English | MEDLINE | ID: mdl-37666063

ABSTRACT

A novel polymer-based polar stationary phase for hydrophilic interaction chromatography (HILIC) is described. It was obtained by grafting lysine and acrylamide onto poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) microspheres via ring-opening reaction of epoxy groups and free radical polymerization with pendant double bonds of the microspheres. Multiple types of polar groups including zwitterionic (carboxylate and amine), amide and diol onto the microspheres make them highly hydrophilic. It showed typical HILIC character and good separation performance towards model polar analytes. Negligible bleed level under gradient elution mode (up to 50% fraction of water) was observed. It also exhibited specific separation selectivity to ionic analytes and simultaneous separation of anions and cations could be achieved in ideal electrostatic selectivity elution order, e.g. I-< NO3-

Subject(s)
Amides , Lysine , Acrylamide , Amines , Chromatography
6.
J Agric Food Chem ; 71(19): 7593-7603, 2023 May 17.
Article in English | MEDLINE | ID: mdl-37139986

ABSTRACT

This work aimed to develop an analytical method for the screening of multiple aminoglycoside residues in foods of animal origin using an ethylene-bridged hybrid (BEH) particle-based sulfoalkylbetaine stationary phase. The effects of chromatographic conditions on the separation of 17 aminoglycosides have been systematically investigated. Sample preparation and mass spectrometry detection have also been investigated and optimized. In contrast to high buffer concentrations in the mobile phase required for silica-based sulfoalkylbetaine stationary phases, a moderate buffer concentration (20 mM) provided the optimal separation of 17 aminoglycosides with the BEH sulfoalkylbetaine stationary phase. The developed method has been evaluated in milk, beef, pork, liver, and honey samples with good performance for retention, selectivity, sensitivity, linearity, precision, and accuracy. The majority of the limit of quantitation estimated with the matrix was less than 25 µg/kg. The overall accuracy across five matrices was in the range from 96 to 111%, with standard deviations of less than 19%.


Subject(s)
Aminoglycosides , Tandem Mass Spectrometry , Animals , Cattle , Aminoglycosides/analysis , Tandem Mass Spectrometry/methods , Chromatography, Liquid/methods , Anti-Bacterial Agents/analysis , Solid Phase Extraction , Ethylenes , Chromatography, High Pressure Liquid/methods
7.
J Chromatogr A ; 1693: 463885, 2023 Mar 29.
Article in English | MEDLINE | ID: mdl-36848731

ABSTRACT

We described two novel zwitterionic polymer-terminated porous silica stationary phases containing the same pyridinium cation and anions of different side chains (carboxylate and phosphonate groups) for use in hydrophilic interaction liquid chromatography (HILIC). These two novel columns were prepared by polymerizing 4-vinylpyridine and grafting it onto a silica surface, followed by quaternization reaction with 3-bromopropionic acid (Sil-VPC24) and (3-bromopropyl) phosphonic acid (Sil-VPP24), which possess positively charged pyridinium groups, and negatively charged carboxylate and phosphonate groups, respectively. The products obtained were verified through relevant characterization techniques such as elemental analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis, Zeta potential analysis, and Brunauer-Emmett-Teller analysis. The retention properties and mechanisms of different types of compounds (neutral, cationic, and anionic) on the two zwitterionic-modified silica stationary phases were studied by varying the buffer salt concentration and pH of the eluent. The separation of phenol and aromatic acids, disubstituted benzene isomers, sulfonamide drugs, as well as nucleosides/nucleobases were investigated on the two packed novel columns and a commercial zwitterionic column in identical HILIC mode, ensuring a thorough comparison between both novel columns and with a commercial standard. The results illustrated that various compounds could be separated up to various efficiencies based on the mechanism of hydrophilic interaction-based retention between the solutes and the two zwitterionic polymer stationary phases. The Sil-VPP24 column demonstrated the best separation performance out of the three, as well as flexible selectivity and excellent resolution. Both novel columns exhibited excellent stability and chromatographic repeatability for the separation of seven nucleosides and bases.


