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De Silva M, Dunn RC. Electric field-enhanced backscatter interferometry detection for capillary electrophoresis. Sci Rep 2024; 14:2110. [PMID: 38267528 PMCID: PMC10808210 DOI: 10.1038/s41598-024-52621-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 01/22/2024] [Indexed: 01/26/2024] Open
Abstract
Backscatter interferometry (BSI) is a refractive index (RI) detection method that is easily integrated with capillary electrophoresis (CE) and is capable of detecting species ranging from inorganic ions to proteins without additional labels or contrast agents. The BSI signal changes linearly with the square of the separation voltage which has been used to quantify sample injection, but has not been explored as a potential signal enhancement mechanism in CE. Here we develop a mathematical model that predicts a signal enhancement at high field strengths, where the BSI signal is dominated by the voltage dependent mechanism. This is confirmed in both simulation and experiment, which show that the analyte peak area grows linearly with separation voltage at high field strengths. This effect can be exploited by adjusting the background electrolyte (BGE) to increase the conductivity difference between the BGE and analyte zones, which is shown to improve BSI performance. We also show that this approach has utility in small bore capillaries where larger separation fields can be applied before excess Joule heating degrades the separation. Unlike other optical detection methods that generally degrade as the optical pathlength is reduced, the BSI signal-to-noise can improve in small bore capillaries as the larger separation fields enhance the signal.
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Affiliation(s)
- Miyuru De Silva
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047, USA
| | - Robert C Dunn
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047, USA.
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2
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Mwanza D, Phal S, Nyokong T, Tesfalidet S, Mashazi P. Electrografting of isophthalic acid monolayer and covalent attachment of antibody onto carbon surfaces: Construction of capacitive biosensor for methotrexate detection. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.139360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Chang YX, Zhang XM, Duan XC, Liu F, Du LM. Supramolecular interaction of methotrexate with cucurbit[7]uril and analytical application. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 183:131-137. [PMID: 28441540 DOI: 10.1016/j.saa.2017.04.060] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/19/2017] [Indexed: 06/07/2023]
Abstract
The supramolecular interaction between cucurbit[7]uril (CB[7]) as the host and the anti-cancer drug methotrexate (MTX) as the guest was studied using fluorescence spectroscopy, UV-visible absorption spectroscopy, 1H NMR, 2D NOESY, and theoretical calculations. The experimental results confirmed the formation of 1:2 inclusion complex with CB[7] and indicated a simple and sensitive competitive method for the fluorescence detection of MTX. It was found that the fluorescence intensities of CB[7]-palmatine, CB[7]-berberine and CB[7]-coptisine were quenched linearly upon the addition of MTX. The linear ranges obtained in the detection of MTX were 0.1-15μgmL-1, 0.2-15μgmL-1, and 0.4-15μgmL-1 with detection limits of 0.03μgmL-1, 0.06μgmL-1, and 0.13μgmL-1, respectively. This method can be used for the determination of MTX in biological fluids. These results suggested that cucurbit[7]uril is a promising drug carrier for targeted MTX delivery and monitoring, with improved efficacy and reduced toxicity in normal tissues.
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Affiliation(s)
- Yin-Xia Chang
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, PR China.
| | - Xiang-Mei Zhang
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, PR China
| | - Xue-Chao Duan
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, PR China
| | - Fan Liu
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, PR China
| | - Li-Ming Du
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, PR China.
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4
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Khadem Sadigh M, Zakerhamidi MS, Seyed Ahmadian SM, Johari-Ahar M, Zare Haghighi L. Environment effect on spectral and charge distribution characteristics of some drugs of folate derivatives. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 171:10-17. [PMID: 27458760 DOI: 10.1016/j.saa.2016.07.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 07/16/2016] [Accepted: 07/19/2016] [Indexed: 06/06/2023]
Abstract
Molecular surrounding media as an important factor can effect on the operation of wide variety of drugs. For more study in this paper, spectral properties of Methotrexate and Folinic acid have been studied in various solvents. Our results show that the photo-physical of solute molecules depend strongly on solute-solvent interactions and active groups in their chemical structures. In order to investigate the contribution of specific and nonspecific interactions on the various properties of drug molecules, the linear solvation energy relationships concept is used. Moreover, charge distribution characteristics of used samples with various resonance structures in solvent environments were calculated by means of solvatochromic method. The high value of dipole moments in excited state show that local intramolecular charge transfer can occur by excitation. These results about molecular interactions can be extended to biological systems and can indicate completely the behaviors of Methotrexate and Folinic acid in polar solvents such as water in body system.
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Affiliation(s)
- M Khadem Sadigh
- Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz, Iran.
| | - M S Zakerhamidi
- Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz, Iran
| | - S M Seyed Ahmadian
- Department of Chemistry, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - M Johari-Ahar
- Department of Medicinal Chemistry, School of Pharmacy, Ardabil University of Medical Sciences (ArUMS), Ardabil, Iran
| | - L Zare Haghighi
- Department of Chemistry, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran
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Sanjay S, Girish C. Role of miRNA and its potential as a novel diagnostic biomarker in drug-induced liver injury. Eur J Clin Pharmacol 2016; 73:399-407. [PMID: 28028586 DOI: 10.1007/s00228-016-2183-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022]
Abstract
PURPOSE MicroRNAs (miRNA or miR) are the most abundant and stable class of small RNA. Unlike the typical RNA molecules present in the cell, they do not encode proteins but can control translation. and Hhence, they are found to play a major role in the regulation of cellular processes. miRNAs have been shown to differentially regulate various genes, and the expression levels of some miRNAs changes several fold in liver and serum, during drug- induced toxicity. This review summarises some of the latest findings about the biological functions of miRNA and its potential use as diagnostic biomarkers in drug- induced liver injury. METHODS The information presented in this article is taken from published literature, both original work and reviews on mechanisms of drug- induced liver injury, miRNA in liver pathophysiology, and studies exploring the use of miRNA as biomarker in drug- induced liver injury. Literature search was done using search engines:- PUBMED, Google scholar, and relevant journal sites. RESULTS AND CONCLUSIONS Recent research provides insight into the ability of miRNA to regulate various pathways in diseased and nondiseased states of liver. They also lay a foundation for development of diagnostic tests utilizing the potential of miRNAs that can not only be used for early detection of DILI but also to differentiate between different types of DILI. More studies on biological functions of miRNA and standardisation of protocol between research laboratories can lead to further advancement in this field. Considering the therapeutic and diagnostic potential of miRNA, the major challenge would be to integrate these findings to clinical settings where it can be used for the treatment of cases with DILI.
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Affiliation(s)
- Sukumaran Sanjay
- Department of Pharmacology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India
| | - Chandrashekaran Girish
- Department of Pharmacology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India.
