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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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2
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Xie SL, Junaid M, Bian WP, Luo JJ, Syed JH, Wang C, Xiong WX, Ma YB, Niu A, Yang XJ, Zou JX, Pei DS. Generation and application of a novel transgenic zebrafish line Tg(cyp1a:mCherry) as an in vivo assay to sensitively monitor PAHs and TCDD in the environment. JOURNAL OF HAZARDOUS MATERIALS 2018; 344:723-732. [PMID: 29154098 DOI: 10.1016/j.jhazmat.2017.11.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/24/2017] [Accepted: 11/12/2017] [Indexed: 02/06/2023]
Abstract
The polycyclic aromatic hydrocarbons (PAHs) and 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) are classified as human carcinogens, and can also cause serious health problems. To develop a convenient bio-monitoring tool for the detection of PAHs and TCDD in the environment, we generated a transgenic zebrafish line Tg(cyp1a:mCherry) with cyp1a promoter driving mCherry expression. Here, Tg(cyp1a:mCherry) embryos were treated with different concentrations of TCDD and five US EPA priority PAHs congeners. The results showed that the expressions of mCherry and endogenous cyp1a were consistent with the PAHs exposure concentrations and were largely induced by TCDD and ≥4-ring PAHs. Moreover, the sensitivity of Tg(cyp1a:mCherry) embryos was also evaluated through monitoring of the PAHs contamination in the water and soil samples. The elevated red fluorescent signals and cyp1a expression levels were observed in Tg(cyp1a:mCherry) zebrafish after exposure to water samples and soil organic extracts with higher concentrations of ≥4-ring PAHs. These results further strengthen our findings of concentration- and congener-dependent response of the newly established zebrafish. Taken together, the newly established zebrafish line will prove as a sensitive, efficient and convenient tool for monitoring PAHs and TCDD contamination in the environment.
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Affiliation(s)
- Shao-Lin Xie
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Muhammad Junaid
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wan-Ping Bian
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Juan-Juan Luo
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; Center for Neuroscience, Shantou University Medical College, Shantou 515041, China
| | - Jabir Hussain Syed
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Chao Wang
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Wen-Xu Xiong
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China
| | - Yan-Bo Ma
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Aping Niu
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Jun Yang
- Center for Neuroscience, Shantou University Medical College, Shantou 515041, China
| | - Ji-Xing Zou
- College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China.
| | - De-Sheng Pei
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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3
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Prior A, Sánchez-Hernández L, Sastre-Toraño J, Marina ML, de Jong GJ, Somsen GW. Enantioselective analysis of proteinogenic amino acids in cerebrospinal fluid by capillary electrophoresis-mass spectrometry. Electrophoresis 2016; 37:2410-9. [PMID: 27465690 DOI: 10.1002/elps.201600015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 06/06/2016] [Accepted: 06/15/2016] [Indexed: 11/06/2022]
Abstract
d-Amino acids (AAs) are increasingly being recognized as essential molecules in biological systems. Enantioselective analysis of proteinogenic AAs in biological samples was accomplished by CE-MS employing β-CD as chiral selector and ESI via sheath-liquid (SL) interfacing. Prior to analysis, AAs were fully derivatized with FMOC, improving AA-enantiomer separation and ESI efficiency. In order to optimize the separation and MS detection of FMOC-AAs, the effects of type and concentration of CD in the BGE, the composition of the SL, and MS-interfacing parameters were evaluated. Using a BGE of 10 mM β-CD in 50 mM ammonium bicarbonate (pH 8) containing 15% v/v isopropanol, a SL of isopropanol-water-1 M ammonium bicarbonate (50:50:1, v/v/v) at a flow rate of 3 μL/min, and a nebulizer gas pressure of 2 psi, 15 proteinogenic AAs could be detected with enantioresolutions up to 3.5 and detection limits down to 0.9 μM (equivalent to less than 3 pg AA injected). The selectivity of the method was demonstrated by the analysis of spiked cerebrospinal fluid, allowing specific detection of d-AAs. Repeatability and linearity obtained for cerebrospinal fluid were similar to standard solutions, with peak area and migration-time RSDs (n = 5) below 16.2 and 1.6%, respectively, and a linear response (R(2) ≥ 0.977) in the 3-90 μM range.