Subject(s)
Nucleosides , Silicon Dioxide , Nucleosides/analysis , Silicon Dioxide/chemistry , Polymers/analysis , Porosity , Chromatography, Liquid/methods , Carboxylic Acids , Hydrophobic and Hydrophilic Interactions
8.
J Chromatogr A ; 1649: 462229, 2021 Jul 19.
Article in English | MEDLINE | ID: mdl-34038779

ABSTRACT

We describe a polymer-based sulfobetaine zwitterionic stationary phase for hydrophilic interaction liquid chromatography (HILIC). It was prepared by grafting acrylamide-type sulfobetaine monomer instead of common methacrylate-type sulfobetaine onto hydrolysed poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) microspheres via pendant double bonds of DVB. The phase has been characterized by elemental analysis, scanning electron micrograph and N2 adsorption-desorption experiment. It shows wider pH tolerance range (from 2 to 12) and excellent separation ability towards common strong polar analytes such as nucleosides and nucleic bases, water-soluble vitamins, amino acids, inorganic anions and cations. Notably, it exhibits negligible baseline noise level (~0.15 pA) under typical HILIC mobile phase. Excellent selectivity in separation of α- and ß-anomers of reducing sugars and lactose/lactulose has also been observed.


Subject(s)
Betaine/analogs & derivatives , Chromatography, Liquid/methods , Polymers/chemistry , Betaine/chemistry , Hydrogen-Ion Concentration , Hydrophobic and Hydrophilic Interactions
9.
Talanta ; 225: 122084, 2021 Apr 01.
Article in English | MEDLINE | ID: mdl-33592796

ABSTRACT

In this paper, a cysteine-functionalized zwitterionic stationary phase (Cys-silica) was prepared based on the "thiol-ene" click chemistry between cysteine and vinyl-functionalized silica, and was further modified with bromoethane, 1-bromooctane and 1-bromooctadecane, respectively, to obtain a series of quaternary ammoniation-functionalized stationary phases (Cys-silica-Cn, n = 2, 8 and 18). These zwitterionic stationary phases were regarded as reversed-phase/ion-exchange (RP/IEC) mixed-mode chromatography (MMC) stationary phases for protein separation. The retention behaviors of proteins on these zwitterionic stationary phases were carefully investigated. The results indicated that the retentions of acidic and basic proteins on these zwitterinonic stationary phases were significantly influenced by the acetonitrile and salt concentrations, pH of mobile phase as well as the hydrophobicity of the ligand. The separation selectivity of proteins on these zwitterionic stationary phases strongly depended on the pH value of mobile phase. The baseline separation of 6 kinds of basic proteins can be achieved at pH 8.0 using Cys-silica-C2 or Cys-silica-C8 column, and 5 kinds of acidic proteins can also be separated completely at pH 4.0 with Cys-silica-C2 column. Moreover, owing to the quaternary ammoniation-functionalization on Cys-silica by using appropriately hydrophobic bromoalkanes, the selectivity and separation efficiency of proteins can be enhanced greatly. As a result, the acidic and basic proteins can be separated completely step by step from the complex sample by adjusting pH of mobile phase using a single Cys-silica-C2 column, which illustrates that the cysteine-functionalized zwitterionic stationary phase has a great potential for protein separation.


Subject(s)
Click Chemistry , Cysteine , Chromatography, Ion Exchange , Hydrogen-Ion Concentration , Hydrophobic and Hydrophilic Interactions , Silicon Dioxide
10.
Talanta ; 216: 120927, 2020 Aug 15.
Article in English | MEDLINE | ID: mdl-32456936

ABSTRACT

We describe a novel polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography (HILIC). It is prepared by chemical modification of poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) by converting epoxide groups of microsphere surface to diol groups via hydrolysis, then clicking cysteine onto the microsphere with pendant double bonds of microsphere surface via "thiol-ene" click chemistry. The phase has been characterized by scanning electron micrograph, elemental analysis and zeta potential measurement. Diol and zwitterionic group (carboxylate and amine group associated with cysteine) onto the surface of GMA-DVB microspheres make them possess good hydrophilicity, as supported by effective separation towards common polar analytes. It shows good stability at alkaline solution (e.g. pH 10) and negligible bleed (e.g. only 1.7-fold blank and ~55-fold lower than a commercial silica-based polar phase tested with the minimal bleed level). Such phase exhibits specific separation selectivity to ionic analytes and simultaneous separation of anions and cations is achieved in the retention order of I- < NO3- < Choline < Br- < Cl- < K+< Na+.

