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Salido-Fortuna S, Ruano-Culebras P, Marina ML, Castro-Puyana M. Rapid indirect separation of glutamine enantiomers by micellar electrokinetic chromatography. Analysis of dietary supplements. J Sep Sci 2024; 47:e2300921. [PMID: 38356221 DOI: 10.1002/jssc.202300921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 02/16/2024]
Abstract
Glutamine is the most abundant free proteinogenic α-amino acid. It is naturally produced in the organism and acts as a precursor for the synthesis of different biologically important molecules (such as proteins or nucleotides). However, under stressful conditions, the organism is unable to produce it in enough amounts to function properly. Thus, glutamine (Gln)-based supplements have become increasingly popular over the last decade. Since legal regulations establish that amino acid-based dietary supplements must contain only the L-enantiomer and not the racemate, adequate chiral methodologies are required to achieve their quality control. In this work, an analytical methodology based on the use of micellar electrokinetic chromatography is proposed for the rapid enantiomeric determination of DL-Gln in dietary supplements. Using (+)-1-(9-fluorenyl)-ethyl chloroformate as a derivatizing agent and ammonium perfluorooctanoate as separation medium, the Gln diastereoisomers formed under optimal conditions were separated in 8 min with a resolution of 2.8. The analytical characteristics of the method were evaluated in terms of linearity, precision, accuracy, and limits of detection/quantitation, and they were found appropriate for the analysis of L-Gln-based dietary supplements.
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Affiliation(s)
- Sandra Salido-Fortuna
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | - Paloma Ruano-Culebras
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | - María Luisa Marina
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
- Instituto de Investigación Química Andrés M. del Río, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | - María Castro-Puyana
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
- Instituto de Investigación Química Andrés M. del Río, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
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2
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Orlandini S, Hancu G, Szabó ZI, Modroiu A, Papp LA, Gotti R, Furlanetto S. New Trends in the Quality Control of Enantiomeric Drugs: Quality by Design-Compliant Development of Chiral Capillary Electrophoresis Methods. Molecules 2022; 27:molecules27207058. [PMID: 36296650 PMCID: PMC9607418 DOI: 10.3390/molecules27207058] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/16/2022] Open
Abstract
Capillary electrophoresis (CE) is a potent method for analyzing chiral substances and is commonly used in the enantioseparation and chiral purity control of pharmaceuticals from different matrices. The adoption of Quality by Design (QbD) concepts in analytical method development, optimization and validation is a widespread trend observed in various analytical approaches including chiral CE. The application of Analytical QbD (AQbD) leads to the development of analytical methods based on sound science combined with risk management, and to a well understood process clarifying the influence of method parameters on the analytical output. The Design of Experiments (DoE) method employing chemometric tools is an essential part of QbD-based method development, allowing for the simultaneous evaluation of experimental parameters as well as their interaction. In 2022 the International Council for Harmonization (ICH) released two draft guidelines (ICH Q14 and ICH Q2(R2)) that are intended to encourage more robust analytical procedures. The ICH Q14 guideline intends to harmonize the scientific approaches for analytical procedures’ development, while the Q2(R2) document covers the validation principles for the use of analytical procedures including the recent applications that require multivariate statistical analyses. The aim of this review is to provide an overview of the new prospects for chiral CE method development applied for the enantiomeric purity control of pharmaceuticals using AQbD principles. The review also provides an overview of recent research (2012–2022) on the applicability of CE methods in chiral drug impurity profiling.
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Affiliation(s)
- Serena Orlandini
- Department of Chemistry “U. Schiff”, University of Florence, 50019 Florence, Italy
| | - Gabriel Hancu
- Department of Pharmaceutical and Therapeutic Chemistry, Faculty of Pharmacy, University of Medicine, Pharmacy, Science and Technology “George Emil Palade” of Târgu Mureș, 540139 Târgu Mureș, Romania
- Correspondence:
| | - Zoltán-István Szabó
- Department of Pharmaceutical Industry and Management, Faculty of Pharmacy, University of Medicine, Pharmacy, Science and Technology “George Emil Palade” of Târgu Mureș, 540139 Târgu Mureș, Romania
| | - Adriana Modroiu
- Department of Pharmaceutical and Therapeutic Chemistry, Faculty of Pharmacy, University of Medicine, Pharmacy, Science and Technology “George Emil Palade” of Târgu Mureș, 540139 Târgu Mureș, Romania
| | - Lajos-Attila Papp
- Department of Pharmaceutical and Therapeutic Chemistry, Faculty of Pharmacy, University of Medicine, Pharmacy, Science and Technology “George Emil Palade” of Târgu Mureș, 540139 Târgu Mureș, Romania
| | - Roberto Gotti
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Sandra Furlanetto
- Department of Chemistry “U. Schiff”, University of Florence, 50019 Florence, Italy
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3
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Bogos LG, Pralea IE, Moldovan RC, Iuga CA. Indirect Enantioseparations: Recent Advances in Chiral Metabolomics for Biomedical Research. Int J Mol Sci 2022; 23:ijms23137428. [PMID: 35806433 PMCID: PMC9267260 DOI: 10.3390/ijms23137428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 01/27/2023] Open
Abstract
Chiral metabolomics is starting to become a well-defined research field, powered by the recent advances in separation techniques. This review aimed to cover the most relevant advances in indirect enantioseparations of endogenous metabolites that were published over the last 10 years, including improvements and development of new chiral derivatizing agents, along with advances in separation methodologies. Moreover, special emphasis is put on exciting advances in separation techniques combined with mass spectrometry, such as chiral discrimination by ion-mobility mass spectrometry together with untargeted strategies for profiling of chiral metabolites in complex matrices. These advances signify a leap in chiral metabolomics technologies that will surely offer a solid base to better understand the specific roles of enantiomeric metabolites in systems biology.
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Affiliation(s)
- Luisa-Gabriela Bogos
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MEDFUTURE, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania; (L.-G.B.); (I.-E.P.); (C.-A.I.)
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, “Iuliu Hațieganu” University of Medicine and Pharmacy, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania
| | - Ioana-Ecaterina Pralea
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MEDFUTURE, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania; (L.-G.B.); (I.-E.P.); (C.-A.I.)
| | - Radu-Cristian Moldovan
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MEDFUTURE, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania; (L.-G.B.); (I.-E.P.); (C.-A.I.)
- Correspondence:
| | - Cristina-Adela Iuga
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MEDFUTURE, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania; (L.-G.B.); (I.-E.P.); (C.-A.I.)