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Affiliation(s)
- Amir Prior
- Division of BioAnalytical Chemistry, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
| | - Laura Sánchez-Hernández
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - Javier Sastre-Toraño
- Division of Biomolecular Analysis, Utrecht University, CG Utrecht, The Netherlands
| | - Maria Luisa Marina
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - Gerhardus J de Jong
- Division of Biomolecular Analysis, Utrecht University, CG Utrecht, The Netherlands
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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Pérez-Fernández V, Dominguez-Vega E, Chankvetadze B, Crego AL, García MÁ, Marina ML. Evaluation of new cellulose-based chiral stationary phases Sepapak-2 and Sepapak-4 for the enantiomeric separation of pesticides by nano liquid chromatography and capillary electrochromatography. J Chromatogr A 2012; 1234:22-31. [DOI: 10.1016/j.chroma.2012.01.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/11/2012] [Accepted: 01/12/2012] [Indexed: 12/01/2022]
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5
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Koval D, Severa L, Adriaenssens L, Vávra J, Teplý F, Kašička V. Chiral analysis of helquats by capillary electrophoresis: Resolution of helical N-heteroaromatic dications using randomly sulfated cyclodextrins. Electrophoresis 2011; 32:2683-92. [DOI: 10.1002/elps.201100173] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/20/2011] [Accepted: 04/20/2011] [Indexed: 01/31/2023]
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6
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Chiral separation of agricultural fungicides. J Chromatogr A 2011; 1218:6561-82. [DOI: 10.1016/j.chroma.2011.07.084] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 07/21/2011] [Accepted: 07/26/2011] [Indexed: 11/18/2022]
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Abstract
This review article addresses the developments and applications of capillary electromigration methods coupled on-line with MS for chiral analysis. The multiple enantiomeric applications of this hyphenated technology are covered including chiral analysis of drugs, food compounds, pesticides, natural metabolites, etc. in different matrices such as plasma, urine, medicines, foods, etc. This work intends to provide an updated overview (including works published till September 2009) on the principal chiral applications carried out by CZE-MS, CEC-MS and MEKC-MS, discussing their main advantages and drawbacks in all their different areas of application as well as their foreseeable development in the not too distant future.
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Affiliation(s)
- Carolina Simó
- Department of Food Analysis, Institute of Industrial Fermentations (CSIC), Madrid, Spain
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8
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Herrero M, Simó C, García-Cañas V, Fanali S, Cifuentes A. Chiral capillary electrophoresis in food analysis. Electrophoresis 2010; 31:2106-14. [DOI: 10.1002/elps.200900770] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Pérez-Fernández V, García MÁ, Marina ML. Enantiomeric separation of cis-bifenthrin by CD-MEKC: Quantitative analysis in a commercial insecticide formulation. Electrophoresis 2010; 31:1533-9. [DOI: 10.1002/elps.200900718] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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Chen Y, Zhang J, Zhang L, Chen G. Separation of dipeptides with two chiral centers using 2-hydroxypropyl-β-CD-modified MEKC. Electrophoresis 2010; 31:1493-7. [DOI: 10.1002/elps.200900592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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11
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Characteristics and enantiomeric analysis of chiral pyrethroids. J Chromatogr A 2010; 1217:968-89. [DOI: 10.1016/j.chroma.2009.10.069] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 10/16/2009] [Accepted: 10/23/2009] [Indexed: 11/18/2022]
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12
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Giuffrida A, León C, García-Cañas V, Cucinotta V, Cifuentes A. Modified cyclodextrins for fast and sensitive chiral-capillary electrophoresis-mass spectrometry. Electrophoresis 2009; 30:1734-42. [DOI: 10.1002/elps.200800333] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Scriba GKEV. Cyclodextrins in capillary electrophoresis enantioseparations--recent developments and applications. J Sep Sci 2008; 31:1991-2011. [PMID: 18491357 DOI: 10.1002/jssc.200800095] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Capillary EKC has been established as a versatile and robust CE method for the separation of enantiomers. Within the chiral selectors added to the BGE CDs continue as the most widely used selectors due to their structural variety and commercial availability. This is reflected in the large number of practical applications of CDs to analytical enantioseparations that have been reported between January 2006 and January 2008, the period of time covered by this review. Most of these applications cover aspects of life sciences such as drug analysis, bioanalysis, environmental analysis, or food analysis. Moreover, new CD derivatives have been developed in an attempt to achieve altered enantioselectivities and to further broaden the application range. Finally, efforts will be summarized that aim at an understanding of the molecular level of the chiral recognition between CDs and the analytes.