11.
J Sep Sci ; 43(6): 1071-1079, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31883201

ABSTRACT

Surface-bonded zwitterionic stationary phases have shown highlighted performances in separation of polar and hydrophilic compounds under hydrophilic interaction chromatography mode. So, it would be helpful to evaluate the characteristics of zwitterionic stationary phases with different arranged charged groups. The present work involved the preparation and comparison of three zwitterionic stationary phases. An imidazolium ionic liquid was designed and synthesized, and the cationic and anionic moieties respectively possessed positively charged imidazolium ring and negatively charged sulfonic groups. Then, the prepared ionic liquid, phosphorylcholine and an imidazolium-based zwitterionic selector were bonded on the surface of silica to obtain three zwitterionic stationary phases. The selectivity properties were characterized and compared through the relative retention of selected solute pairs, and different kinds of hydrophilic solutes mixtures were used to evaluate the chromatographic performances. Moreover, the zwitterionic stationary phases were further characterized by the modified linear solvation energy relationship model to probe the multiple interactions. All the results indicated that the types and arrangement of charged groups in zwitterionic stationary phases mainly affect the retention and separation of ionic or ionizable compounds, and for interaction characteristics the contribution from n and π electrons and electrostatic interactions displayed certain differences.

12.
Se Pu ; 37(7): 683-691, 2019 Jul 08.
Article in Chinese | MEDLINE | ID: mdl-31271007

ABSTRACT

The present study focuses on the preparation and application of zwitterionic stationary phases with controllable ratios of positively charged amino groups and negatively charged phosphonic acid groups. Successful grafting was confirmed by elemental analysis and evaluation of pore structure characteristics. Additionally, the proportion of amino and phosphonic acid groups could be easily determined by the mass fractions of N and P. In this study, three types of amino phosphate-based zwitterionic surface-bonded stationary phases (APS) were prepared with different ratios of amino and phosphonic acid groups. The resulting APS silica materials were slurry-packed into stainless-steel columns (150 mm×4.6 mm). Various parameters such as column temperature, water content, pH, and ionic strength of the mobile phase were investigated to evaluate the chromatographic characteristics of the APS columns. A mixed-mode retention mechanism involving surface adsorption, partitioning, and electrostatic interactions was revealed. Finally, a set of test mixtures (nucleosides, water-soluble vitamins, benzoic acids, and basic compounds) were employed to evaluate the separation selectivity and retention characteristics of the three prepared APS stationary phases. The APS phases demonstrated entirely different selectivity and retention behavior for various polar analytes under the same conditions, thus demonstrating excellent application potential for the analysis of polar compounds in hydrophilic interaction chromatography (HILIC).

13.
J Chromatogr A ; 1593: 110-118, 2019 May 24.
Article in English | MEDLINE | ID: mdl-30739756

ABSTRACT

A polymeric reversed-phase/weak anion exchange (Poly-RP/WAX) mixed-mode stationary phase has been prepared by coating of a poly(3-mercaptopropyl)methylsiloxane film on vinyl-modified silica (100 Å, 5 µm) and simultaneous in situ functionalization with N-(10-undecenoyl)-3-aminoquinuclidine as well as crosslinking to the vinyl silica surface by solventless thiol-ene double click reaction. Such bonding chemistry showed greatly enhanced stability compared to brush-type analogs with bifunctional siloxane bonding to silica. Solid-state 29Si-CP/MAS NMR confirmed the immobilization of the siloxane layer. pH-Dependent ζ-potential determinations revealed a high anion-exchange capacity over the entire pH range with a maximum around pH 5. Oxidation of residual thiols yielded a zwitterionic Poly-RP/WAX/SCX mixed-mode phase with sulfonic acid endcapping and shifted the still net positive surface charge to lower ζ-potentials. It allowed a faster elution of strongly retained anionic species in particular of multiply negatively charged analytes such as oligonucleotides. Chromatographic tests under RPLC and HILIC elution mode with various test substances documented the multimodal utility and complementarity in retention profiles compared to RP, HILIC and commercial mixed-mode phases.


