626 results match your criteria column mixed-mode


Comparing the relative robustness of anion exchange and the corresponding mixed-mode chromatography on removing a weakly-bound byproduct: A case study of bispecific antibody purification.

Protein Expr Purif 2021 Jul 22;187:105948. Epub 2021 Jul 22.

Technology and Process Development (TPD), WuXi Biologics, 288 Fute Zhong Road, Waigaoqiao Free Trade Zone, Shanghai, 200131, China. Electronic address:

A certain impurity may bind weaker or tighter to a particular type of chromatography column (e.g., ion exchange, hydrophobic interaction or mixed-mode) than the target protein, and this forms the basis for separation. Read More

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Surface-confined guanidinium ionic liquid as a new type of stationary phase for hydrophilic interaction liquid chromatography.

J Sep Sci 2021 Jul 16. Epub 2021 Jul 16.

State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China.

Guanidinium-based ionic liquids possess lower toxicity and greater designability than commonly used species and have presented good performances in liquid-phase extraction and stationary phase for capillary GC. In the present work, a novel type of surface-confined guanidinium ionic liquid stationary phase was developed by bonding a hexaalkylguanidinium ionic liquid N,N,N',N'-tetramethyl-N",N"-diallylguanidinium bromide onto the surface of 3-mercaptopropyl modified silica. The obtained surface-confined guanidinium ionic liquid silica materials were characterized by elemental analysis, infrared spectrum, and thermogravimetric analysis, and then packed as a HPLC column for the evaluation of chromatographic retention behavior. Read More

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A comprehensive study on the performance of different retention mechanisms in sport drug testing by liquid chromatography tandem mass spectrometry.

J Chromatogr B Analyt Technol Biomed Life Sci 2021 Jul 3;1178:122821. Epub 2021 Jun 3.

Department of Analytical Chemistry, Institute of Fine Chemistry and Nanochemistry, Marie Curie Building (Annex), Campus of Rabanales, University of Córdoba, 14071 Córdoba, Spain.

Anti-doping substances listed by the World Anti-Doping Agency (WADA) include hundreds of compounds of very different physico-chemical properties. Anti-doping control laboratories need to screen all these substances in the so-called Initial Testing Procedures (ITPs) what is very challenging from an analytical point of view. ITPs are mostly based on reversed-phase (RP) liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using C18 columns, which feature poor retention and peak tailing for polar and basic compounds, respectively. Read More

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Facile fabrication of [email protected] organic polymers core-shell composites as the mixed-mode stationary phase for hydrophilic interaction/reversed-phase/ion-exchange chromatography.

Talanta 2021 Oct 15;233:122524. Epub 2021 May 15.

School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China. Electronic address:

Covalent organic polymers (COPs) are a promising class of cross-linked polymeric networks that attracted extensive attention in separation and analysis fields. Exploring facile and convenient strategy to prepare COPs-based mixed-mode stationary phases for high performance liquid chromatography (HPLC) has seriously lagged and has never been reported. Herein, we describe a facile in-situ grow strategy for fabrication of [email protected] core-shell composites ([email protected](OH)) as a novel mixed-mode stationary phase for HPLC. Read More

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October 2021

[Preparation and chromatographic properties of 1-vinyl-3-dodecylimidazole bromide silica-bonded stationary phase].

Se Pu 2020 Nov;38(11):1263-1269

College of Pharmaceutical Sciences, Hebei University, Baoding 071002, China.

As the main components of cell membranes, lipids play important roles in organisms. Lipids have been proved to be closely associated with the occurrence and development of serious diseases, such as cancers and metabolic diseases. The development of novel separation materials for use in high-performance liquid chromatography (HPLC) is essential for high-efficiency lipid separation. Read More

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November 2020

Isocratic reporter-exclusion immunoassay using restricted-access adsorbents.

Analyst 2021 Aug 2;146(15):4835-4840. Epub 2021 Jul 2.

Department of Biology and Biochemistry, University of Houston, Houston, TX, USA.

We introduce analyte-dependent exclusion of reporter reagents from restricted-access adsorbents as the basis of an isocratic reporter-exclusion immunoassay for viruses, proteins, and other analytes. Capto™ Core 700 and related resins possess a noninteracting size-selective outer layer surrounding a high-capacity nonspecific mixed-mode capture adsorbent core. In the absence of analyte, antibody-enzyme reporter conjugates can enter the adsorbent and be captured, and their signal is lost. Read More

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Characterization of the new Celeris Arginine column: Retentive behaviour through a combination of chemometric tools and potential in drug analysis.