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Affiliation(s)
- Gerhard K E V Scriba
- Department of Pharmaceutical Chemistry, School of Pharmacy, Friedrich Schiller University, Philosophenweg 14, D-07743 Jena, Germany.
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14
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Ali I, Gupta VK, Aboul-Enein HY. Chiral Resolution of Racemic Environmental Pollutants by Capillary Electrophoresis. Crit Rev Anal Chem 2008; 38:132-46. [DOI: 10.1080/10408340701804467] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Ghosh A, Dey J. Enantiomeric separations of binaphthyl derivatives by capillary electrophoresis usingN-(2-hydroxydodecyl)-L-threonine as chiral selector: Effect of organic additives. Electrophoresis 2008; 29:1540-7. [DOI: 10.1002/elps.200700638] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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García-Cañas V, Cifuentes A. Recent advances in the application of capillary electromigration methods for food analysis. Electrophoresis 2008; 29:294-309. [DOI: 10.1002/elps.200700438] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Dabek-Zlotorzynska E, Celo V, Yassine MM. Recent advances in CE and CEC of pollutants. Electrophoresis 2008; 29:310-23. [DOI: 10.1002/elps.200700510] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Sánchez-Hernández L, Crego AL, Marina ML, García-Ruiz C. Sensitive chiral analysis by CE: An update. Electrophoresis 2008; 29:237-51. [DOI: 10.1002/elps.200700531] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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19
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Herrero M, Ibáñez E, Fanali S, Cifuentes A. Quantitation of chiral amino acids from microalgae by MEKC and LIF detection. Electrophoresis 2007; 28:2701-9. [PMID: 17592610 DOI: 10.1002/elps.200600599] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this work, chiral and nonchiral MEKC methods have been combined with LIF detection (MEKC-LIF) to identify and quantify a group of D- and L-amino acids (D/L-aa) in different microalgae samples. The combination of the nonchiral and chiral-MEKC-LIF methods made the identification of the microalgae amino acids easier, previously derivatized with FITC, providing a double proof on the correct detection of these analytes. Three microalgae species, Spirulina platensis, Dunaliella salina, and Tetraselmis suecica, were compared in terms of their content in D-Arg, L-Arg, D-Lys, L-Lys, D-Ala, L-Ala, D-Glu, L-Glu, D-Asp, and L-Asp. Also, a comparison between two Spirulina platensis samples dried under different conditions (i.e., hot air or lyophilized) was carried out in order to investigate the effect of the thermal processing on the amino acid content. Moreover, two procedures for the extraction of amino acids from microalgae (i.e., a classical procedure and pressurized liquid extraction (PLE)) together with different conditions for amino acid derivatization were studied in order to increase the sensitivity of the whole analytical method. By using the selected chiral-MEKC-LIF conditions (100 mM sodium tetraborate, 30 mM SDS, and 20 mM beta-CD at pH 9.7) the main microalgae D/L-aa are separated in less than 25 min with efficiencies up to 840 000 plates/m and good sensitivity (i.e., 330 ng of D-Arg per gram of microalga could be detected by this procedure for an S/N of 3). Several D-aa were detected in all the microalgae, observing interesting differences in their D/L-aa profiles, what corroborates the usefulness of the chiral-MEKC-LIF approach to characterize different microalgae species as well as different microalgae drying processes. Moreover, the use of PLE can selectively extract different free amino acids from microalgae.
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Affiliation(s)
- Miguel Herrero
- Institute of Industrial Fermentations (CSIC), Madrid, Spain
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20
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Kahle KA, Foley JP. Review of aqueous chiral electrokinetic chromatography (EKC) with an emphasis on chiral microemulsion EKC. Electrophoresis 2007; 28:2503-26. [PMID: 17657766 DOI: 10.1002/elps.200600808] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The separation of enantiomers using electrokinetic chromatography (EKC) with chiral microemulsions is comprehensively reviewed through December 1, 2006. Aqueous chiral EKC separations based on other pseudostationary phases such as micelles and vesicles or on other chiral selectors such as CDs, crown ethers, glycopeptides, ligand exchange moeities are also reviewed from both mechanistic and applications perspective for the period of January 2005 to December 1, 2006.