Subject(s)
Chromatography, Ion Exchange/methods , Chromatography, Reverse-Phase/methods , Click Chemistry/methods , Polyvinyls/chemistry , Siloxanes/chemistry , Sulfhydryl Compounds/chemistry , Anions/chemistry , Polymers/chemistry
14.
Anal Bioanal Chem ; 410(23): 5941-5950, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29968107

ABSTRACT

4-Hydroxy-D-phenylglycine was modified with methacrylic anhydride and then immobilized on silica through thiol-initiated surface polymerization; the prepared material was applied as stationary phase for HPLC. The obtained stationary phase was characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The chromatographic performance of the packed column was evaluated in reversed-phase liquid chromatograph (RPLC) and hydrophilic interaction liquid chromatograph (HILIC) mode; this column has shown excellent selectivity to both the hydrophobic and hydrophilic solutes. The selectivity towards polycyclic aromatic hydrocarbons relative to that towards alkylbenzenes exhibited by the prepared column was higher than the corresponding selectivity exhibited by commercial C18 column, which could be explained by electronic π-π interaction between phenylglycine and electron-rich aromatic rings. On the other hand, the prepared column has also shown better selectivity for polar compounds, which was based on the multiple interaction and retention mechanisms. It was also used to separate sulfonamides and organic acid compared with a commercial C18 and HILIC column; the results show its great chromatographic performance with distinctive selectivity. All the results indicated the prepared column had potential application in a wide range.


Subject(s)
Chromatography, Reverse-Phase/methods , Glycine/analogs & derivatives , Acids/isolation & purification , Chromatography, High Pressure Liquid/methods , Glycine/chemistry , Hydrophobic and Hydrophilic Interactions , Polymerization , Silicon Dioxide/chemistry , Sulfhydryl Compounds/chemistry , Sulfonamides/isolation & purification
15.
Anal Chim Acta ; 963: 136-142, 2017 Apr 22.
Article in English | MEDLINE | ID: mdl-28335967

ABSTRACT

A methacrylate based monolith, containing the innovative zwitterionic monomer (3-allyl-1-imidazol)propane sulfonate, was prepared in 100 µm I.D. silica capillaries by UV initiated photo-polymerization. Composition of the porogen, i.e. a mixture of 1-propanol, 1,4 butanediol and water, was of great importance to obtain a homogeneous monolith with satisfactory permeability and good electrochromatographic performance. Morphology of the stationary phase was studied in Scanning Electron Microscopy and IR experiments, which revealed a good attachment to the capillary wall, flowthrough-pores in the range of 0.5-2 µm, and a continuous monolithic structure. The developed material was well suited for the analysis of six common phenolic acids (salicylic, cinnamic, syringic, rosmarinic, caffeic and chlorogenic acid) by CEC. Their separation was possible in less than 8 min with a mobile phase comprising a 12 mM aqueous ammonium acetate solution with pH 8.5 and acetonitrile, at an applied voltage of - 20 kV. The developed method was validated (R2 ≥ 0.995; LOD ≤ 3.9 µg mL-1, except for salicylic acid; recovery rates from 94 to 104%) and successfully used for the determination of phenolic acids in Coffea arabica samples. All of them contained cinnamic, syringic and caffeic acid, however only in unroasted coffee beans chlorogenic acid (0.06%) was found. The quantitative results were in good agreement to reported literature data.


Subject(s)
Capillary Electrochromatography/methods , Coffee/chemistry , Hydroxybenzoates/isolation & purification , Imidazoles/chemistry , Plant Extracts/chemistry
16.
Talanta ; 161: 860-866, 2016 Dec 01.
Article in English | MEDLINE | ID: mdl-27769494

ABSTRACT

Zwitterionic polymer stationary phases have attracted increasing attention in hydrophilic interaction chromatography (HILIC). In this work, a zwitterionic sulfobetaine functionalized polyacrylamide stationary phase (named TENS) based on porous silica particles was prepared via controlled surface initiated reversible addition-fragmentation transfer (RAFT) polymerization. Instead of traditional methacrylate type sulfobetaine monomer, acrylamide type sulfobetaine monomer, which has higher chemical stability and hydrophicility, was employed in this work. The characterization of elemental analysis and solid-state 13C cross polarization/magic-angle-spinning nuclear magnetic resonance indicated the successful preparation of TENS stationary phase. Meanwhile, scanning electron microscope (SEM), nitrogen adsorption experiment and study of size exclusion performance were conducted, revealing that the surface initiated polymerization was well controlled. For better understanding of TENS material under HILIC mode, chromatographic evaluation of TENS material was performed, among which, TENS material exhibited good hydrophilicity and chemical stability. To further study the applicability of TENS material, saccharides which were considered as challenging targets in HILIC, were chosen as tested analytes. Various saccharide samples, including fructooligosaccharide, trisaccharide isomers and ginsenosides, were well separated on TENS material. Moreover, TENS material displayed good selectivity for the enrichment of glycopeptides. These results demonstrated the capability of TENS as a promising material in glycomics and glycoproteomics.