J Chromatogr A 2021 Aug 4;1651:462316. Epub 2021 Jun 4.

CASSMedChem Research Group, Molecular Biotechnology and Health Sciences Department, University of Turin, Italy. Electronic address:

Celeris Arginine (ARG) is a mixed-mode stationary phase recently released on the market. To characterize its analytical behavior, the retention factors of a pool (n=100, of which 36 neutrals, 26 acids and 38 bases) of pharmaceutically relevant compounds have been measured on this phase over eight percentages (from 10 to 90% v/v) of acetonitrile (MeCN) as organic modifier. The ARG phase exhibited enhanced affinity for the molecules that are in their anionic form at the experimental pH, whilst basic compounds, albeit over a wide range of lipophilicity and pK values, were on average poorly retained. Read More

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High stability amino-derived reversed-phase/anion-exchange mixed-mode phase based on polysilsesquioxane microspheres for simultaneous separation of compound drugs.

J Pharm Biomed Anal 2021 Sep 3;203:114187. Epub 2021 Jun 3.

School of Pharmaceutical Science & Technology, Tianjin University, 92 Weijin Road, Tianjin, 300072, China. Electronic address:

A series of amino-derived mixed-mode chromatographic stationary phases were synthesized based on porous mercaptopropyl-functionalized polysilsesquioxane mesoporous microspheres synthesized by a co-condensation of methyltrimethoxysilane (MTMS) and mercaptopropyltrimethoxysilane (MPTMS). Through controlling the ratio of MTMS and MPTMS, the modified stationary phases with different amino densities were prepared by a "thiol-ene" click chemistry reaction. The morphology, pore structure, and functional groups of the microspheres were characterized by scanning electron microscope (SEM), nitrogen adsorption-desorption test, Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and zeta potential, respectively. Read More

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September 2021

A novel approach for the preparation of core-shell MOF/polymer composites as mixed-mode stationary phase.

Talanta 2021 Sep 8;232:122459. Epub 2021 May 8.

CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China. Electronic address:

The nickel organic framework capped with polyvinylpyrrolidone was prepared and synergistically immobilized onto porous silica surface as the mixed-mode stationary phase for high-performance liquid chromatography. Here, polyvinylpyrrolidone firstly was chosen as functional molecules to change morphology and size of the metal organic framework. The silica microspheres were then modified by them via a simple bonding method rather than in-situ growth method with the aid of electrostatic interaction commonly used before. Read More

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September 2021

Analysis of filtration behavior using integrated column chromatography followed by virus filtration.

Biotechnol Bioeng 2021 May 25. Epub 2021 May 25.

Bioprocess Division, Department of Technology, Asahi Kasei Medical Co., Ltd., Nobeoka-shi, Miyazaki-ken, Japan.

We evaluated filtration behavior and virus removal capability for a monoclonal antibodies (mAb) and plasma IgG under constant flow rate directly following flow-through column chromatography in an integrated process. mAb solution with quantified host cell protein (HCP) content processed in flow-through mode on in-series mixed-mode AEX and modified CEX columns connected to the Planova BioEX filter (pool-less) achieved HCP logarithmic reduction value (LRV) of 2.3 and 93. Read More

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Comparison of human IgG glycopeptides separation using mixed-mode hydrophilic interaction/ion-exchange liquid chromatography and reversed-phase mode.

Anal Bioanal Chem 2021 Jul 17;413(16):4321-4328. Epub 2021 May 17.

Department of Analytical Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43, Prague 2, Czech Republic.

Glycoproteomics is a challenging branch of proteomics because of the micro- and macro-heterogeneity of protein glycosylation. Hydrophilic interaction liquid chromatography (HILIC) is an advantageous alternative to reversed-phase chromatography for intact glycopeptide separation prior to their identification by mass spectrometry. Nowadays, several HILIC columns differing in used chemistries are commercially available. Read More

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Reversed-phase and weak anion-exchange mixed-mode stationary phase for fast separation of medium-, long- and very long chain free fatty acids by ultra-high-performance liquid chromatography-high resolution mass spectrometry.