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, “Iuliu Hațieganu” University of Medicine and Pharmacy, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania
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4
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Capillary Electrophoresis Mass Spectrometry: Developments and Applications for Enantioselective Analysis from 2011–2020. Molecules 2022; 27:molecules27134126. [PMID: 35807372 PMCID: PMC9268241 DOI: 10.3390/molecules27134126] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 06/15/2022] [Accepted: 06/21/2022] [Indexed: 12/01/2022] Open
Abstract
It is now more than 25 years since the first report of enantioselective analysis by capillary electrophoresis-mass spectrometry (CE-MS) appeared. This article reviews the power of chiral CE-MS in resolving issues on the use of chiral selector incompatibility with MS and poor detectability encountered for chiral compounds by UV detection. The review begins with the general principles, requirements, and critical aspects of chiral CE-MS instrumentation. Next, the review provides a survey of MS-compatible chiral selectors (CSs) reported during the past decade, and the key achievements encountered in the time period using these CSs. Within the context of the strategies used to combine CE and MS, special attention is paid to the approaches that feature partial filling technique, counter-migration techniques, and direct use of CS, such as molecular micelles. In particular, the development and application of moving and fixed CS for EKC-MS, MEKC-MS, and CEC-MS demonstrate how various chiral compounds analyses were solved in a simple and elegant way during the 2010–2020 review period. The most noteworthy applications in the determination of chiral compounds are critically examined. The operating analytical conditions are detailed in the Tables, and the authors provide commentary on future trends of chiral separations by CE-MS.
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5
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Wang A, Liu K, Tian M, Yang L. Open Tubular Capillary Electrochromatography-Mass Spectrometry for Analysis of Underivatized Amino Acid Enantiomers with a Porous Layer-Gold Nanoparticle-Modified Chiral Column. Anal Chem 2022; 94:9252-9260. [PMID: 35713648 DOI: 10.1021/acs.analchem.2c00233] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
By developing a novel chiral column, we integrate open tubular capillary electrochromatography into sheathless mass spectrometry (MS) for efficient analysis of underivatized amino acid enantiomers. The chiral column is easily fabricated by modifying the inner surface of a capillary with a three-dimensional porous layer (PL, thickness ∼ 90 nm, pore size ∼ 30 nm) and gold nanoparticles and by introducing a chiral selector, thiol β-cyclodextrin (SH-β-CD), onto the modified surface via Au-S bonds. This approach greatly enhances the specific surface area and thus the ratio of the stationary phase to mobile phase and interaction between the stationary phase and analytes. The proposed PLOT@Au@CD column is coupled to the sheathless CE-ESI-MS system for chiral analysis of amino acid enantiomers. No derivatization of amino acids is required for chiral analysis, and baseline separation of a total of 15 pairs of amino acid enantiomers is achieved within 17 min with high column efficiencies of 5.60 × 104 to 1.82 × 106 N/m, high resolutions of 1.51-10.0, and low limits of detection between 0.02 and 0.09 μg/mL. The separation efficiency and MS intensity are only slightly decreased over 60 runs or after usage for 15 days, showing excellent repeatability and stability of the PLOT@Au@CD column. The proposed method is successfully applied to the determination of amino acid enantiomers in vinegar samples with satisfactory accuracy. Our study provides a new approach for developing a chiral stationary phase in the chromatographic separation technique, which can be easily coupled to sensitive MS detection, thus it would be of value for various applications in the fields of chiral analysis.
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Affiliation(s)
- Anping Wang
- Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province, Department of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun, Jilin Province 130024, China
| | - Kexin Liu
- Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province, Department of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun, Jilin Province 130024, China.,Hangzhou Puyu Technology Development Co. Ltd, Hangzhou, Zhejiang Province, 311300, China
| | - Miaomiao Tian
- Institute of Chemical and Industrial Bioengineering, Jilin Engineering Normal University, 3050 Kaixuan Road, Changchun, Jilin Province, 130052, China
| | - Li Yang
- Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province, Department of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun, Jilin Province 130024, China
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6
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Simultaneous Determination of Twenty Amino Acids in In Vitro Fertilization Medium by the HPLC–MS/MS Method. Chromatographia 2022. [DOI: 10.1007/s10337-022-04169-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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Piestansky J, Olesova D, Matuskova M, Cizmarova I, Chalova P, Galba J, Majerova P, Mikus P, Kovac A. Amino acids in inflammatory bowel diseases: Modern diagnostic tools and methodologies. Adv Clin Chem 2022; 107:139-213. [PMID: 35337602 DOI: 10.1016/bs.acc.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Amino acids are crucial building blocks of living organisms. Together with their derivatives, they participate in many intracellular processes to act as hormones, neuromodulators, and neurotransmitters. For several decades amino acids have been studied for their potential as markers of various diseases, including inflammatory bowel diseases. Subsequent improvements in sample pretreatment, separation, and detection methods have enabled the specific and very sensitive determination of these molecules in multicomponent matrices-biological fluids and tissues. The information obtained from targeted amino acid analysis (biomarker-based analytical strategy) can be further used for early diagnostics, to monitor the course of the disease or compliance of the patients. This review will provide an insight into current knowledge about inflammatory bowel diseases, the role of proteinogenic amino acids in intestinal inflammation and modern analytical techniques used in its diagnosis and disease activity monitoring. Current advances in the analysis of amino acids focused on sample pretreatment, separation strategy, or detection methods are highlighted, and their potential in clinical laboratories is discussed. In addition, the latest clinical data obtained from the metabolomic profiling of patients suffering from inflammatory bowel diseases are summarized with a focus on proteinogenic amino acids.
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Affiliation(s)
- Juraj Piestansky
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia; Toxicological and Antidoping Center, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Dominika Olesova
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Michaela Matuskova
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Ivana Cizmarova
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Petra Chalova
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Jaroslav Galba
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Petra Majerova
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Peter Mikus
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia; Toxicological and Antidoping Center, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Andrej Kovac
- Institute of Neuroimmunology, Slovak Academy of Sciences, Bratislava, Slovakia.
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8
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Bernardo-Bermejo S, Marina ML, Castro-Puyana M. A rapid electrokinetic chromatography method using short-end injection for the enantioselective separation of tryptophan. Microchem J 2021. [DOI: 10.1016/j.microc.2021.106508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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9
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Oliveira RV, Simionato AVC, Cass QB. Enantioselectivity Effects in Clinical Metabolomics and Lipidomics. Molecules 2021; 26:molecules26175231. [PMID: 34500665 PMCID: PMC8433918 DOI: 10.3390/molecules26175231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 12/22/2022] Open
Abstract
Metabolomics and lipidomics have demonstrated increasing importance in underlying biochemical mechanisms involved in the pathogenesis of diseases to identify novel drug targets and/or biomarkers for establishing therapeutic approaches for human health. Particularly, bioactive metabolites and lipids have biological activity and have been implicated in various biological processes in physiological conditions. Thus, comprehensive metabolites, and lipids profiling are required to obtain further advances in understanding pathophysiological changes that occur in cells and tissues. Chirality is one of the most important phenomena in living organisms and has attracted long-term interest in medical and natural science. Enantioselective separation plays a pivotal role in understanding the distribution and physiological function of a diversity of chiral bioactive molecules. In this context, it has been the goal of method development for targeted and untargeted metabolomics and lipidomic assays. Herein we will highlight the benefits and challenges involved in these stereoselective analyses for clinical samples.