Subject(s)
Acrylic Resins/chemistry , Betaine/analogs & derivatives , Silicon Dioxide/chemistry , Betaine/chemistry , Chromatography, Liquid/methods , Glycopeptides/chemistry , Hydrophobic and Hydrophilic Interactions , Immunoglobulin G/chemistry , Polymerization , Polysaccharides/chemistry
17.
Carbohydr Res ; 427: 29-37, 2016 Jun 02.
Article in English | MEDLINE | ID: mdl-27085741

ABSTRACT

Lipopolysaccharide (LPS, endotoxin) is a main surface antigen and virulence factor of Gram-negative bacteria. Regardless of the source of LPS, this molecule, isolated from the smooth forms of bacteria, is characterised by a general structural layout encompassing three regions: (i) an O-specific polysaccharide (O-PS) - a polymer of repeating oligosaccharide units, (ii) core oligosaccharide (OS), and (iii) the lipid A anchoring LPS in the outer membrane of the cell envelope of Gram-negative bacteria. Structural analysis usually requires degradation of LPS and further efficient separation of various poly- and oligosaccharide glycoforms. The hydrophilic interaction liquid chromatography (HILIC) was shown as an efficient technique for separation of labelled or native neutral and acidic glycans, glycopeptides, sialylated glycans, glycosylated and nonglycosylated peptides. Herein we adopted ZIC(®) (zwitterionic stationary phase covalently attached to porous silica)-HILIC technology in combination with electrospray ionisation mass spectrometry to separate different LPS-derived oligosaccharides. As a result three effective procedures have been developed: (i) to separate different core oligosaccharides of Escherichia coli R1 LOS, (ii) to separate RU-[Hep]-Kdo oligosaccharides from core OS glycoforms of Hafnia alvei PCM 1200 LPS, and (iii) to separate Hep and Kdo-containing mono, di-, tri- and tetrasaccharides of H. alvei PCM 1200 LPS. Moreover, some of developed analytical procedures were scaled to semi-preparative protocols and used to obtain highly-purified fractions of the interest in larger quantities required for future evaluation, analysis, and biological applications.


Subject(s)
Chromatography, Liquid/methods , Gram-Negative Bacteria/metabolism , Oligosaccharides/isolation & purification , Spectrometry, Mass, Electrospray Ionization/methods , Bacterial Proteins/analysis , Chemical Fractionation , Escherichia coli/metabolism , Hafnia alvei/metabolism , Hydrophobic and Hydrophilic Interactions , Lipopolysaccharides/analysis
18.
Talanta ; 141: 8-14, 2015 Aug 15.
Article in English | MEDLINE | ID: mdl-25966373

ABSTRACT

The present study described the preparation and application of zwitterionic stationary phases (ACS) with controllable ratio of positively charged tertiary amine groups and negatively charged carboxyl groups. Various parameters, including water content, pH values and ionic strength of the mobile phase, were investigated to study the chromatographic characteristics of ACS columns. The prepared ACS columns demonstrated a mix-mode retention mechanism composed of surface adsorption, partitioning and electrostatic interactions. The elemental analysis of different batches of the ACS phases demonstrated good reproducibility of the preparation strategy. Additionally, various categories of compounds, including nucleosides, water-soluble vitamins, benzoic acid derivatives and basic compounds were successively employed to evaluate the separation selectivity of the prepared ACS stationary phases. These ACS phases exhibited entirely different selectivity and retention behavior from each other for various polar analytes, demonstrating the excellent application potential in the analysis of polar compounds in HILIC.