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A sandwich substrate for ultrasensitive and label-free SERS spectroscopic detection of folic acid / methotrexate. Biomed Microdevices 2015; 16:673-9. [PMID: 24850231 DOI: 10.1007/s10544-014-9871-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A highly sensitive surface enhanced Raman scattering (SERS) substrate with particle-film sandwich geometry has been developed for the label free detection of folic acid (FA) and methotrexate (MTX). In this sandwich structure, the bottom layer is composed of a copper foil decorated with silver nanoparticles synthesized by the galvanic displacement reaction, and top layer is constituted by silver nanoparticles. The FA and MTX molecules are sandwiched between the silver nanoparticles decorated copper film and the silver nanoparticles. The plasmonic coupling between the two layers of the sandwich structure greatly enhances the SERS spectra of FA and MTX. SERS activity of the substrate was studied and optimized by adjusting the time of galvanic displacement reaction. The SERS spectra of the FA and MTX showed the minimum detection concentration of 100 pM. The identification of methotrexate and folic acid analogs was also carried out by SERS spectra analysis.
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Abd El-Hady D, Albishri HM, Rengarajan R. Eco-friendly ionic liquid assisted capillary electrophoresis andα-acid glycoprotein-assisted liquid chromatography for simultaneous determination of anticancer drugs in human fluids. Biomed Chromatogr 2014; 29:925-34. [DOI: 10.1002/bmc.3376] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/12/2014] [Accepted: 10/03/2014] [Indexed: 01/24/2023]
Affiliation(s)
- Deia Abd El-Hady
- Chemistry Department, Faculty of Science-North Jeddah; King Abdulaziz University; 80203 Jeddah Saudi Arabia
- Chemistry Department, Faculty of Science; Assiut University; 71516 Assiut Egypt
| | - Hassan M. Albishri
- Chemistry Department, Faculty of Science; King Abdulaziz University; 80203 Jeddah Saudi Arabia
| | - Rajesh Rengarajan
- Chemistry Department, Faculty of Science; King Abdulaziz University; 80203 Jeddah Saudi Arabia
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Analysis of anticancer drugs: a review. Talanta 2011; 85:2265-89. [PMID: 21962644 DOI: 10.1016/j.talanta.2011.08.034] [Citation(s) in RCA: 316] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/15/2011] [Accepted: 08/16/2011] [Indexed: 01/05/2023]
Abstract
In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.
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Quenched phosphorescence as alternative detection mode in the chiral separation of methotrexate by electrokinetic chromatography. Anal Bioanal Chem 2011; 400:2913-9. [PMID: 21499966 PMCID: PMC3102850 DOI: 10.1007/s00216-011-4991-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Revised: 03/28/2011] [Accepted: 04/06/2011] [Indexed: 10/28/2022]
Abstract
Quenched phosphorescence was used, for the first time, as detection mode in the chiral separation of methotrexate (MTX) enantiomers by electrokinetic chromatography. The detection is based on dynamic quenching of the strong emission of the phosphorophore 1-bromo-4-naphthalene sulfonic acid (BrNS) by MTX under deoxygenated conditions. The use of a background electrolyte with 3 mg/mL 2-hydroxypropyl-β-cyclodextrin and 20% MeOH in 25 mM phosphate buffer (pH 7.0) and an applied voltage of 30 kV allowed the separation of L-MTX and its enantiomeric impurity D-MTX with sufficient resolution. In the presence of 1 mM BrNS, a detection limit of 3.2 × 10(-7) M was achieved, about an order of magnitude better than published techniques based on UV absorption. The potential of the method was demonstrated with a degradation study and an enantiomeric purity assessment of L-MTX. Furthermore, L-MTX was determined in a cell culture extract as a proof-of-principle experiment to show the applicability of the method to biological samples.
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Bioanalytical method development for a generation 5 polyamidoamine folic acid methotrexate conjugated nanoparticle. Anal Bioanal Chem 2010; 397:1841-52. [DOI: 10.1007/s00216-010-3716-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/29/2010] [Accepted: 03/31/2010] [Indexed: 10/19/2022]
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Cai C, Chen X, Gong H. Interaction of anticancer drug methotrexate with nucleic acids analyzed by multi-spectroscopic method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2009; 72:46-49. [PMID: 19010712 DOI: 10.1016/j.saa.2008.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2007] [Revised: 07/16/2008] [Accepted: 07/17/2008] [Indexed: 05/27/2023]
Abstract
Methotrexate (MTX) as an antifolate, which is widely used as chemotherapeutic drugs. A high-dose MTX therapy has a direct toxicity influence on the non-germinal cells, especially the liver cells. It is known that the inject dose for adults is 10-30 mg and is half for children for routine use, while our experiments showed that the optimum dosage of MTX which enhanced the RLS intensities to the maximum is 4.54 ng ml(-1). The interaction of methotrexate (MTX) with nucleic acids in aqueous solution in the presence of cetyltrimethylammonium bromide (CTMAB), a kind of cationic surfactant similar to the Human cells, were investigated based on the measurements of resonance light scattering (RLS), UV-vis, fluorescence and NMR spectra, etc. The interaction has been proved to give a ternary complex of MTX-CTMAB-DNA in BR buffer (pH 9.30), which exhibits strong enhanced RLS signals at 339.5 nm.
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Affiliation(s)
- Changqun Cai
- Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, PR China.
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12
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Altria KD, Filbey SD. Quantitative Pharmaceutical Analysis by Capillary Electrophoresis. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10826079308020985] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Schaller D, Hilder EF, Haddad PR. Separation of antidepressants by capillary electrophoresis with in-line solid-phase extraction using a novel monolithic adsorbent. Anal Chim Acta 2005; 556:104-11. [PMID: 17723335 DOI: 10.1016/j.aca.2005.07.035] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2005] [Revised: 07/19/2005] [Accepted: 07/21/2005] [Indexed: 11/24/2022]
Abstract
The separation of three selective serotonin reuptake inhibitors (SSRIs) by capillary electrophoresis (CE) with fully integrated solid-phase extraction (SPE) is described. Polymeric monolithic SPE modules were prepared in situ within a fused silica capillary from either butyl methacrylate-co-ethylene dimethacrylate or 3-sulfopropyl methacrylate-co-butyl methacrylate-co-ethylene dimethacrylate. Using a 1cm SPE module placed at the inlet of the capillary, a mixture of sertraline, fluoxetine and fluvoxamine was extracted from aqueous solution by applying a simple pressure rinse. Under pressure-driven conditions, efficient elution was possible from both SPE materials investigated using 50mM phosphate buffer, pH 3.5 in acetonitrile (20/80, v/v). Two different strategies were investigated for the efficient elution and subsequent CE separation. Injection of an aqueous sample plug directly into the non-aqueous elution/separation buffer was found to be unsuitable with poor elution profiles observed in the electrodriven mode. Alternatively, a sample plug equivalent to several capillary volumes could be injected by pressure followed by filling the capillary with the non-aqueous elution/separation buffer from the outlet end using a combination of pressure and electrodriven flow. Using a neutral monolith, efficient elution/separation was not possible due to an unstable electroosmotic flow (EOF), however, by adding the ionisable monomer, 3-sulfopropyl methacrylate to the SPE module to increase and stabilise the EOF, it was possible to achieve efficient elution from the SPE module, followed by baseline separation by CE using a 200 mM acetate buffer, pH 3.5 in acetonitrile (10/90, v/v). With enrichment factors of over 500 achieved for each of the analytes this demonstrates the potential of in-line SPE-CE for the sensitive analysis of these drugs.