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Affiliation(s)
- Regina V. Oliveira
- SEPARARE-Núcleo de Pesquisa em Cromatografia, Department of Chemistry, Federal University of São Carlos, Rod. Washington Luiz, Km 235, São Carlos 13565-905, SP, Brazil;
| | - Ana Valéria C. Simionato
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas, Campinas 13083-970, SP, Brazil;
- National Institute of Science and Technology for Bioanalytics, Institute of Chemistry, University of Campinas, Campinas 13083-970, SP, Brazil
| | - Quezia B. Cass
- SEPARARE-Núcleo de Pesquisa em Cromatografia, Department of Chemistry, Federal University of São Carlos, Rod. Washington Luiz, Km 235, São Carlos 13565-905, SP, Brazil;
- Correspondence: ; Tel.: +55-16-3351-8087
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10
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de Koster N, Clark CP, Kohler I. Past, present, and future developments in enantioselective analysis using capillary electromigration techniques. Electrophoresis 2021; 42:38-57. [PMID: 32914880 PMCID: PMC7821218 DOI: 10.1002/elps.202000151] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 08/22/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022]
Abstract
Enantioseparation of chiral products has become increasingly important in a large diversity of academic and industrial applications. The separation of chiral compounds is inherently challenging and thus requires a suitable analytical technique that can achieve high resolution and sensitivity. In this context, CE has shown remarkable results so far. Chiral CE offers an orthogonal enantioselectivity and is typically considered less costly than chromatographic techniques, since only minute amounts of chiral selectors are needed. Several CE approaches have been developed for chiral analysis, including chiral EKC and chiral CEC. Enantioseparations by EKC benefit from the wide variety of possible pseudostationary phases that can be employed. Chiral CEC, on the other hand, combines chromatographic separation principles with the bulk fluid movement of CE, benefitting from reduced band broadening as compared to pressure-driven systems. Although UV detection is conventionally used for these approaches, MS can also be considered. CE-MS represents a promising alternative due to the increased sensitivity and selectivity, enabling the chiral analysis of complex samples. The potential contamination of the MS ion source in EKC-MS can be overcome using partial-filling and counter-migration techniques. However, chiral analysis using monolithic and open-tubular CEC-MS awaits additional method validation and a dedicated commercial interface. Further efforts in chiral CE are expected toward the improvement of existing techniques, the development of novel pseudostationary phases, and establishing the use of chiral ionic liquids, molecular imprinted polymers, and metal-organic frameworks. These developments will certainly foster the adoption of CE(-MS) as a well-established technique in routine chiral analysis.
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Affiliation(s)
- Nicky de Koster
- Leiden Academic Centre for Drug Research, Division of Systems Biomedicine and PharmacologyLeiden UniversityLeidenThe Netherlands
| | - Charles P. Clark
- Leiden Academic Centre for Drug Research, Division of Systems Biomedicine and PharmacologyLeiden UniversityLeidenThe Netherlands
| | - Isabelle Kohler
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute for Molecular and Life SciencesVrije Universiteit AmsterdamAmsterdamThe Netherlands
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11
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Zeid AM, Nasr JJM, Belal F, Walash M, Kaji N, Baba Y. Microfluidic fast chiral separation of baclofen and phenylalanine enantiomers based on cyclodextrin-electrokinetic chromatography. Microchem J 2021. [DOI: 10.1016/j.microc.2020.105770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Violi JP, Bishop DP, Padula MP, Steele JR, Rodgers KJ. Considerations for amino acid analysis by liquid chromatography-tandem mass spectrometry: A tutorial review. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.116018] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Xu W, Zhong C, Zou C, Wang B, Zhang N. Analytical methods for amino acid determination in organisms. Amino Acids 2020; 52:1071-1088. [PMID: 32857227 DOI: 10.1007/s00726-020-02884-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 08/18/2020] [Indexed: 02/07/2023]
Abstract
Amino acids are important metabolites for tissue metabolism, growth, maintenance, and repair, which are basic life necessities. Therefore, summarizing analytical methods for amino acid determination in organisms is important. In the past decades, analytical methods for amino acids have developed rapidly but have not been fully explored. Thus, this article provides reference to analytical methods for amino acids in organisms for food and human research. Present amino acid analysis methods include thin-layer chromatography, high-performance liquid chromatography, liquid chromatography-mass spectrometer, gas chromatography-mass spectrometry, capillary electrophoresis, nuclear magnetic resonance, and amino acid analyzer analysis.
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Affiliation(s)
- Weihua Xu
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, 1200 Cai-lun Rd, Shanghai, 201203, China
- State Key Laboratory of Drug Research and Center for Pharmaceutics Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Hai-ke Rd, Shanghai, 201203, China
- School of Pharmacy, Anhui University of Traditional Chinese Medicine, Anhui, 230013, China
| | - Congcong Zhong
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, 1200 Cai-lun Rd, Shanghai, 201203, China
| | - Chunpu Zou
- School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Bing Wang
- State Key Laboratory of Drug Research and Center for Pharmaceutics Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Hai-ke Rd, Shanghai, 201203, China.
| | - Ning Zhang
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, 1200 Cai-lun Rd, Shanghai, 201203, China.
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14
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Chiral Micellar Electrokinetic Chromatography. J Chromatogr A 2020; 1626:461383. [PMID: 32797856 DOI: 10.1016/j.chroma.2020.461383] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 12/18/2022]
Abstract
The potential of Micellar Electrokinetic Chromatography to achieve enantiomeric separations is reviewed in this article. The separation principles and the most frequently employed separation strategies to achieve chiral separations by Micellar Electrokinetic Chromatography are described. The use of chiral micellar systems alone or combined with other micellar systems or chiral selectors, as well as of mixtures of achiral micellar systems with chiral selectors is discussed together with the effect of different additives present in the separation medium. Indirect methods based on the derivatization of analytes with chiral derivatizing reagents and the use of achiral micelles are also considered. Preconcentration techniques employed to improve sensitivity and the main approaches developed to facilitate the coupling with Mass Spectrometry are included. The most recent and relevant methodologies developed by chiral Micellar Electrokinetic Chromatography and their applications in different fields are presented.