J Chromatogr A 2021 Jul 3;1648:462209. Epub 2021 May 3.

Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, Parma 43124, Italy. Electronic address:

Two commercial stationary phases allowing both reversed phase mechanism and anion-exchange with different selectivity, i.e. CSH C and Atlantis PREMIER BEH C AX, were tested for the separation of a complex mixture of 21 fatty acids (FAs) encompassing saturated medium-, long- and very long chain FAs, unsaturated long and very long chain FAs, cis/trans isomers, and isomers of odd- and branched-chain FAs. Read More

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Characterization and comparison of mixed-mode and reversed-phase columns; interaction abilities and applicability for peptide separation.

J Chromatogr A 2021 Jul 27;1648:462182. Epub 2021 Apr 27.

Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 12843, Czech Republic. Electronic address:

In this work, two mixed-mode columns from a different manufacturers and one marketed as a reversed-phase column were characterized and compared in the terms of their interaction abilities, retentivity, peak symmetry, and applicability for peptide separation. All the tested columns contain octadecyl ligand and positively charged modifier, i.e. Read More

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Influence of the mobile phase composition on hyphenated ultraviolet and charged aerosol detection for the impurity profiling of vigabatrin.

J Pharm Biomed Anal 2021 Jul 3;201:114110. Epub 2021 May 3.

University of Würzburg, Institute for Pharmacy and Food Chemistry, 97074, Würzburg, Germany. Electronic address:

Recently, charged aerosol detection (CAD), a universal detection technique in liquid chromatography, has been introduced into monographs of the European Pharmacopoeia (Ph. Eur.), which now employs HPLC-UV-CAD for assessing the impurities of the drug vigabatrin. Read More

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Mixed-mode open tubular column for peptide separations by capillary electrochromatography.

J Sep Sci 2021 Jul 31;44(13):2602-2611. Epub 2021 May 31.

Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.

Mixed-mode chromatography open tubular column has been developed for peptide separation in electrochromatography. A column with 92 cm effective length and 50 μm internal diameter is fabricated internally with a copolymer sheet of restricted thickness. Catalyst facilitated binding of the coupling agent 3,5-bis (trifluoromethyl) phenyl isocyanate has been carried out at the interior surface of the column. Read More

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Development of a sensitive direct injection LC-MS/MS method for the detection of glyphosate and aminomethylphosphonic acid (AMPA) in hard waters.

Anal Bioanal Chem 2021 Jun 12;413(14):3763-3774. Epub 2021 Apr 12.

Department of Civil and Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, NC, 27708-0287, USA.

Glyphosate is currently the most widely used herbicide in the world; however, the zwitterionic and highly polar properties of glyphosate make current pesticide analysis methods unsuitable for its trace analysis in natural waters. Additionally, current glyphosate analysis methods do not account for waters of varying hardness, which is vital as glyphosate can complex with cationic species such as Ca and Mg in the environment. We detail here a robust LC-MS/MS method for the quantitation of glyphosate and its primary transformation product aminomethylphosphonic acid (AMPA) in environmental waters of varying water hardness. Read More

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Bioactivity-guided separation of antifungal compounds by preparative high-performance liquid chromatography.

J Sep Sci 2021 Jun 12;44(12):2382-2390. Epub 2021 May 12.

Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.

Bioactivity-guided chromatographic methods are of great significance for the isolation of the active compounds in complex samples. In this study, four anti-fungal compounds were located by activity screening and successfully isolated from a microbial fermentation sample by preparative high-performance liquid chromatography. Separation performance of columns including C18, positively charged C18, negatively charged C18 and C8 were firstly investigated. Read More

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Electrospray ionization mass spectrometry ion suppression/enhancement caused by column bleed for three mixed-mode reversed-phase/anion-exchange high-performance liquid chromatography columns.

Rapid Commun Mass Spectrom 2021 Jun;35(12):e9098

Waters Corporation, 34 Maple Street, Milford, MA, USA.

Rationale: Mixed-mode reversed-phase/anion exchange liquid chromatography is useful for separations of mixtures containing anions (e.g. ionized acids). Read More

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Perspective on the Future Approaches to Predict Retention in Liquid Chromatography.

Authors:
Fabrice Gritti

Anal Chem 2021 04 2;93(14):5653-5664. Epub 2021 Apr 2.