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Affiliation(s)
- David Schaller
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, University of Tasmania, Private Bag 75, Hobart 7001, Tasmania, Australia
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Rodríguez Flores J, Berzas Nevado JJ, Durán Merás I, Rodríguez Gómez MJ. Capillary electrophoretic determination of triamterene, methotrexate, and creatinine in human urine. J Sep Sci 2005; 28:658-64. [PMID: 15912736 DOI: 10.1002/jssc.200400059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A capillary zone electrophoresis (CZE) method using a fused-silica capillary (60.2 cm x 75 microm ID) was investigated for the determination of triamterene (TRI), methotrexate (MTX), and creatinine (CREA) in human urine. The separation was performed using a hydrodynamic injection time of 7 s (0.5 psi), a voltage of 25 kV, a capillary temperature of 30 degrees C, and 40 mM phosphoric acid adjusted to pH 2.25 by addition of triethanolamine as separation electrolyte. Under these conditions, analysis takes about 15 min. A linear response over the 0.5-15.0 mg L(-1) concentration range was found for TRI and MTX, and 0.5-80.0 mg L(-1) for CREA. Dilution of the sample (water:urine, 1:1 for TRI and MTX, and 1:25 for CREA determination) was the only step necessary prior to analysis by electrophoresis. The developed method is easy, rapid, and sensitive and has been applied to determine triamterene,methotrexate, and creatinine in urine samples with satisfactory results.
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Affiliation(s)
- Juana Rodríguez Flores
- Department of Analytical Chemistry and Foods Technology, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
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Rodríguez Flores J, Peñalvo GC, Mansilla AE, Gómez MJR. Capillary electrophoretic determination of methotrexate, leucovorin and folic acid in human urine. J Chromatogr B Analyt Technol Biomed Life Sci 2005; 819:141-7. [PMID: 15797531 DOI: 10.1016/j.jchromb.2005.01.039] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
A simple, rapid and sensitive procedure using capillary zone electrophoresis (CZE) to measure methotrexate, folinic acid and folic acid in human urine has been developed and validated. Optimum separation of methotrexate, folinic acid and folic acid was obtained on a 60 cm x 75 microm capillary using a 15 mM phosphate buffer solution (pH 12.0), temperature and voltage 20 degrees C and 25 kV, respectively and hydrodynamic injection. Under these conditions the analysis takes approximately 9.0 min. Good results were obtained for different aspects including stability of the solutions, linearity, accuracy and precision. Before CZE determination, the urine samples were purified and enriched by means of a solid phase extraction step with a preconditioned C(18) cartridge and eluting the compound with a mixture 1:1 of methanol:water. A linear response over the urine concentration range 1.0-6.0 mgL(-1) for MTX and 0.5-6.0 mgL(-1) for folinic acid and folic acid was observed. Detection limits for the three compound in urine were 0.35 mgL(-1). CZE was shown to be a good method with regard to simplicity, satisfactory precision, and sensitivity.
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Affiliation(s)
- J Rodríguez Flores
- Department of Analytical Chemistry and Foods Technology, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
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Bhoopathy S, Karnes HT. Determination of (3S)-3-hydroxy quinidine for metabolism screening experiments using direct injection capillary electrophoresis and laser-induced fluorescence detection. Biomed Chromatogr 2002; 16:1-6. [PMID: 11816004 DOI: 10.1002/bmc.100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Capillary electrophoresis (CE) has been used with collinear laser-induced fluorescence detection (LIF) to determine the amount of (3S)-3-hydroxy quinidine (3OHQ) formed on direct injection of microsomal incubation mixtures. 3OHQ is the CYP 3A4 metabolite of quinidine sulfate (QS) and is therefore useful for metabolism screening studies. The method was validated analytically and tested for its capability of screening for a weak inhibitor of the CYP 3A4 isozyme. A linear calibration was found to provide the best fit for the standard curve with a correlation of 0.9950 and all concentration residuals less than 15%. The percentage relative standard deviations (RSDs) of two controls, 175 and 2250 ng/mL, were 9.29 and 5.68% and the percentage differences from normal (DFN) were 6.87 and -4.37%, respectively. The concentration limit of detection (LOD) for 3OHQ in the incubation matrix was 52.11ng/mL and the mass LOD was approximately 521.1 fg (injection volume 10 nL). The effectiveness of the method to screen for the weak inhibitor erythromycin has been shown by calculating percentage inhibition when incubating with different concentrations of QS. Sensitive detection coupled with the convenience of the direct injection technique makes this an attractive approach for metabolism screening. The small sample size capability of CE will further reduce the quantities of probe drug, microsomes and other reagents required for incubation studies.
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Affiliation(s)
- S Bhoopathy
- Department of Pharmaceutics, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298-0533, USA
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Páez X, Hernández L. Biomedical applications of capillary electrophoresis with laser-induced fluorescence detection. Biopharm Drug Dispos 2001; 22:273-89. [PMID: 11835251 DOI: 10.1002/bdd.277] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Capillary electrophoresis (CE) is a high-efficiency analytical technique that has had a great impact as a tool in biomedical research, clinical and forensic practice in the last ten years. Only in one of the applications, the DNA analysis, it has had an explosive exponential growth in the last few years. This impact is expressed in an enormous amount of CE articles and many reviews. The CE advantages with respect to other analytical techniques: the required very small sample volume, rapid analysis, great resolution power and low costs, have made this technique ideal for the analysis of a numerous endogenous and exogenous substances present in biological fluids. The different modes of CE have been coupled to different detection techniques such as UV-absorbance, electrochemical, mass spectrometry and laser-induced fluorescence detection (LIFD) to detect different nature and molecular size separated analytes. This review focuses mostly on the applications of CE-LIFD, to measure drugs and endogenous neuroactive substances such as amino acids and monoamines, especially in microdialysis samples from experimental animals and humans. CE-LIFD trends are discussed: automated faster analysis with capillary array systems, resolution power improvement, higher detection sensitivity, and CE systems miniaturization for extremely small sample volume, in order to make CE easier and affordable to the lab bench or the clinical bed.
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Affiliation(s)
- X Páez
- Laboratory of Behavioral Physiology, Universidad de los Andes, Mérida, Venezuela.