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15
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Enantioanalysis of glutamine—a key factor in establishing the metabolomics process in gastric cancer. Anal Bioanal Chem 2020; 412:3199-3207. [DOI: 10.1007/s00216-020-02575-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/21/2020] [Accepted: 03/03/2020] [Indexed: 12/16/2022]
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16
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Bernardo-Bermejo S, Sánchez-López E, Castro-Puyana M, Marina ML. Chiral capillary electrophoresis. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.115807] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Pérez-Míguez R, Marina ML, Castro-Puyana M. A micellar electrokinetic chromatography approach using diastereomeric derivatization and a volatile surfactant for the enantioselective separation of selenomethionine. Electrophoresis 2019; 40:1951-1958. [PMID: 31111508 DOI: 10.1002/elps.201900077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 05/16/2019] [Accepted: 05/18/2019] [Indexed: 11/06/2022]
Abstract
A MEKC methodology with UV detection was developed for the enantioselective separation of selenomethionine (SeMet). The use of (+)-1-(9-fluorenyl)ethyl chloroformate (FLEC) as chiral derivatization reagent to form SeMet diastereomers enabled their subsequent separation using ammonium perfluorooctanoate (APFO) as a volatile pseudostationary phase. The effect of APFO concentration and pH, temperature, injection volume, and derivatization conditions (time and FLEC/SeMet ratio) were evaluated in order to select the best separation conditions. A chiral resolution of 4.4 for DL-SeMet was achieved in less than 6 min using 100 mM APFO at pH 8.5 as electrophoretic buffer. Satisfactory results were obtained in terms of linearity, precision (RSD from 3.4 to 5.1% for migration times and from 1.8 to 4.6% for corrected peak areas), accuracy, and LODs (3.1 × 10-6 M and 3.7 × 10-6 M for d and l enantiomers, respectively). The method was successfully applied to the determination of l-SeMet in food supplements.
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Affiliation(s)
- Raquel Pérez-Míguez
- Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Ciencias, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - Maria Luisa Marina
- Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Ciencias, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain.,Instituto de Investigación Química Andrés M. del Río (IQAR), Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - María Castro-Puyana
- Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Ciencias, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain.,Instituto de Investigación Química Andrés M. del Río (IQAR), Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
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18
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Kubáň P, Dvořák M, Kubáň P. Capillary electrophoresis of small ions and molecules in less conventional human body fluid samples: A review. Anal Chim Acta 2019; 1075:1-26. [PMID: 31196414 DOI: 10.1016/j.aca.2019.05.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/02/2019] [Accepted: 05/03/2019] [Indexed: 01/05/2023]
Abstract
In recent years, advances in sensitive analytical techniques have encouraged the analysis of various compounds in biological fluids. While blood serum, blood plasma and urine still remain the golden standards in clinical, toxicological and forensic science, analyses of other body fluids, such as breast milk, exhaled breath condensate, sweat, saliva, amniotic fluid, cerebrospinal fluid, or capillary blood in form of dried blood spots are becoming more popular. This review article focuses on capillary electrophoresis and microchip electrophoresis of small ions and molecules (e.g. inorganic cations/anions, basic/acidic drugs, small acids/bases, amino acids, peptides and other low molecular weight analytes) in various less conventional human body fluids and hopes to stimulate further interest in the field.
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Affiliation(s)
- Petr Kubáň
- Institute of Analytical Chemistry of the Czech Academy of Sciences, Veveří 97, CZ-60200, Brno, Czech Republic
| | - Miloš Dvořák
- Institute of Analytical Chemistry of the Czech Academy of Sciences, Veveří 97, CZ-60200, Brno, Czech Republic
| | - Pavel Kubáň
- Institute of Analytical Chemistry of the Czech Academy of Sciences, Veveří 97, CZ-60200, Brno, Czech Republic.
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19
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Pérez-Míguez R, Bruyneel B, Castro-Puyana M, Marina ML, Somsen GW, Domínguez-Vega E. Chiral Discrimination of DL-Amino Acids by Trapped Ion Mobility Spectrometry after Derivatization with (+)-1-(9-Fluorenyl)ethyl Chloroformate. Anal Chem 2019; 91:3277-3285. [PMID: 30682252 PMCID: PMC6404107 DOI: 10.1021/acs.analchem.8b03661] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
![]()
A novel analytical
method based on hybrid trapped ion mobility
spectrometry-time-of-flight mass spectrometry (TIMS-TOFMS) has been
developed to achieve fast enantiomeric separation of amino acids (AAs).
Resolution of chiral AAs was achieved by forming diastereomers through
derivatization with the chiral agent (+)-1-(9-fluorenyl)ethyl chloroformate
(FLEC), avoiding the use of reference compounds. Electrospray ionization
(ESI) in positive mode yielded sodiated FLEC-AAs ions of which the
diastereomers could be separated by TIMS. The effect of other alkali
metal ions (such as Li and K) on the enantioselectivity was studied,
but chiral discrimination was only observed for Na. TIMS conditions,
including voltage ramp, ramp time, and accumulation time were optimized
for each AA, and collision cross sections (CCSs) were determined for
all diastereomers. The migration order of the DL enantiomers was found
to be dependent on the structure of the AA. The resulting TIMS resolution
(K0/ΔK0) for the FLEC-AA diastereomers on average was 115, requiring
a mobility (K0) difference of about 0.009 cm2/(V s) to
achieve 50%-valley separation. From the 21 AAs studied, enantiomer
separation was achieved for 17 AAs with mobility differences ranging
from 0.009 for lysine up to 0.061 cm2/(V s) for asparagine.
Moreover, the presented methodology provided mutual separation of
various AAs, allowing chiral analysis of multiple AAs simultaneously
which may be challenging with previous enantioselective IMS approaches.
It appeared possible to fully resolve all studied DL-AAs using three
distinct TIMS methods, resulting in a total MS run time of about 3
min (1 min per method) and a total analysis time (including derivatization)
of less than 15 min. The method demonstrated capable to determine
enantiomeric ratios down to 2.5% with detection limits for the D enantiomers
in the nanomolar range. This new TIMS-based methodology opens up possibilities
for easy and fast analysis of AA enantiomers.
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Affiliation(s)
- Raquel Pérez-Míguez
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Department of Chemistry and Pharmaceutical Sciences , Vrije Universiteit Amsterdam , de Boelelaan 1085 , 1081 HV Amsterdam , The Netherlands.,Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Faculty of Sciences , University of Alcalá , Carretera Madrid-Barcelona Km. 33600 , 28871 , Alcalá de Henares , Madrid , Spain
| | - Ben Bruyneel
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Department of Chemistry and Pharmaceutical Sciences , Vrije Universiteit Amsterdam , de Boelelaan 1085 , 1081 HV Amsterdam , The Netherlands
| | - María Castro-Puyana
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Faculty of Sciences , University of Alcalá , Carretera Madrid-Barcelona Km. 33600 , 28871 , Alcalá de Henares , Madrid , Spain
| | - María Luisa Marina
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Faculty of Sciences , University of Alcalá , Carretera Madrid-Barcelona Km. 33600 , 28871 , Alcalá de Henares , Madrid , Spain
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Department of Chemistry and Pharmaceutical Sciences , Vrije Universiteit Amsterdam , de Boelelaan 1085 , 1081 HV Amsterdam , The Netherlands
| | - Elena Domínguez-Vega
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and Systems, Department of Chemistry and Pharmaceutical Sciences , Vrije Universiteit Amsterdam , de Boelelaan 1085 , 1081 HV Amsterdam , The Netherlands
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20
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Shanmuganathan M, Britz-McKibbin P. New Advances in Amino Acid Profiling in Biological Samples by Capillary Electrophoresis-Mass Spectrometry. Methods Mol Biol 2019; 2030:327-350. [PMID: 31347129 DOI: 10.1007/978-1-4939-9639-1_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Capillary electrophoresis-mass spectrometry (CE-MS) offers a high efficiency microseparation platform for amino acid profiling when analyzing volume-restricted biological samples, such as a dried blood spot punch. Direct analysis of amino acids and their analogs is routinely achieved using strongly acidic buffer conditions under positive-ion mode detection with a coaxial sheath liquid interface for electrospray ionization (ESI). New advances in online sample preconcentration, pre-column chemical derivatization, and/or low flow/sheathless CE-MS interface designs can further improve sensitivity while allowing for resolution of amino acid stereoisomers and labile aminothiols with low nanomolar detection limits. Additionally, multiplexed separations in CE-MS based on serial injection of seven or more samples within a single run greatly boosts sample throughput (<2-3 min/sample) without added infrastructure costs while allowing for stringent quality control and signal batch correction. Accurate prediction of the electromigration behavior of amino acids and their analogs offers a convenient approach for structural elucidation that is complementary to high-resolution MS and MS/MS. Simultaneous analysis of amino acids together with other classes of ionic metabolites by CE-MS allows for comprehensive metabolomic screening as required for new advances in clinical medicine, nutritional sciences, and population health.