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Affiliation(s)
- Kimberly A Kahle
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
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21
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Wang Z, Wang J, Hu Z, Kang J. Enantioseparation by CE with vancomycin as chiral selector: Improving the separation performance by dynamic coating of the capillary with poly(dimethylacrylamide). Electrophoresis 2007; 28:938-43. [PMID: 17309047 DOI: 10.1002/elps.200600514] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An approach for improving the separation performance of the enantioseparation by CE with vancomycin as chiral selector is described. In the present method, a solution of poly(dimethylacrylamide) (PDMA) was used for dynamic coating of the capillary wall to minimize the adsorption of vancomycin onto the capillary wall, and to depress the EOF. Compared with the bare fused-silica capillaries and the capillaries coated with the polycationic polymer hexadimethrine bromide (HDB), the PDMA-coated capillary displayed the best separation performance. The resulting coating could withstand hundreds of runs without losing its function. Moreover, a partial filling technique was applied to avoid interference in detection caused by the presence of vancomycin in the buffer. The separation time was shortened when a short-end-injection technique was applied. Several parameters such as buffer pH, vancomycin concentration and plug length of the vancomycin solution for the separation were optimized. Under the optimal conditions, all tested enantiomers, including FMOC amino acids derivatives, ketoprofen and fenoprofen, were baseline-separated in less than 4.2 min.
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Affiliation(s)
- Zhaoyan Wang
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China
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22
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Van Biesen G, Bottaro CS. Linear solvation energy relationships of anionic dimeric surfactants in micellar electrokinetic chromatography. J Chromatogr A 2007; 1157:437-45. [PMID: 17482628 DOI: 10.1016/j.chroma.2007.04.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 04/10/2007] [Accepted: 04/12/2007] [Indexed: 10/23/2022]
Abstract
The influence of the length of a flexible hydrophobic spacer on the selectivity of anionic dimeric surfactants was investigated. Disodium 1,omega-bis(decyloxymethyl)-dioxa alkane-1,omega disulfates with a spacer containing an ethylene, butylene, hexylene, octylene, decylene or dodecylene group were synthesized, and four of these were evaluated for use in micellar electrokinetic chromatography (MEKC) via linear solvation energy relationships (LSERs). There were no significant differences in the system constants of these surfactants, indicating that their micelles all have a very similar interface with the aqueous phase, regardless of the length of the hydrophobic spacer. Compared to sodium dodecylsulfate (SDS), these dimeric surfactants are slightly more cohesive, interact better with polarizable compounds, and are somewhat better hydrogen bond acceptors and worse hydrogen bond donors, while there is no difference in dipolarity. The critical micelle concentrations (CMCs) of these surfactants were in the order of 1mM, except for the dimeric surfactant with a spacer containing an ethylene group, which had a CMC <0.03 mM.
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Affiliation(s)
- Geert Van Biesen
- Memorial University of Newfoundland, Prince Philip Drive, Department of Chemistry, Chemistry/Physics Building Room 4000, St. John's, NFLD, Canada
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23
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Maier V, Petr J, Knob R, Horáková J, Sevcík J. Electrokinetic partial filling technique as a powerful tool for enantiomeric separation ofDL-lactic acid by CE with contactless conductivity detection. Electrophoresis 2007; 28:1815-22. [PMID: 17464963 DOI: 10.1002/elps.200600578] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A modified partial filling method for chiral separation of DL-lactic acid as the model chiral compound with vancomycin chloride as the chiral selector was developed by CE with contactless conductivity detection. Electrokinetic partial filling technique (EK-PFT) was used as an alternative method to the conventional hydrodynamic partial filling method. EK-PFT, in contrast to the hydrodynamic partial filling technique, allowed the removal of the chloride counterions from the chiral selector which otherwise led to poor sensitivity in conductivity detection. The baseline separation of DL-lactic acid as the model analyte was achieved in 5 min in a polyacrylamide-coated capillary. The best resolution was achieved by electrokinetic partial filling of vancomycin cations from the injection solution containing 5 mmol/L oxalate L-histidinium at pH 4.5 with 10 mmol/L vancomycin chloride. Computer simulation was used to explain the observed phenomena in the boundary between the inject vial and the capillary during the EK-PFT of vancomycin cations.
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Affiliation(s)
- Vítezslav Maier
- Department of Analytical Chemistry, Palacký University, Olomouc, Czech Republic.