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Abstract
One of the weak points of capillary electrophoresis is the need to implement rigorously sample pretreatment because its great impact on the quality of the qualitative and quantitative results provided. One of the approaches to solve this problem is through the symbiosis of automatic continuous flow systems (CFSs) and capillary electrophoresis (CE). In this review a systematic approach to CFS-CE coupling is presented and discussed. The design of the corresponding interface depends on three factors, namely: (a) the characteristics of the CFS involved which can be non-chromatographic and chromatographic; (b) the type of CE equipment: laboratory-made or commercially available; and (c) the type of connection which can be in-line (on-capillary), on-line or mixed off/on-line. These are the basic criteria to qualify the hyphenation of CFS (solid-phase extraction, dialysis, gas diffusion, evaporation, direct leaching) with CE described so far and applied to determine a variety of analytes in many different types of samples. A critical discussion allows one to demonstrate that this symbiosis is an important topic in research and development, besides separation and detection, to consolidate CE as a routine analytical tool.
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Affiliation(s)
- M Valcárcel
- Analytical Chemistry Division, University of Córdoba, Spain.
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Palmer J, Burgi DS, Munro NJ, Landers JP. Electrokinetic injection for stacking neutral analytes in capillary and microchip electrophoresis. Anal Chem 2001; 73:725-31. [PMID: 11248884 DOI: 10.1021/ac001046d] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An on-column mechanism for electrokinetically injecting long sample plugs with simultaneous stacking of neutral analytes in capillary electrokinetic chromatography is presented. On-column stacking methods allow for the direct injection of long sample plugs into the capillary, with narrowing of the analyte peak width to allow for an increase in the detected signal. Low-pressure injections (approximately 50 mbar) are commonly used to introduce sample plugs containing neutral analytes. We demonstrate that injection can be accomplished by applying an electric field from the sample vial directly into the capillary, with neutral analytes injected by electroosmotic flow at up to 1 order of magnitude faster than the corresponding pressure injections. Since stacking occurs simultaneously with electrokinetic injection, stacking is initiated at the capillary inlet, resulting in an increased length of capillary remaining for separation. Reproducibility obtained for peak height and peak area with electroosmotic flow injection is comparable to that obtained with the pressure injection mode, while reproducibility of analysis time is markedly improved. Electrokinetic stacking of neutral analytes utilizing electroosmotic flow is demonstrated with discontinuous (high conductivity, high mobility) as well as continuous (equal conductivity, equal mobility) sample electrolytes. Injecting neutral analytes by electroosmotic flow affords a 10-fold or greater decrease in analysis times when capillaries of 50-microm i.d. or smaller are used. This stacking method should be exportable to dynamic pH junction stacking and electrokinetic chromatography with capillary arrays. Equations describing this electrokinetic injection mode are introduced and stacking of a neutral analyte on a microchip by electrokinetic injection using a simple cross-T channel configuration is demonstrated.
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Affiliation(s)
- J Palmer
- Department of Chemistry, University of Virginia, Charlottesville 22901, USA
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Abstract
Capillary electrophoresis (CE) is a useful method to quantify drugs in biological fluids. However, especially for blood or plasma samples, the sensitivity is not sufficient to quantify drugs and their metabolites as they often need to be quantified in the lower microg/L range. To overcome this limitation and to increase the sensitivity, two strategies are applied: first, to increase the amount of analyte added to the capillary and, second, to increase the sensitivity on the detector site. To improve the sensitivity on the detector site, alternative detection techniques to UV detection, e.g., laser-induced fluorescence detection (LIF) or mass spectroscopy (MS), can be applied. However, LIF detection can only be used for fluorescent analytes and the current equipment for CE-MS coupling provides only small improvements in sensitivity compared to UV detection. The detection window for UV detection can be enhanced using capillaries with an extended light path (bubble cell) or Z-shaped capillaries. Sensitivity improvements up to a factor of 10 have been reported. Increasing the amount of analyte in the capillary can be done either by chromatographic or by electrokinetic methods. Chromatographic methods such as on-capillary membrane preconcentration have been used for several analytes. However, no validated application has been reported to date. In contrast, several validated examples can be found in which electrokinetic techniques like sample stacking have been applied to achieve limits of quantification in the lower microg/L range. In conclusion, to date, electrokinetic techniques such as field-amplified sample injection offer the most promising results in achieving a sufficient sensitivity to quantify drugs in biological fluids.
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Affiliation(s)
- G Hempel
- Institut für Pharmazeutische, Chemie der Universität, Münster, Germany.
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23
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Lobo ED, Balthasar JP. Highly sensitive high-performance liquid chromatographic assay for methotrexate in the presence and absence of anti-methotrexate antibody fragments in rat and mouse plasma. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 736:191-9. [PMID: 10676999 DOI: 10.1016/s0378-4347(99)00460-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Recently, Balthasar and Fung have proposed that anti-methotrexate antibody fragments may be employed to enhance the selectivity of intraperitoneal methotrexate (MTX) therapy. This current work presents a sensitive high-performance liquid chromatographic method for measuring plasma concentrations of total (i.e., bound and unbound) MTX and free (unbound) MTX in rat and mouse plasma, in the presence or absence of therapeutic anti-MTX antibody fragments. The assay involves pre-column derivatization of MTX by sodium hydrosulfite to 2,4-diamino-6-methylpteridine. The limit of quantitation for MTX by this assay was 1.25 ng in rat plasma, mouse plasma and mouse plasma ultrafiltrate, which corresponds to a concentration of 25 ng/ml for a 50 microl sample. The limit of quantitation was found to be 2.5 ng in rat plasma ultrafiltrate (i.e., 50 ng/ml in 50 microl rat plasma ultrafiltrate). The method was shown to be quite accurate, as the mean assayed concentration of quality control samples was within 10% of theoretical values. We have applied the method to the investigation of MTX pharmacokinetics in mice and rats, following the administration of MTX alone or following simultaneous administration of MTX and anti-MTX Fab fragments. The method has been shown to be suitable for the assay of total and free methotrexate in the plasma of these species and will enable the testing of pharmacokinetic hypotheses regarding the influence of anti-MTX Fab fragments on the disposition of MTX.
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Affiliation(s)
- E D Lobo
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City 84108, USA
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24
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Veraart JR, Lingeman H, Brinkman UA. Coupling of biological sample handling and capillary electrophoresis. J Chromatogr A 1999; 856:483-514. [PMID: 10526801 DOI: 10.1016/s0021-9673(99)00588-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The analysis of biological samples (e.g., blood, urine, saliva, tissue homogenates) by capillary electrophoresis (CE) requires efficient sample preparation (i.e., concentration and clean-up) procedures to remove interfering solutes (endogenous/exogenous and/or low-/high-molecular-mass), (in)organic salts and particulate matter. The sample preparation modules can be coupled with CE either off-line (manual), at-line (robotic interface), on-line (coupling via a transfer line) or in-line (complete integration between sample preparation and separation system). Sample preparation systems reported in the literature are based on chromatographic, electrophoretic or membrane-based procedures. The combination of automated sample preparation and CE is especially useful if complex samples have to be analyzed and helps to improve both selectivity and sensitivity. In this review, the different modes of solid-phase (micro-) extraction will be discussed and an overview of the potential of chromatographic, electrophoretic (e.g., isotachophoresis, sample stacking) and membrane-based procedures will be given.