Waters Corporation, 34 Maple Street, Milford, Massachusetts 01757, United States.

The demand for rapid column screening, computer-assisted method development and method transfer, and unambiguous compound identification by LC/MS analyses has pushed analysts to adopt experimental protocols and software for the accurate prediction of the retention time in liquid chromatography (LC). This Perspective discusses the classical approaches used to predict retention times in LC over the last three decades and proposes future requirements to increase their accuracy. First, inverse methods for retention prediction are essentially applied during screening and gradient method optimization: a minimum number of experiments or design of experiments (DoE) is run to train and calibrate a model (either purely statistical or based on the principles and fundamentals of liquid chromatography) by a mere fitting process. Read More

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Simultaneous separation of insulin and six therapeutic analogues on a mixed mode column: HPLC-UV method development and application.

J Chromatogr B Analyt Technol Biomed Life Sci 2021 May 20;1171:122557. Epub 2021 Jan 20.

Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.

Human insulin and six most used therapeutic analogues are very similar in terms of retention on a reversed-phase column. Thus, the LC methods prescribed in the European Pharmacopoeia monographs for insulin and insulin analogues include many similar separation methods, which tend to be time consuming when separating individual products of insulins or are inadequate when handling a mixture. In this study, we present a simple, robust, versatile and accessible HPLC-UV separation method for identification and quantification of human insulin and its analogues in one run. Read More

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Amphipathic carbon quantum dots-functionalized silica stationary phase for reversed phase/hydrophilic interaction chromatography.

Talanta 2021 May 29;226:122148. Epub 2021 Jan 29.

College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao, 266109, China. Electronic address:

Carbon quantum dots (CQDs) are considered as good chromatographic separation materials. However, due to the hydrophily of the synthesized CQDs, their applications in HPLC are limited to HILIC for separating strong polar compounds only. In this work, a novel amphipathic CQDs with both hydrophobicity and hydrophily is developed as mixed-mode stationary phase for RPLC/HILIC. Read More

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Clogging sensitivity of flow distributors designed for radially elongated hexagonal pillar array columns: a computational modelling.

Sci Rep 2021 Mar 2;11(1):4927. Epub 2021 Mar 2.

BioMEMS and Bioinspired Microfluidic Laboratory, Department of Mechanical and Manufacturing Engineering, Centre for Bioengineering Research and Education (CBRE), Biomedical Engineering Program, University of Calgary, Mechanical Engineering Building, MEB214, 2500 University Dr., N.W., Calgary, AB, T2N 1N4, Canada.

Flow distributor located at the beginning of the micromachined pillar array column (PAC) has significant roles in uniform distribution of flow through separation channels and thus separation efficiency. Chip manufacturing artifacts, contaminated solvents, and complex matrix of samples may contribute to clogging of the microfabricated channels, affect the distribution of the sample, and alter the performance of both natural and engineered systems. An even fluid distribution must be achieved cross-sectionally through careful design of flow distributors and minimizing the sensitivity to clogging in order to reach satisfactory separation efficiency. Read More

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Multiplexed small molecule impurity monitoring in antibody-based therapeutics by mixed-mode chromatography paired with charged aerosol detection.

J Pharm Biomed Anal 2021 Apr 4;197:113952. Epub 2021 Feb 4.

Small Molecule Analytical Chemistry, Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, United States. Electronic address:

With advanced genetic engineering technologies and better understanding of disease biology, antibody-based therapeutics are emerging as promising new generation biopharmaceuticals. These novel antibody formats are carefully designed to possess desired features such as enhanced selectivity. However, their high level of structural complexity with multiple components often leads to long development and complex multi-step manufacturing processes, through which a variety of potential small molecule impurities can be introduced. Read More

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pH-dependent selective separation of acidic and basic proteins using quaternary ammoniation functionalized cysteine-zwitterionic stationary phase with RPLC/IEC mixed-mode chromatography.

Talanta 2021 Apr 7;225:122084. Epub 2021 Jan 7.

Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Institute of Modern Separation Science, Key Lab of Modern Separation Science in Shaanxi Province, Northwest University, Xi'an, 710069, China. Electronic address:

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-C, 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. Read More

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One-step preparation of cyclen-containing hydrophilic polymeric monolithic materials via epoxy-amine ring-opening reaction and their application in enrichment of N-glycopeptides.