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Affiliation(s)
- Meera Shanmuganathan
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada
| | - Philip Britz-McKibbin
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada.
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21
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Abstract
Capillary electrophoresis (CE) is a well-established and one of the most powerful separation techniques in the field of chiral separations. Its hyphenation with mass spectrometry (MS) combines both the high separation efficiency and low sample consumption of CE and the high sensitivity and structural information of MS. Thus, the outstanding chiral resolution power of CE along with the MS advantages makes CE-MS a perfect combination to achieve sensitive enantioseparations. This chapter describes three representative examples of different approaches used in the chiral analysis of amino acids in biological fluids by CE-MS. The first methodology uses the partial filling technique to avoid the entry of cyclodextrins in the MS source. The second method shows the possibility to carry out the direct coupling EKC-MS even when a relative high concentration of a native cyclodextrin is used as chiral selector. The last example illustrates an alternative strategy based on the formation of stable diastereomers between an enantiomerically pure chiral reagent and the amino acids enantiomers which can be separated in an achiral environment.
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22
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Shanmuganathan M, Britz-McKibbin P. New Advances for Newborn Screening of Inborn Errors of Metabolism by Capillary Electrophoresis-Mass Spectrometry (CE-MS). Methods Mol Biol 2019; 1972:139-163. [PMID: 30847789 DOI: 10.1007/978-1-4939-9213-3_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Expanded newborn screening of inborn errors of metabolism (IEM) based on tandem mass spectrometry (MS/MS) technology is one of the most successful preventative healthcare initiatives for presymptomatic diagnosis and treatment of rare yet treatable genetic diseases in the population. However, confirmatory testing of presumptive screen-positive cases is required using high efficiency separations for improved specificity in order to improve the positive predictive value (PPV) for certain classes of IEMs. Here, we describe recent advances using capillary electrophoresis-mass spectrometry (CE-MS) for reliable second-tier screening or confirmatory testing based on targeted analysis of amino acids, acylcarnitines, nucleosides, and other classes of polar metabolites associated with IEMs. Additionally, nontargeted metabolite profiling enables the identification of unknown biomarkers of clinical significance for other genetic diseases that are currently screened by bioassays and/or mutation panels, such as cystic fibrosis (CF). Noteworthy, CE-MS allows for resolution of isobaric/isomeric interferences without complicated sample handling that is ideal when analyzing volume-restricted biospecimens from neonates/infants, including dried blood spots and sweat specimens. New developments to improve concentration sensitivity, as well as enhance sample throughput and quality control for unambiguous confirmatory testing of IEMs will also be discussed when using multiplexed separations based on multisegment injection-CE-MS.
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Affiliation(s)
- Meera Shanmuganathan
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada
| | - Philip Britz-McKibbin
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada.
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23
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Lee S, Kim SJ, Bang E, Na YC. Chiral separation of intact amino acids by capillary electrophoresis-mass spectrometry employing a partial filling technique with a crown ether carboxylic acid. J Chromatogr A 2018; 1586:128-138. [PMID: 30558847 DOI: 10.1016/j.chroma.2018.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 11/24/2018] [Accepted: 12/01/2018] [Indexed: 12/19/2022]
Abstract
An enantiomeric separation method for underivatized free amino acids (AAs) using a partial filling technique with CE-MS was developed for the determination of D-AAs in vinegars. A typical chiral separation method was performed with different concentrations of (18-crown-6)-2,3,11,12-tetracarboxylic acid (18C6H4) dissolved in water or formic acid as the background electrolyte. Seventeen AAs, excluding proline and asparagine, were separated, showing chiral resolution values (Rs) ranging from 0.5 to 21.0. These results included baseline separations of 11 AAs, the peaks of which were observed as the ions [AA+18C6H4+H]+. The migration order of the chiral AAs was also evaluated, and the L-AAs migrated faster than the counterpart D-AAs except for serine, threonine and methionine when using (+)-18C6H4. To reduce contamination of the ESI source by the nonvolatile chiral selector and improve the ionization efficiency in partial filling technique, the separation zone length was adjusted to 70% of the capillary, which was filled with 30 mM 18C6H4 in water. This method showed a similar separation efficiency as the typical method, and the separated AA peaks were observed as free AA ions, [AA+H]+. The optimized method provided limits of detection (LODs) ranging from 0.07 to 1.03 μg/mL and good linearity (R2 > 0.99) up to 50 μg/mL for DL-AAs. The developed method was utilized to determine DL-AAs in vinegars with a simple pretreatment process. It may be extended to sensitive AA analysis in the determination of minor enantiomeric impurities in the major component.
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Affiliation(s)
- Sul Lee
- Western Seoul Center, Korea Basic Science Institute, 150 Bugahyeon-ro, Seodaemun-gu, Seoul 03759, Republic of Korea; Department of Chemistry and Nano Science, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
| | - Su-Jin Kim
- Western Seoul Center, Korea Basic Science Institute, 150 Bugahyeon-ro, Seodaemun-gu, Seoul 03759, Republic of Korea; Department of Food Science & Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
| | - Eunjung Bang
- Western Seoul Center, Korea Basic Science Institute, 150 Bugahyeon-ro, Seodaemun-gu, Seoul 03759, Republic of Korea
| | - Yun-Cheol Na
- Western Seoul Center, Korea Basic Science Institute, 150 Bugahyeon-ro, Seodaemun-gu, Seoul 03759, Republic of Korea; Department of Chemistry and Nano Science, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea.