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Affiliation(s)
- J R Veraart
- Vrije Universiteit, Department of Analytical Chemistry and Applied Spectroscopy, Amsterdam, The Netherlands.
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25
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Boone CM, Waterval JC, Lingeman H, Ensing K, Underberg WJ. Capillary electrophoresis as a versatile tool for the bioanalysis of drugs--a review. J Pharm Biomed Anal 1999; 20:831-63. [PMID: 10746954 DOI: 10.1016/s0731-7085(99)00088-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This review article presents an overview of current research on the use of capillary electrophoretic techniques for the analysis of drugs in biological matrices. The principles of capillary electrophoresis and its various separation and detection modes are briefly discussed. Sample pretreatment methods which have been used for clean-up and concentration are discussed. Finally, an extensive overview of bioanalytical applications is presented. The bioanalyses of more than 200 drugs have been summarised, including the applied sample pretreatment methods and the achieved detection limits.
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Affiliation(s)
- C M Boone
- Department of Analytical Chemistry and Toxicology, University Center for Pharmacy, Groningen, The Netherlands.
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26
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Samcová E, Kvasnicová V, Urban J, Jelínek I, Coufal P. Determination of thiodiglycolic acid in urine by capillary electrophoresis. J Chromatogr A 1999; 847:135-9. [PMID: 10431357 DOI: 10.1016/s0021-9673(98)01034-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A sensitive capillary electrophoretic method was developed for the determination of thiodiglycolic acid (TDA) in urine which avoids the pretreatment of the urine sample. Several carrier electrolytes were examined. The most suitable carrier electrolyte system consisted of potassium hydrogen phthalate (5 mM), 2-(N-morpholino)ethanesulfonic acid (50 mM) and tetradecyltrimethylammonium bromide (0.5 mM), pH 5.2. Ten times diluted fresh midstream void urine was used for the determination. In this way, the concentrations of TDA between 5 and 50 mg/l in undiluted urine samples can be determined.
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Affiliation(s)
- E Samcová
- Department of Medical Chemistry and Toxicology, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
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27
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McCrudden EA, Tett SE. Improved high-performance liquid chromatography determination of methotrexate and its major metabolite in plasma using a poly(styrene-divinylbenzene) column. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 721:87-92. [PMID: 10027640 DOI: 10.1016/s0378-4347(98)00439-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A sensitive high-performance liquid chromatographic assay has been developed for measuring plasma concentrations of methotrexate and its major metabolite, 7-hydroxymethotrexate. Methotrexate and metabolite were extracted from plasma using solid-phase extraction. An internal standard, aminopterin was used. Chromatographic separation was achieved using a 15-cm poly(styrene-divinylbenzene) (PRP-1) column. This column is more robust than a silica-based stationary phase. Post column, the eluent was irradiated with UV light, producing fluorescent photolytic degradation products of methotrexate and the metabolite. The excitation and emission wavelengths of fluorescence detection were at 350 and 435 nm, respectively. The mobile phase consisted of 0.1 M phosphate buffer (pH 6.5), with 6% N,N-dimethylformamide and 0.2% of 30% hydrogen peroxide. The absolute recoveries for methotrexate and 7-hydroxymethotrexate were greater than 86%. Precision, expressed as a coefficient of variation (n=6), was <10% at each of five methotrexate concentrations in the range 2.5-50 ng/ml. The limits of quantitation of methotrexate were 1 and 2.5 ng/ml for methotrexate and 7-hydroxymethotrexate, respectively (using 1 ml plasma). A robust HPLC method has been developed for the reproducible quantitation of methotrexate in plasma of patients taking a weekly dose of methotrexate for rheumatoid arthritis.
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Affiliation(s)
- E A McCrudden
- Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Darlinghurst, NSW, Australia
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28
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Veraart JR, Gooijer C, Lingeman H, Velthorst NH, Brinkman UA. At-line solid-phase extraction for capillary electrophoresis: application to negatively charged solutes. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1998; 719:199-208. [PMID: 9869380 DOI: 10.1016/s0378-4347(98)00410-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The analysis of complex biological samples with capillary electrophoresis (CE) requires proper sample pretreatment. In this paper the applicability of solid-phase extraction (SPE) coupled at-line with CE is studied, by using a laboratory-made interface. A fresh (disposable) SPE cartridge is used for each sample to prevent carry-over effects. The sample handling procedure is performed parallel with the analysis of the previous sample, to improve sample throughput. Using this set-up, negatively charged test compounds (some non-steroid anti-inflammatory drugs) can be determined in serum and urine. The method is linear over at least two decades and detection limits are around 40 microg/l. A single capillary, flushed only once a week with a sodium hydroxide solution, was used without problems for the analysis of ca. 900 samples during 1 year. The robustness of the system was very good: no blocking of loop, interface or capillary was found during this period. Furthermore, the system was successfully used for overnight runs.
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Affiliation(s)
- J R Veraart
- Vrije Universiteit, Department of General and Analytical Chemistry, Amsterdam, The Netherlands
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29
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Abstract
Therapeutic drug monitoring is commonly used in both the ambulatory and hospital patient care settings. Routine measurement of concentrations of therapeutic agents in biological fluids is critical for certain drugs to maintain therapeutic benefit with minimizing drug-associated toxicities. Many analytical laboratory techniques are currently available to measure drug concentrations in biological samples. Recently there has been an increased interest in the use of capillary electrophoresis (CE) for measuring concentrations of therapeutic drugs in patient samples. However, while there are numerous reports of CE being used to measure drug concentrations in solution and pharmaceutical dosage forms, there are relatively few reports of the use of CE for measuring therapeutic agents in patient samples. The purpose of this paper is to provide an overview of methods currently used to measure therapeutic drugs in patient samples along with possible future trends for the use of CE in therapeutic drug monitoring.
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Affiliation(s)
- L J Brunner
- College of Pharmacy, The University of Texas at Austin, 78712-1074, USA.
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30
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Couderc F, Caussé E, Bayle C. Drug analysis by capillary electrophoresis and laser-induced fluorescence. Electrophoresis 1998; 19:2777-90. [PMID: 9870374 DOI: 10.1002/elps.1150191605] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This review briefly presents the different laser-induced fluorescence detectors, outlines the different dyes used to derivatize molecules which are used with capillary electrophoresis/laser-induced fluorescence (CE-LIF), and provides an overview and current status of CE-LIF in drug analysis.