Talanta 2021 Apr 24;225:122049. Epub 2020 Dec 24.

CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China.

Considering the special structure of 1,4,7,10-tetraazacyclododecane (cyclen) which is easy to form complexes with ions, it is beneficial to achieve particular selectivity. Cyclen was selected as a precursor to react with triglycidyl isocyanurate (TGIC), and a novel kind of hydrophilic polymeric monolithic material was facilely prepared via epoxy-amine ring-opening reaction in the presence of a binary porogenic system of acetonitrile (ACN) and polyethylene glycol. The resulting poly (TGIC-co-cyclen) monolithic column was used to separate both nonpolar alkylbenzenes using mobile phase of ACN/HO (35/65, v/v) and polar phenolic compounds and anilines under the mobile phase of ACN/HO (60/40, v/v) in reversed-phase capillary liquid chromatography (cLC). Read More

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Design and evaluation of novel MOF-polymer core-shell composite as mixed-mode stationary phase for high performance liquid chromatography.

Mikrochim Acta 2021 Feb 9;188(3):76. Epub 2021 Feb 9.

CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China.

A general method was developed for preparing a metal-organic framework-polymer composite coated silica core-shell stationary phase. Silica microspheres were comodified with metal-organic framework and polyvinylpyrrolidone rather than the in situ method of silica modification by original metal-organic framework particles. Metal-organic framework particles and polyvinylpyrrolidone on silica surface were beneficial to suppress silanol activity and enhance composite material tolerance, as well as increasing the water compatibility of the original metal-organic framework-based stationary phases. Read More

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February 2021

A validated LC-MS/MS method for the simultaneous quantification of the novel combination antibiotic, ceftolozane-tazobactam, in plasma (total and unbound), CSF, urine and renal replacement therapy effluent: application to pilot pharmacokinetic studies.

Clin Chem Lab Med 2021 Apr 25;59(5):921-933. Epub 2020 Nov 25.

UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, Australia.

Objectives: Novel treatment options for some carbapenem-resistant Gram-negative pathogens have been identified by the World Health Organization as being of the highest priority. Ceftolozane-tazobactam is a novel cephalosporin-beta-lactamase inhibitor combination antibiotic with potent bactericidal activity against the most difficult-to-treat multi-drug resistant and extensively drug resistant Gram-negative pathogens. This study aimed to develop and validate a liquid chromatography - tandem mass spectrometry method for the simultaneous quantification of ceftolozane and tazobactam in plasma (total and unbound), renal replacement therapy effluent (RRTE), cerebrospinal fluid (CSF) and urine. Read More

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Comprehensive ethoxymer characterization of complex alcohol ethoxy sulphate products by mixed-mode high-performance liquid chromatography coupled to charged aerosol detection.

J Chromatogr A 2021 Feb 21;1639:461927. Epub 2021 Jan 21.

Department of Analysis, CEPSA Research Center, Alcalá de Henares, 28805, Spain. Electronic address:

The present work describes a simultaneous mixed-mode high performance liquid chromatography (HPLC) method combined with a universal and non-selective-response detector for the complete ethoxymer profiling of alcohol ethoxy sulphate mixtures. The optimized HPLC methodology combines the dual hydrophilic (HILIC) and reversed-phase selectivity of a surfactant-type column in order to render a comprehensive and simultaneous separation of more than 50 endogenous ethoxymers in a single analysis. Furthermore, an accurate quantitation of every single analyte was achieved using a final universal charged aerosol detector (CAD) including specific mathematical processing tools. Read More

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February 2021

Characterization of stationary phases in supercritical fluid chromatography including exploration of shape selectivity.

J Chromatogr A 2021 Feb 20;1639:461923. Epub 2021 Jan 20.

University of Orleans, ICOA, CNRS UMR 7311; Pôle de chimie rue de Chartres - BP 6759 45067, Orléans Cedex 2, France. Electronic address:

Achiral packed column supercritical fluid chromatography (SFC) has shown an important regain of interest in academic and industrial laboratories in the recent years. In relation to this increased concern, major instrument manufacturers have designed some stationary phases specifically for SFC use. SFC stationary phases have been widely examined over the last two decades, based on the use of linear solvation energy relationships (LSER), which relate analyte retention to its properties and to the interaction capabilities of the chromatographic system. Read More

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February 2021