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24
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Stolz A, Jooß K, Höcker O, Römer J, Schlecht J, Neusüß C. Recent advances in capillary electrophoresis-mass spectrometry: Instrumentation, methodology and applications. Electrophoresis 2018; 40:79-112. [PMID: 30260009 DOI: 10.1002/elps.201800331] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/06/2018] [Accepted: 09/07/2018] [Indexed: 12/14/2022]
Abstract
Capillary electrophoresis (CE) offers fast and high-resolution separation of charged analytes from small injection volumes. Coupled to mass spectrometry (MS), it represents a powerful analytical technique providing (exact) mass information and enables molecular characterization based on fragmentation. Although hyphenation of CE and MS is not straightforward, much emphasis has been placed on enabling efficient ionization and user-friendly coupling. Though several interfaces are now commercially available, research on more efficient and robust interfacing with nano-electrospray ionization (ESI), matrix-assisted laser desorption/ionization (MALDI) and inductively coupled plasma mass spectrometry (ICP) continues with considerable results. At the same time, CE-MS has been used in many fields, predominantly for the analysis of proteins, peptides and metabolites. This review belongs to a series of regularly published articles, summarizing 248 articles covering the time between June 2016 and May 2018. Latest developments on hyphenation of CE with MS as well as instrumental developments such as two-dimensional separation systems with MS detection are mentioned. Furthermore, applications of various CE-modes including capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), capillary gel electrophoresis (CGE) and capillary isoelectric focusing (CIEF) coupled to MS in biological, pharmaceutical and environmental research are summarized.
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Affiliation(s)
| | - Kevin Jooß
- Faculty of Chemistry, Aalen University, Aalen, Germany.,Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, Neuherberg, Germany
| | - Oliver Höcker
- Faculty of Chemistry, Aalen University, Aalen, Germany.,Instrumental Analytical Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Jennifer Römer
- Faculty of Chemistry, Aalen University, Aalen, Germany.,Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany
| | - Johannes Schlecht
- Faculty of Chemistry, Aalen University, Aalen, Germany.,Department of Pharmaceutical/Medicinal Chemistry, Friedrich Schiller University, Jena, Germany
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25
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Konášová R, Koval D, Dytrtová JJ, Kašička V. Comparison of two low flow interfaces for measurement of mobilities and stability constants by affinity capillary electrophoresis–mass spectrometry. J Chromatogr A 2018; 1568:197-204. [DOI: 10.1016/j.chroma.2018.07.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 06/28/2018] [Accepted: 07/04/2018] [Indexed: 12/19/2022]
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26
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Prior A, van de Nieuwenhuijzen E, de Jong GJ, Somsen GW. Enantioselective micellar electrokinetic chromatography of dl-amino acids using (+)-1-(9-fluorenyl)-ethyl chloroformate derivatization and UV-induced fluorescence detection. J Sep Sci 2018; 41:2983-2992. [PMID: 29785784 PMCID: PMC6099287 DOI: 10.1002/jssc.201800204] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 05/11/2018] [Accepted: 05/16/2018] [Indexed: 01/24/2023]
Abstract
Chiral analysis of dl-amino acids was achieved by micellar electrokinetic chromatography coupled with UV-excited fluorescence detection. The fluorescent reagent (+)-1-(9-fluorenyl)ethyl chloroformate was employed as chiral amino acid derivatizing agent and sodium dodecyl sulfate served as pseudo-stationary phase for separating the formed amino acid diastereomers. Sensitive analysis of (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids was achieved applying a xenon-mercury lamp for ultraviolet excitation, and a spectrograph and charge-coupled device for wavelength-resolved emission detection. Applying signal integration over a 30 nm emission wavelength interval, signal-to-noise ratios for derivatized amino acids were up to 23 times higher as obtained using a standard photomultiplier for detection. The background electrolyte composition (electrolyte, pH, sodium dodecyl sulfate concentration, and organic solvent) was studied in order to attain optimal chemo- and enantioseparation. Enantioseparation of 12 proteinogenic dl-amino acids was achieved with chiral resolutions between 1.2 and 7.9, and detection limits for most derivatized amino acids in the 13-60 nM range (injected concentration). Linearity (coefficients of determination > 0.985) and peak-area and migration-time repeatabilities (relative standard deviations lower than 2.6 and 1.9%, respectively) were satisfactory. The employed fluorescence detection system provided up to 100-times better signal-to-noise ratios for (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids than ultraviolet absorbance detection, showing good potential for d-amino acid analysis.
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Affiliation(s)
- Amir Prior
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and SystemsVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Erik van de Nieuwenhuijzen
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and SystemsVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | | | - Govert W. Somsen
- Division of BioAnalytical Chemistry, Amsterdam Institute for Molecules, Medicines and SystemsVrije Universiteit AmsterdamAmsterdamThe Netherlands
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27
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Moldovan RC, Bodoki E, Servais AC, Chankvetadze B, Crommen J, Oprean R, Fillet M. Capillary electrophoresis-mass spectrometry of derivatized amino acids for targeted neurometabolomics - pH mediated reversal of diastereomer migration order. J Chromatogr A 2018; 1564:199-206. [PMID: 29910088 DOI: 10.1016/j.chroma.2018.06.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/02/2018] [Accepted: 06/06/2018] [Indexed: 01/08/2023]
Abstract
A targeted CE-MS approach was developed for the chiral analysis of biologically relevant amino acids in artificial cerebrospinal fluid (aCSF). In order to achieve chiral resolution, the five amino acids (Ser, Asn, Asp, Gln and Glu) were derivatized with (+)-1-(9-fluorenyl)ethyl chloroformate ((+)-FLEC). The diastereoselectivity was found to be highly dependent on pH for all analytes and the optimized background electrolyte (BGE) consisted of 150 mM acetic acid, adjusted to pH 3.7 with NH4OH. Furthermore, a reversal of the migration order of Asp derivatives was observed. This phenomenon seems to be caused by intra-molecular interactions affecting the pKa of the second ionizable group (the side chain carboxyl). The applicability of this method was evaluated using aCSF. A solid phase extraction (SPE) protocol was developed for the selective extraction of the FLEC derivatives. A full evaluation of the matrix effect and extraction yield was performed concluding that the matrix effect is marginal and the recoveries are between 46 and 92%. The method offers adequate sensitivity (limits of detection below 1 μM).
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Affiliation(s)
- Radu-Cristian Moldovan
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege, Avenue Hippocrate 15, B36, +3, Tower 4, 4000, Liege, Belgium; Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Haţieganu" University of Medicine and Pharmacy Cluj-Napoca, 4 Louis Pasteur street, 400349, Cluj-Napoca, Romania
| | - Ede Bodoki
- Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Haţieganu" University of Medicine and Pharmacy Cluj-Napoca, 4 Louis Pasteur street, 400349, Cluj-Napoca, Romania
| | - Anne-Catherine Servais
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege, Avenue Hippocrate 15, B36, +3, Tower 4, 4000, Liege, Belgium
| | - Bezhan Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi, Georgia
| | - Jacques Crommen
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege, Avenue Hippocrate 15, B36, +3, Tower 4, 4000, Liege, Belgium
| | - Radu Oprean
- Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Haţieganu" University of Medicine and Pharmacy Cluj-Napoca, 4 Louis Pasteur street, 400349, Cluj-Napoca, Romania
| | - Marianne Fillet
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege, Avenue Hippocrate 15, B36, +3, Tower 4, 4000, Liege, Belgium.