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Affiliation(s)
- F Couderc
- Université Paul Sabatier, Laboratoire de Biologie Moléculaire Eucaryotes, Toulouse, France.
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31
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Emara S, Askal H, Masujima T. Rapid determination of methotrexate in plasma by high-performance liquid chromatography with on-line solid-phase extraction and automated precolumn derivatization. Biomed Chromatogr 1998; 12:338-42. [PMID: 9861494 DOI: 10.1002/(sici)1099-0801(199811/12)12:6<338::aid-bmc759>3.0.co;2-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A high-performance liquid chromatographic system, combining solid-phase extraction and automated precolumn derivatization is described for the routine determination of methotrexate in human plasma. The sample extraction and elution onto the analytical column were performed automatically and concomitantly using the column-switching technique and a protein-coated precolumn. Cerium (IV) trihydroxyhydroperoxide (CTH) was introduced as a packed oxidant before the analytical column for the conversion of methotrexate into highly fluorescent products. The oxidative-cleavage of methotrexate occurs during the flow of 0.04 M phosphate buffer (pH 3.5) containing plasma sample through CTH column with a flow rate of 0.5 mL/min at 40 degrees C. The fluorescent products were transferred to the protein-coated precolumn, which was then flushed with the same buffer for clean-up and enrichment from plasma sample. The trapped substances were desorbed from the precolumn and eluted onto the ODS/TM analytical column by isocratical elution with a mobile phase containing 0.05 M phosphate buffer, pH 6.6 and acetonitrile (90-10, v/v) for subsequent separation. The fluorescent products were detected fluorimetrically at excitation and emission wavelengths of 367 and 463 nm, respectively. The complete analysis was achieved within 15 min per sample. The calibration graph was linear in the range of 50-500 ng/mL of methotrexate and there was no interference from endogenous components.
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Affiliation(s)
- S Emara
- Faculty of Pharmacy, Department of Analytical Chemistry, Suez Canal University, Ismailia, Egypt
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32
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Abstract
Because of the ease of analysis and the high resolution, drug analysis is becoming the best example for the application of capillary electrophoresis. Therapeutic drug monitoring is a specialized area of drug analysis performed in clinical laboratories for patient care. CE offers high resolution and speed with the low operating costs needed in patient care. However, CE has a few limitations, mainly poor detection limits and precision. Simple methods of stacking, which enhance drug detection to overcome the poor sensitivity of CE are stressed. Serum has a unique matrix with a high content of proteins and salts which can have adverse effects on separation by CE. For successful analysis, special maneuvers are employed to decrease these matrix effects. Studies that have addressed the improvement of the precision of CE are summarized. CE offers the possibility of bringing chiral separations into the routine arena.
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Affiliation(s)
- Z K Shihabi
- Pathology Department, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157, USA
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33
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Chiang SC, Li SF. Separation of porphyrins by capillary electrophoresis in fused-silica and ethylene vinyl acetate copolymer capillaries with visible absorbance detection. Biomed Chromatogr 1997; 11:366-70. [PMID: 9413617 DOI: 10.1002/(sici)1099-0801(199711)11:6<366::aid-bmc708>3.0.co;2-g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A mixture of 5 porphyrins were separated by capillary electrophoresis. A UV-VIS detector was used to detect the separated components. Separation was performed in 2 types of capillaries, i.e. fused-silica and ethylene vinyl acetate copolymer (EVA) plastic capillaries. The concentration limit of detection (CLOD), mass limit of detection (MLOD), and relative standard deviations (RSD) of migration time and area were investigated. LOD was comparable to that of epi-fluorescence detection. LOD was lower when separation was performed in EVA capillary compared to fused-silica capillary. RSD of migration times of the porphyrins when separated in fused-silica capillary ranges between 0.5 to 1.6% and in EVA capillary ranges between 0.3 to 1.2%. Area RSD in fused-silica capillary ranges between 7 to 20% and in EVA capillary ranges between 4.7 to 12.3%. Urine spiked with porphyrins was also analysed by CE using fused-silica and EVA capillaries. Analysis of urine sample spiked with porphyrins showed that stacking effect of porphyrins was observable only in fused-silica and not in EVA capillary. This led to similar LOD in fused-silica capillary to those for EVA capillary.
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Affiliation(s)
- S C Chiang
- CE Resources Pte Ltd., Innovation Centre, Singapore, Republic of Singapore
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34
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Levêque D, Gailion-Renault C, Monteil H, Jehl F. Capillary electrophoresis for pharmacokinetic studies. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 697:67-75. [PMID: 9342657 DOI: 10.1016/s0378-4347(97)00335-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Different analytical techniques involving capillary electrophoresis for the determination of drugs and metabolites in biological fluids are described. Pharmacokinetic studies carried out using capillary electrophoresis are presented, as well as the in vitro metabolism investigations. The advantages and the limitations of capillary electrophoresis for pharmacokinetic studies are discussed.
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Affiliation(s)
- D Levêque
- Laboratory of Pharmacokinetics, Institute of Bacteriology, Strasbourg, France
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35
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Lehmann R, Voelter W, Liebich HM. Capillary electrophoresis in clinical chemistry. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 697:3-35. [PMID: 9342655 DOI: 10.1016/s0378-4347(97)00183-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Since its introduction, capillary electrophoresis has diversified, spreading out into different specialized fields covering solutions for almost any analytical questions arising in research laboratories. In the context of clinical chemistry, results must be provided at low costs and in a clinically relevant time frame; however, the attributes which have made capillary electrophoresis such a successful tool in basic research are identical to those attracting clinical laboratories: speed (more efficient, less labor-intensive), low costs (minimal buffer consumption), small sample volume (reduced blood collection volume from patient), increased selectivity (determination of multiple solutes in one run), and versatility (detection of analytes over the wide range of molecular masses and chemical composition). Nevertheless, it should be mentioned that there are still some drawbacks at this stage to be solved in the near future, such as lack of sensitivity for many clinical applications or the constraint to measure in a sequential mode. The aim of this survey is to familiarize clinical chemists, as well as chemists, with a short introduction to capillary electrophoresis, followed by chapters reviewing prominent fields of applications and the latest developments in clinical chemistry.