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24
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Molina-Mayo C, Hernández-Borges J, Borges-Miquel TM, Rodríguez-Delgado MA. Determination of pesticides in wine using micellar electrokinetic chromatography with UV detection and sample stacking. J Chromatogr A 2007; 1150:348-55. [PMID: 16828783 DOI: 10.1016/j.chroma.2006.06.071] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 06/16/2006] [Accepted: 06/21/2006] [Indexed: 10/24/2022]
Abstract
In this work, the analysis of a group of four fungicides (pyrimethanil, nuarimol, procymidone and cyprodinil) and one insecticide (pirimicarb) by micellar electrokinetic chromatography (MEKC) with UV detection using the on-line preconcentration strategy called reversed electrode polarity stacking mode (REPSM) is proposed. After optimisation, an adequate separation electrolyte for the separation and stacking of these pesticides was obtained which consisted of 100 mM borate, 60 mM sodium dodecyl sulphate (SDS), at pH 9.0 and 2% 2-propanol. The use of this running buffer together with the REPSM preconcentration method provided limits of detection (LODs) between 38.3 and 241 microg/L. In order to apply the developed methodology for the analysis of these pesticides in wine samples, several off-line preconcentration strategies (mainly, solid-phase extraction, SPE, and solid-phase microextraction, SPME) were tested. Although the use of a SPE procedure, optimized in this work for water samples, using Oasis HLB cartridges, provided mean recovery values between 79 and 100% for spiked water samples, it could not be applied to the extraction of these pesticides from wine samples due to high interference from the sample matrix. However, the use of a SPME procedure using polydimethylsiloxane/divynilbenzene (PDMS/DVB) fibers allowed the selective extraction of four of the five pesticides which could be perfectly determined. The final combination of the off-line SPME and on-line REPSM preconcentration strategies allowed obtaining LODs between 17.6 and 32.3 microg/L.
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Affiliation(s)
- Carlos Molina-Mayo
- Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, Avda. Astrofísico Fco. Sánchez s/n, 38071 La Laguna, Tenerife, Canary Islands, Spain
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25
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Carlavilla D, Moreno-Arribas MV, Fanali S, Cifuentes A. Chiral MEKC-LIF of amino acids in foods: Analysis of vinegars. Electrophoresis 2006; 27:2551-7. [PMID: 16732620 DOI: 10.1002/elps.200500909] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The formation of D-amino acids (D-aa's) in many fermented foods depends, among other factors, on the particular fermentation conditions, the action and autolysis of the microorganisms involved. In this sense, the analysis of chiral amino acids is an interesting analytical strategy for food scientists, since these compounds can be used as bacterial markers and can help, e.g., to detect adulterations, microbiological contaminations, etc. In this work, a fast and sensitive method based on MEKC-LIF has been developed to analyze and quantitate L-amino acid (L-aa) and D-aa in vinegars. The chiral MEKC-LIF procedure uses 100 mM sodium tetraborate, 30 mM SDS, and 20 mM beta-CD at pH 9.7 as running buffer, obtaining a good separation of the main vinegar L-/D-aa previously derivatized with fluorescein isothiocianate. Namely, L/D proline, alanine, arginine, glutamic, and aspartic acid, plus the nonchiral amino acid gamma-aminobutyric acid are separated in less than 20 min with high efficiency (up to 720,000 plates/m) and good sensitivity (LODs lower than 16.6 nM were achieved). Several D-aa's were detected and quantified in balsamic, sherry, white wine, and cider vinegars using this MEKC-LIF procedure, observing interesting differences in their L-aa and D-aa profiles and contents.
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Affiliation(s)
- Davinia Carlavilla
- Department of Food Analysis, Institute of Industrial Fermentations (CSIC), Madrid, Spain
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Altria K, Marsh A, Sänger-van de Griend C. Capillary electrophoresis for the analysis of small-molecule pharmaceuticals. Electrophoresis 2006; 27:2263-82. [PMID: 16786477 DOI: 10.1002/elps.200600030] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper reviews the application of CE to the analysis of small-molecule pharmaceuticals. The areas of pharmaceutical analysis covered are enantiomer separation, the analysis of small molecules such as amino acids or drug counter-ions, pharmaceutical assay, determination of related substances and physicochemical measurements such as log P and pK(a) of compounds. The different electrophoretic modes available and their advantages for pharmaceutical analysis are described. Recent applications of CE for each subject area are tabulated with electrolyte details.
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Affiliation(s)
- Kevin Altria
- GlaxoSmithKline Research & Development, Harlow, Essex, UK.
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