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28
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Chiral capillary electrophoresis with UV-excited fluorescence detection for the enantioselective analysis of 9-fluorenylmethoxycarbonyl-derivatized amino acids. Anal Bioanal Chem 2018; 410:4979-4990. [PMID: 29808298 PMCID: PMC6061710 DOI: 10.1007/s00216-018-1148-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/14/2018] [Accepted: 05/16/2018] [Indexed: 10/29/2022]
Abstract
The potential of capillary electrophoresis (CE) with ultraviolet (UV)-excited fluorescence detection for sensitive chiral analysis of amino acids (AAs) was investigated. DL-AAs were derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC)-Cl to allow their fluorescence detection and enhance enantioseparation. Fluorescence detection was achieved employing optical fibers, leading UV excitation light (< 300 nm) from a Xe-Hg lamp to the capillary window, and fluorescence emission to a spectrograph equipped with a charge-coupled device (CCD). Signal averaging over time and emission wavelength intervals was carried out to improve the signal-to-noise ratio of the FMOC-AAs. A background electrolyte (BGE) of 40 mM sodium tetraborate (pH 9.5), containing 15% isopropanol (v/v), 30 mM sodium dodecyl sulfate (SDS), and 30 mM β-cyclodextrin (β-CD), was found optimal for AA chemo- and enantioseparation. Enantioresolutions of 1.0 or higher were achieved for 16 proteinogenic DL-AAs. Limits of detection (LODs) were in the 10-100-nM range (injected concentration) for the D-AA enantiomers, except for FMOC-D-tryptophan (536 nM) which showed intramolecular fluorescence quenching. Linearity (R2 > 0.997) and repeatability for peak height (relative standard deviations (RSDs) < 7.0%; n = 5) and electrophoretic mobility (RSDs < 0.6%; n = 5) of individual AA enantiomers were established for chiral analysis of DL-AA mixtures. The applicability of the method was investigated by the analysis of cerebrospinal fluid (CSF). Next to L-AAs, endogenous levels of D-glutamine and D-aspartic acid could be measured in CSF revealing enantiomeric ratios of 0.35 and 19.6%, respectively. This indicates the method's potential for the analysis of low concentrations of D-AAs in presence of abundant L-AAs.
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29
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Zhang N, Tian M, Liu X, Yang L. Enzyme assay for d -amino acid oxidase using optically gated capillary electrophoresis-laser induced fluorescence detection. J Chromatogr A 2018; 1548:83-91. [DOI: 10.1016/j.chroma.2018.03.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/05/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
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30
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Voeten RLC, Ventouri IK, Haselberg R, Somsen GW. Capillary Electrophoresis: Trends and Recent Advances. Anal Chem 2018; 90:1464-1481. [PMID: 29298038 PMCID: PMC5994730 DOI: 10.1021/acs.analchem.8b00015] [Citation(s) in RCA: 187] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Robert L C Voeten
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.,TI-COAST , Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Iro K Ventouri
- TI-COAST , Science Park 904, 1098 XH Amsterdam, The Netherlands.,Analytical Chemistry Group, van't Hoff Institute for Molecular Sciences, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Rob Haselberg
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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31
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Stability and assessment of amino acids in parenteral nutrition solutions. J Pharm Biomed Anal 2018; 147:125-139. [DOI: 10.1016/j.jpba.2017.07.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/12/2017] [Accepted: 07/15/2017] [Indexed: 10/19/2022]
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32
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Crego AL, Mateos M, Nozal L. Recent contributions for improving sensitivity in chiral CE. Electrophoresis 2017; 39:67-81. [PMID: 28960403 DOI: 10.1002/elps.201700293] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/14/2017] [Accepted: 09/14/2017] [Indexed: 01/02/2023]
Abstract
The flexibility and versatility of the chiral CE are unrivaled and the same instrumentation can be used to separate a diverse range of analytes, both large and small molecules, whether charged or uncharged. However, one of the disadvantages is generally thought to be the poor sensitivity of ultraviolet (UV) detection, which is the most popular among CE detectors. This review focuses on methodologies and applications regarding improvements of sensitivity in chiral CE published in the last 2 years (June 2015 until May 2017). This contribution continues to update this series of biannual reviews, first published in Electrophoresis in 2006. The main body of the review brings a survey of publications organized according to different approaches to detect a low amount of analytes, either by sample treatment procedures or by in-capillary sample preconcentration techniques, both using UV detection, or even by employing detection systems more sensitive than UV absorption, such as LIF or MS. This review provides comprehensive tables listing the new approaches in sensitive chiral CE with categorizing by the fundamental mechanism to enhance the sensitivity, which provide relevant information on the strategies employed. The concluding remarks in the final part of the review evaluate present state of art and the trends for sensitivity enhancement in chiral CE.
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Affiliation(s)
- Antonio Luis Crego
- Department of Analytical Chemistry, Physical Chemistry, and Chemical Engineering, Faculty of Biology, Environmental Sciences, and Chemistry, University of Alcalá, Madrid, Spain
| | - María Mateos
- Institute of Applied Chemistry and Biotechnology, University of Alcalá, Madrid, Spain
| | - Leonor Nozal
- Institute of Applied Chemistry and Biotechnology, University of Alcalá, Madrid, Spain
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Moreno-González D, Haselberg R, Gámiz-Gracia L, García-Campaña AM, de Jong GJ, Somsen GW. Fully compatible and ultra-sensitive micellar electrokinetic chromatography-tandem mass spectrometry using sheathless porous-tip interfacing. J Chromatogr A 2017; 1524:283-289. [PMID: 28992989 DOI: 10.1016/j.chroma.2017.09.075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/26/2017] [Accepted: 09/30/2017] [Indexed: 11/26/2022]
Abstract
The on-line coupling of micellar electrokinetic chromatography and mass spectrometry (MEKC-MS) is often hampered by incompatibility problems leading to reduced separation performance and unfavorable limits of detection (LODs). Here we propose a new selective and highly sensitive MEKC-MS/MS method employing a sheathless porous-tip interface in combination with a micellar phase comprised of semi-volatile surfactant molecules. Carbamate pesticides (CRBs) were selected as representative model compounds being neutral toxic pollutants potentially present at trace levels in environmental water samples. A background electrolyte of 75mM perfluorooctanoic acid adjusted to pH 9.0 with ammonium hydroxide allowed efficient separation of 15 CRBs and appeared fully compatible with electrospray ionization (ESI)-MS. Interfacing parameters, such as the distance between the capillary tip and mass-spectrometer inlet, ESI voltage, and dry gas temperature and flow were optimized in order to attain good spray stability and high analyte signal-to-noise ratios. For CRBs the LODs ranged from 0.2 to 3.9ngL-1 (13nL injected, i.e., 2% of capillary volume), representing an improvement for certain CRBs of more than 300-fold when compared with conventional sheath-liquid interfacing. Good linearity (R2>0.99) and satisfactory reproducibility were obtained for all CRBs with interday RSD values for peak area and migration time of 4.0-11.3% and below 1.5%, respectively. Analysis of spiked mineral water showed that the new MEKC-MS/MS method allows selective and quantitative determination of CRB concentrations below the maximum residue limit of 100ngL-1 without the need for sample preconcentration.