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Affiliation(s)
- R Lehmann
- Abteilung Innere Medizin IV, Stoffwechselkrankheiten und Klinische Chemie, Medizinische Klinik und Poliklinik der Universität, Tübingen, Germany
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36
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Guzman NA, Park SS, Schaufelberger D, Hernandez L, Paez X, Rada P, Tomlinson AJ, Naylor S. New approaches in clinical chemistry: on-line analyte concentration and microreaction capillary electrophoresis for the determination of drugs, metabolic intermediates, and biopolymers in biological fluids. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 697:37-66. [PMID: 9342656 DOI: 10.1016/s0378-4347(97)00275-2] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The use of capillary electrophoresis (CE) for clinically relevant assays is attractive since it often presents many advantages over contemporary methods. The small-diameter tubing that holds the separation medium has led to the development of multicapillary instruments, and simultaneous sample analysis. Furthermore, CE is compatible with a wide range of detectors, including UV-Vis, fluorescence, laser-induced fluorescence, electrochemistry, mass spectrometry, radiometric, and more recently nuclear magnetic resonance, and laser-induced circular dichroism systems. Selection of an appropriate detector can yield highly specific analyte detection with good mass sensitivity. Another attractive feature of CE is the low consumption of sample and reagents. However, it is paradoxical that this advantage also leads to severe limitation, namely poor concentration sensitivity. Often high analyte concentrations are required in order to have injection of sufficient material for detection. In this regard, a series of devices that are broadly termed 'analyte concentrators' have been developed for analyte preconcentration on-line with the CE capillary. These devices have been used primarily for non-specific analyte preconcentration using packing material of the C18 type. Alternatively, the use of very specific antibody-containing cartridges and enzyme-immobilized microreactors have been demonstrated. In the current report, we review the likely impact of the technology of capillary electrophoresis and the role of the CE analyte concentrator-microreactor on the analysis of biomolecules, present on complex matrices, in a clinical laboratory. Specific examples of the direct analysis of physiologically-derived fluids and microdialysates are presented, and a personal view of the future of CE in the clinical environment is given.
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Affiliation(s)
- N A Guzman
- R. W. Johnson Pharmaceutical Research Institute, Raritan, NJ 08869, USA
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37
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Enlund AM, Westerlund D. Enhancing detectability in CE by combining an isotachophoretic preconcentration with capillary zone electrophoresis in a single capillary. Chromatographia 1997. [DOI: 10.1007/bf02496325] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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38
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Roche ME, Oda RP, Lawson GM, Landers JP. Capillary electrophoretic detection of metabolites in the urine of patients receiving hypoglycemic drug therapy. Electrophoresis 1997; 18:1865-74. [PMID: 9372282 DOI: 10.1002/elps.1150181024] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Micellar electrokinetic chromatography (MEKC) in tandem with diode array detection (DAD) has been exploited as an analytical method for the separation and detection of sulfonylurea drugs. The ultimate goal is the development of an assay to detect these drugs or their metabolites in urine as a means of diagnosing sulfonylurea drug abuse. Using a separation buffer consisting of 5 mM borate/5 mM phosphate/75 mM sodium cholate, separation of both the second and third generation sulfonylurea drugs can be achieved. The characteristic absorbance spectra associated with each of the third generation drugs, glipizide and glyburide, allow for their identification in mixtures. Coinjection of glyburide, its primary metabolite, hydroxy glyburide, and glipizide demonstrated that the metabolite was resolved from the parent drug but shared its absorbance spectral properties. MEKC analysis of a series of solid phase-extracted urine samples from patients prescribed glipizide or glyburide, as well as from control patients not ingesting the drug, showed that the parent compounds were difficult to detect in the urine. However, the use of DAD allowed for detection of metabolites in the urine of these patients. With glyburide patients, only primary metabolites were detected, while urine from patients on glipizide showed a series of peaks whose absorbance spectra was consistent with the presence of both primary and secondary metabolites. In addition, the intensity of the metabolite peaks corresponded reasonably well with the respective dose and in vivo time interval associated with the urine collection. This study shows that MEKC with DAD has potential for further exploration as a clinical assay for detecting surreptitious abuse of sulfonylurea drugs.
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Affiliation(s)
- M E Roche
- Department of Biochemistry and Molecular Biology, Mayo Clinic/Foundation, Rochester, MN, USA
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39
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Song JM, Inoue T, Kawazumi H, Ogawa T. Highly sensitive detection using laser two-photon excited fluorescence in capillary electrophoresis. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(96)00937-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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40
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Yu Z, Westerlund D, Boos KS. Determination of methotrexate and its metabolite 7-hydroxymethotrexate by direct injection of human plasma into a column-switching liquid chromatographic system using post-column photochemical reaction with fluorimetric detection. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 689:379-86. [PMID: 9080325 DOI: 10.1016/s0378-4347(96)00357-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A simple, sensitive and fully automated column-switching system by direct injection of plasma samples for determination of methotrexate and its metabolite 7-hydroxymethotrexate was developed. The system utilized a C8 alkyl-diol silica precolumn coupled with a LiChrospher RP-18 analytical column, followed by a photoreactor and fluorimetric detection. The photo-oxidative irradiation was accomplished at UV 254 nm in the presence of 0.1% hydrogen peroxide in the eluent. Studies showed that the fluorimetric response was influenced by the reaction time, the degree of the reactor's transparency and the choice of the working wavelengths. By optimizing the content of acetonitrile in the eluent, methotrexate can be separated from 7-hydroxymethotrexate completely. The method validation revealed quantitative recoveries (> or = 94%) with coefficients of variation < or = 4.4%. The limits of detection and quantitation for determination of methotrexate were 0.20 and 0.36 ng, respectively, corresponding to 2.0 and 3.6 ng/ml for an injection volume of 100 microliters. It was possible to enhance the sensitivity further by injecting larger plasma volumes, up to 500 microliters.
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Affiliation(s)
- Z Yu
- Uppsala University Biomedical Centre, Sweden
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41
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Emara S, Razee S, Khedr A, Masujima T. On-line precolumn derivatization for HPLC determination of methotrexate using a column packed oxidant. Biomed Chromatogr 1997; 11:42-6. [PMID: 9051216 DOI: 10.1002/(sici)1099-0801(199701)11:1<42::aid-bmc621>3.0.co;2-f] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A high-performance liquid chromatographic method involving on-line precolumn oxidative cleavage and fluorimetric detection was developed for the determination of methotrexate in plasma. Plasma samples were subjected to protein precipitation followed by solvent purification and then injection into the chromatographic system. Cerium (IV) trihydroxyhydroperoxide (CTH) was introduced as a packed oxidant before analytical column for the conversion of methotrexate into highly fluorescent 2,4-diaminopteridine derivatives. The oxidative cleavage of methotrexate occurs during the flow of 0.04 M phosphate buffer (pH 3.5) containing the drug through CTH column with a flow-rate of 0.2 mL/min at 40 degrees C. The separation was performed on a reversed-phase column (ODS/TM) using a mobile phase consisting of phosphate buffer (0.05 M, pH 6.6) and acetonitrile (90:10 v/v). The fluorescent products were monitored fluorimetrically at emission and excitation wavelengths of 463 and 367 nm, respectively. Validation of accuracy and precision were satisfactory for both within- and between-run assays. All coefficients of variance were less than 4% and mean relative errors were within 1.11% to 7.83%. The average recovery was found to be 93.74% to 98.11%. The proposed method is highly sensitive, specific and applicable to biological fluids.