Subject(s)
Chromatography, High Pressure Liquid/methods , Adsorption , Benzoic Acid/analysis , Benzoic Acid/chemistry , Chromatography, High Pressure Liquid/instrumentation , Gas Chromatography-Mass Spectrometry , Hydrogen-Ion Concentration , Hydrophobic and Hydrophilic Interactions , Magnetic Resonance Spectroscopy , Nucleosides/analysis , Osmolar Concentration , Reproducibility of Results , Silanes/analysis , Silanes/chemistry , Static Electricity , Vitamins/analysis
19.
J Chromatogr A ; 1362: 168-79, 2014 Oct 03.
Article in English | MEDLINE | ID: mdl-25160959

ABSTRACT

It has been reported that HILIC column chemistry has a great effect on the number of detected metabolites in LC-HRMS-based untargeted metabolite profiling studies. However, no systematic investigation has been carried out with regard to the optimisation of mobile phase characteristics. In this study using 223 metabolite standards, we explored the retention mechanisms on three zwitterionic columns with varied mobile phase composition, demonstrated the interference from poor chromatographic peak shapes on the output of data extraction, and assessed the quality of chromatographic signals and the separation of isomers under each LC condition. As expected, on the ZIC-cHILIC column the acidic metabolites showed improved chromatographic performance at low pH which can be attributed to the opposite arrangement of the permanently charged groups on this column in comparison with the ZIC-HILIC column. Using extracts from the protozoan parasite Leishmania, we compared the numbers of repeatedly detected LC-HRMS features under different LC conditions with putative identification of metabolites not amongst the standards being based on accurate mass (±3ppm). Besides column chemistry, the pH of the mobile phase plays a key role in not only determining the retention mechanisms of solutes but also the output of the LC-HRMS data processing. Fast evaporation of ammonium carbonate produced less ion suppression in ESI source and consequently improved the detectability of the metabolites in low abundance in comparison with other ammonium salts. Our results show that the combination of a ZIC-pHILIC column with an ammonium carbonate mobile phase, pH 9.2, at 20mM in the aqueous phase or 10mM in both aqueous and organic mobile phase components, provided the most suitable LC conditions for LC-HRMS-based untargeted metabolite profiling of Leishmania parasite extracts. The signal reliability of the mass spectrometer used in this study (Exactive Orbitrap) was also investigated.


Subject(s)
Chromatography, High Pressure Liquid/methods , Leishmania major/chemistry , Metabolomics/methods , Spectrometry, Mass, Electrospray Ionization/methods , Animals , Hydrogen-Ion Concentration , Ions/chemistry , Leishmania major/metabolism , Reproducibility of Results , Water/chemistry
20.
J Chromatogr A ; 1314: 63-9, 2013 Nov 01.
Article in English | MEDLINE | ID: mdl-24075460

ABSTRACT

As a naturally hydrophilic peptide, glutathione was facilely immobilized onto silica surface to obtain a novel hydrophilic interaction/cation-exchange mixed-mode chromatographic stationary phase (Click TE-GSH) via copper-free "thiol-ene" click chemistry. The resulting material was characterized by solid state (13)C/CP MAS NMR and elemental analysis. The measurement of ζ-potential indicated the cation-exchange characteristics and adjustable surface charge density of Click TE-GSH material. The influence of acetonitrile content and pH value on the retention of ionic compounds was investigated for understanding the chromatographic behaviors. The results demonstrated that Click TE-GSH column could provide both hydrophilic and cation-exchange interaction. Taking advantage of the good hydrophilicity and inherent cation-exchange characteristics of Click TE-GSH material, the resolution of neutral fructosan with high degree of polymerization (DP), basic chitooligosaccharides and strongly acidic carrageenan oligosaccharides was successfully realized in hydrophilic interaction chromatography (HILIC), hydrophilic interaction/cation-exchange mixed-mode chromatography (HILIC/CEX), cation-exchange chromatography (CEX) and electrostatic repulsion/hydrophilic interaction chromatography (ERLIC). On the other hand, the separation of standard peptides varying in hydrophobicity/hydrophilicity and charge was achieved in both CEX and HILIC/CEX mode with high efficiency and distinct selectivity. To further demonstrate the versatility and applicability of Click TE-GSH stationary phase, the separation of a human serum albumin (HSA) tryptic digest was performed in HILIC/CEX mode. Peptides were adequately resolved and up to 86 HSA peptides were identified with sequence coverage of 85%. The results indicated the good potential of Click TE-GSH material in glycomics and proteomics.


Subject(s)
Cation Exchange Resins , Chromatography, Ion Exchange/methods , Glutathione/analysis , Carbohydrates/analysis , Chromatography, Ion Exchange/instrumentation , Hydrophobic and Hydrophilic Interactions , Magnetic Resonance Spectroscopy , Mass Spectrometry , Peptides/analysis , Serum Albumin/chemistry
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