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Affiliation(s)
- David Moreno-González
- Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Campus Fuentenueva, E-18071 Granada, Spain
| | - Rob Haselberg
- Division of BioAnalytical Chemistry, AIMMS research group BioMolecular Analysis, Faculty of Sciences, Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | - Laura Gámiz-Gracia
- Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Campus Fuentenueva, E-18071 Granada, Spain
| | - Ana M García-Campaña
- Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Campus Fuentenueva, E-18071 Granada, Spain
| | - Gerhardus J de Jong
- Biomolecular Analysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, AIMMS research group BioMolecular Analysis, Faculty of Sciences, Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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Poinsot V, Ong-Meang V, Ric A, Gavard P, Perquis L, Couderc F. Recent advances in amino acid analysis by capillary electromigration methods: June 2015-May 2017. Electrophoresis 2017; 39:190-208. [PMID: 28805963 DOI: 10.1002/elps.201700270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022]
Abstract
In the tenth edition of this article focused on recent advances in amino acid analysis using capillary electrophoresis, we describe the most important research articles published on this topic during the period from June 2015 to May 2017. This article follows the format of the previous articles published in Electrophoresis. The new developments in amino acid analysis with CE mainly describe improvements in CE associated with mass spectrometry. Focusing on applications, we mostly describe clinical works, although metabolomics studies are also very important. Finally, works focusing on amino acids in food and agricultural applications are also described.
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Affiliation(s)
- Véréna Poinsot
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | | | - Audrey Ric
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - Pierre Gavard
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - Lucie Perquis
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - François Couderc
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
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Wuethrich A, Quirino JP. Derivatisation for separation and detection in capillary electrophoresis (2015-2017). Electrophoresis 2017; 39:82-96. [PMID: 28758685 DOI: 10.1002/elps.201700252] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 02/01/2023]
Abstract
Derivatisation is an integrated part of many analytical workflows to enable separation and detection of the analytes. In CE, derivatisation is adapted in the four modes of pre-capillary, in-line, in-capillary, and post-capillary derivatisation. In this review, we discuss the progress in derivatisation from February 2015 to May 2017 from multiple points of view including sections about the derivatisation modes, derivatisation to improve the analyte separation and analyte detection. The advancements in derivatisation procedures, novel reagents, and applications are covered. A table summarising the 46 reviewed articles with information about analyte, sample, derivatisation route, CE method and method sensitivity is provided.
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Affiliation(s)
- Alain Wuethrich
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland, Brisbane, QLD, Australia
| | - Joselito P Quirino
- Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, TAS, Australia
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36
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Nie L, Dai Z, Ma S. Stereospecific Assay of (R)- and (S)-Goitrin in Commercial Formulation of Radix Isatidis by Reversed Phase High-Performance Liquid Chromatography. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2017; 2017:2810565. [PMID: 28894621 PMCID: PMC5574218 DOI: 10.1155/2017/2810565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/17/2017] [Indexed: 05/04/2023]
Abstract
Radix isatidis (Banlangen) is a widely used traditional Chinese medicine for treating fever and removing toxic heat. Pharmacological studies have indicated that (R)-goitrin (epigoitrin) is one of the main constituents accounting for its antiviral activity, while (S)-goitrin (goitrin) is known as an antithyroid factor. To better control the quality of radix isatidis and its formulations, it is imperative to enantiomerically determine the contents of R- and S-goitrin. In this study, an enantioselective method based on reversed phase chromatography was developed for the assay of (R, S)-goitrin enantiomers. Optimum separation was obtained on an S-Chiral A column (4.6 mm × 250 mm, 5 μm) using methanol/water (30 : 70, v/v) as the mobile phase. After validation, the method was applied to quantify the enantiomers in Banlangen granules, which is the most prescribed commercial formulation of radix isatidis. Compared to enantioselective resolution approaches based on normal phase chromatography, the new method could be conveniently performed using regular reversed phase high-performance liquid chromatography (RP-HPLC) equipment and was found to be more suitable for the enantioselective quality control of water-extracted and soluble medicines.
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Affiliation(s)
- Lixing Nie
- National Institutes for Food and Drug Control, China Food and Drug Administration, 2 Tiantan Xili, Beijing, China
| | - Zhong Dai
- National Institutes for Food and Drug Control, China Food and Drug Administration, 2 Tiantan Xili, Beijing, China
| | - Shuangcheng Ma
- National Institutes for Food and Drug Control, China Food and Drug Administration, 2 Tiantan Xili, Beijing, China
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Moldovan RC, Bodoki E, Servais AC, Crommen J, Oprean R, Fillet M. (+) or (-)-1-(9-fluorenyl)ethyl chloroformate as chiral derivatizing agent: A review. J Chromatogr A 2017; 1513:1-17. [PMID: 28756893 DOI: 10.1016/j.chroma.2017.07.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 07/10/2017] [Accepted: 07/12/2017] [Indexed: 11/25/2022]
Abstract
Over the last 30years, (±)-1-(9-fluorenyl)ethyl chloroformate ((±)-FLEC) was used as a chiral derivatizing agent in various analytical applications involving a wide range of endogenous, pharmaceutical and environmentally relevant molecules. This comprehensive review aims to present all the significant aspects related to the state of the art in FLEC labeling and subsequent chiral separation of the resulting diastereomers using LC, SFC and CE techniques.
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Affiliation(s)
- Radu-Cristian Moldovan
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege,Avenue Hippocrate 15, B36-+3-T4, 4000 Liege, Belgium; Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Hațieganu" University of Medicine and Pharmacy Cluj-Napoca,4 Louis Pasteur street, 400349 Cluj-Napoca, Romania
| | - Ede Bodoki
- Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Hațieganu" University of Medicine and Pharmacy Cluj-Napoca,4 Louis Pasteur street, 400349 Cluj-Napoca, Romania
| | - Anne-Catherine Servais
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege,Avenue Hippocrate 15, B36-+3-T4, 4000 Liege, Belgium
| | - Jacques Crommen
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege,Avenue Hippocrate 15, B36-+3-T4, 4000 Liege, Belgium
| | - Radu Oprean
- Department of Analytical Chemistry and Instrumental Analysis, Faculty of Pharmacy, "Iuliu Hațieganu" University of Medicine and Pharmacy Cluj-Napoca,4 Louis Pasteur street, 400349 Cluj-Napoca, Romania
| | - Marianne Fillet
- Laboratory for the Analysis of Medicines, Department of Pharmacy, Faculty of Medicine, CIRM, University of Liege,Avenue Hippocrate 15, B36-+3-T4, 4000 Liege, Belgium.
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