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Affiliation(s)
- S Emara
- Faculty of Pharmacy, Assiut University, Egypt
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42
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Naylor S, Benson LM, Tomlinson AJ. Application of capillary electrophoresis and related techniques to drug metabolism studies. J Chromatogr A 1996; 735:415-38. [PMID: 8767751 DOI: 10.1016/0021-9673(96)00068-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The use of capillary electrophoresis (CE) for the separation of small organic molecules such as pharmaceutical agents and drug/xenobiotic metabolites has become increasingly popular. This has arisen, at least in part, from the complimentary mode of separation afforded by CE when compared to the more mature technique of HPLC. Other qualities of CE include relative ease of method of development, rapid analysis, and low solvent consumption. The recent introduction of a variety of detector systems (including UV diode array, laser-induced fluorescence, conductivity) and the demonstrated coupling of CE to MS have also aided acceptance of this technology. In the present report, we review the role of CE coupled to various detector systems including a mass spectrometer for the characterization of both in vitro and in vivo derived drug metabolite mixtures. Attributes of CE for this application are demonstrated by discussion of metabolism studies of the neuroleptic agent haloperidol. Various aspects of the development and use of CE and CE-MS for the characterization of haloperidol metabolites, including criteria for selection of parameters such as pH, ionic strength, extent of organic modification, and the use of nonaqueous capillary zone electrophoresis are discussed. We also consider potential limitations of CE and CE-MS for drug metabolism research and describe the introduction of membrane preconcentration-CE (mPC-CE) and mPC-CE-MS as a solution that overcomes the rather poor concentration limits of detection of CE methods without compromising the resolution of analytes or separation efficiency of this technique.
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Affiliation(s)
- S Naylor
- Mayo Clinic, Rochester, MN 55905, USA
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43
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Caslavska J, Gassmann E, Thormann W. Modification of a tunable UV-visible capillary electrophoresis detector for simultaneous absorbance and fluorescence detection: profiling of body fluids for drugs and endogenous compounds. J Chromatogr A 1995; 709:147-56. [PMID: 7581843 DOI: 10.1016/0021-9673(95)00115-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Using fused-silica optical fibres for fluorescence light collection and bandpass filters for selection of emission wavelengths, a capillary electrophoresis detection cell of a conventional, tunable UV-Vis absorbance detector was adapted for simultaneous fluorescence (at selected emission wavelength) and absorbance (at selected excitation wavelength) detection. Detector performance is demonstrated with the monitoring of underivatized fluorescent compounds in body fluids by micellar electrokinetic capillary chromatography with direct sample injection. Compared with UV absorption detection, fluorescence detection is shown to provide increased selectivity and for selected compounds also up to tenfold higher sensitivity. Examples studied include screening for urinary indole derivatives (tryptophan, 5-hydroxytryptophan, tyrosine, 3-indoxyl sulfate and 5-hydroxyindole-3-acetic acid) and catecholamine metabolites (homovanillic acid and vanillylmandelic acid) and the monitoring of naproxen in serum, quinidine in serum and urine and of salicylate and its metabolites in serum and urine.
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Affiliation(s)
- J Caslavska
- Department of Clinical Pharmacology, University of Berne, Switzerland
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44
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Pálmarsdóttir S, Edholm LE. Enhancement of selectivity and concentration sensitivity in capillary zone electrophoresis by on-line coupling with column liquid chromatography and utilizing a double stacking procedure allowing for microliter injections. J Chromatogr A 1995. [DOI: 10.1016/0021-9673(94)01047-i] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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45
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Lu G, Jun HW. Determination of Trace Methotrexate and 7-OH-Methotrexate in Plasma by High-Performance Liquid Chromatog-Raphy with Fluorimetric Detection. ACTA ACUST UNITED AC 1995. [DOI: 10.1080/10826079508009228] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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46
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Studies on the retention behaviour of a group of organic anions of biochemical interest on quaternary bonded silica columns equilibrated with a functionally coherent series of counterions. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)00621-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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47
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Flurer CL, Wolnik KA. Chemical profiling of pharmaceuticals by capillary electrophoresis in the determination of drug origin. J Chromatogr A 1994; 674:153-63. [PMID: 8075768 DOI: 10.1016/0021-9673(94)85223-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Capillary electrophoresis has been utilized to detect trace components in bulk pharmaceutical products, with emphasis on the identification of differences among manufacturers that can be used for source verification in suspect/counterfeit cases. Micellar electrokinetic capillary chromatography with sodium dodecyl sulfate was used in the analyses of beta-lactam antibiotics. The aminoglycoside clindamycin phosphate and the macrolide erythromycin stearate were analyzed using borate buffers with direct UV detection. Methyl-beta-cyclodextrin was used as a buffer additive in the erythromycin studies. Determination of product potency using peak area ratios has been demonstrated for ampicillin and clindamycin phosphate.
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Affiliation(s)
- C L Flurer
- National Forensic Chemistry Center, US Food and Drug Administration, Cincinnati, OH 45202
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48
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Reid R. Electrophoretic behaviour of a group of organic anions of biochemical interest in a functionally coherent series of buffers. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)80346-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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49
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Dethy JM, De Broux S, Lesne M, Longstreth J, Gilbert P. Stereoselective determination of verapamil and norverapamil by capillary electrophoresis. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1994; 654:121-7. [PMID: 8004233 DOI: 10.1016/0378-4347(93)e0455-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
An analytical method has been developed to determine simultaneously the verapamil and norverapamil enantiomers in human plasma using capillary electrophoresis. Among the cyclodextrins tested as chiral selector, only trimethyl-beta-cyclodextrin was suitable to resolve the four enantiomers. The analysis was achieved in less than 10 min. Selectivity, linearity, precision and accuracy were evaluated before the chiral method was successfully implemented for routine use to simultaneously determine the four enantiomers in several thousands of human plasma samples. The robustness of the capillary electrophoretic method and its suitability were demonstrated by the coefficients of variation which were lower than 11%, even at the limit of quantification (2.5 ng/ml), for the analysis of more than one hundred quality control samples.
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Affiliation(s)
- J M Dethy
- SEARLE European Development Centre, Mont-Saint-Guibert, Belgium
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50
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Gonzalez E, Laserna JJ. Capillary zone electrophoresis for the rapid screening of banned drugs in sport. Electrophoresis 1994; 15:240-3. [PMID: 7913016 DOI: 10.1002/elps.1150150141] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Capillary zone electrophoresis was used to analyze some drugs illegally used in sports. The spectroscopic characteristics and electrophoresis migration parameters of diuretics, narcotics-analgesics and beta-blockers were established. Analytical figures of merit including parameters on the precision of migration and limits of detection are discussed. Results for the separation of drugs of different doping families are discussed. An analysis of urine from a patient receiving daily doses of atenolol is presented.
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Affiliation(s)
- E Gonzalez
- Department of Analytical Chemistry, Faculty of Sciences, University of Malaga, Spain
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