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El Deeb S, Dawwas HA, Gust R. Recent methodological and instrumental development in MEKC. Electrophoresis 2013; 34:1295-303. [PMID: 23417897 DOI: 10.1002/elps.201200574] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 01/04/2013] [Accepted: 01/05/2013] [Indexed: 11/08/2022]
Abstract
The review gives an update about the methodological and instrumental developments in micellar electrokinetic capillary chromatography as a type of CE analytical technique. Here, the last two years development of the technique are particularly presented. Recent approaches to improve sensitivity are discussed. Newly introduced concentration techniques and experimental methods for verification of the different mechanisms and processes of micellar electrokinetic chromatography analysis are highlighted. A theoretical model to explain changes in separation and electrophoretic mobility order of fully charged analytes are demonstrated. Modern approaches for improving compatibility of micellar electrokinetic capillary chromatography to mass spectrometry are also reported.
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Affiliation(s)
- Sami El Deeb
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
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2
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Singh S, Handa T, Narayanam M, Sahu A, Junwal M, Shah RP. A critical review on the use of modern sophisticated hyphenated tools in the characterization of impurities and degradation products. J Pharm Biomed Anal 2012; 69:148-73. [DOI: 10.1016/j.jpba.2012.03.044] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 03/21/2012] [Accepted: 03/22/2012] [Indexed: 11/30/2022]
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3
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El Deeb S, Iriban MA, Gust R. MEKC as a powerful growing analytical technique. Electrophoresis 2010; 32:166-83. [PMID: 21171121 DOI: 10.1002/elps.201000398] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 09/30/2010] [Accepted: 09/30/2010] [Indexed: 11/11/2022]
Abstract
This review summarizes the principle and the developments in MEKC in terms of separation power, sensitivity, and detection approaches more than 25 years after its appearance. Newly used surfactants are mentioned. Classical and new sample concentration techniques in MEKC are described. The different detection approaches in MEKC with advantages, limitations, and future prospects are also discussed. This review highlights the wider application of MEKC in different analytical fields. Various recent selected applications of this technique in different analytical fields are reported.
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Affiliation(s)
- Sami El Deeb
- Institute of Pharmacy, Freie Universität Berlin, Berlin, Germany
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4
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Somsen GW, Mol R, de Jong GJ. On-line coupling of electrokinetic chromatography and mass spectrometry. J Chromatogr A 2010; 1217:3978-91. [DOI: 10.1016/j.chroma.2010.01.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 12/23/2009] [Accepted: 01/08/2010] [Indexed: 11/27/2022]
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5
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Ge L, Yong JWH, Tan SN, Hua L, Ong ES. Analyses of gibberellins in coconut (Cocos nucifera L.) water by partial filling-micellar electrokinetic chromatography-mass spectrometry with reversal of electroosmotic flow. Electrophoresis 2008; 29:2126-34. [DOI: 10.1002/elps.200700717] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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6
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Ge L, Tan SN, Yong JWH, Hua L, Ong ES. Separation of cytokinin isomers with a partial filling-micellar electrokinetic chromatography-mass spectrometry approach. Electrophoresis 2008; 29:2024-32. [DOI: 10.1002/elps.200700474] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Amundsen LK, Kokkonen JT, Sirén H. Comparison of partial filling MEKC analyses of steroids with use of ESI-MS and UV spectrophotometry. J Sep Sci 2008; 31:803-13. [DOI: 10.1002/jssc.200700657] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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18 Coupling CE and microchip-based devices with mass spectrometry. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s0149-6395(07)00018-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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9
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Schappler J, Guillarme D, Rudaz S, Veuthey JL. Microemulsion electrokinetic chromatography hyphenated to atmospheric pressure photoionization mass spectrometry. Electrophoresis 2008; 29:11-9. [DOI: 10.1002/elps.200700647] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12 CE in impurity profiling of drugs. CAPILLARY ELECTROPHORESIS METHODS FOR PHARMACEUTICAL ANALYSIS 2008. [DOI: 10.1016/s0149-6395(07)00012-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Spégel P, Viberg P, Carlstedt J, Petersson P, Jörntén-Karlsson M. Continuous full filling capillary electrochromatography: Nanoparticle synthesis and evaluation. J Chromatogr A 2007; 1154:379-85. [PMID: 17449050 DOI: 10.1016/j.chroma.2007.02.092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 02/13/2007] [Accepted: 02/20/2007] [Indexed: 10/23/2022]
Abstract
Reversed phase continuous full filling capillary electrochromatography with electrospray ionisation mass spectrometric detection was performed with highly sulphated poly[styrene-co-(lauryl methacrylate)-co-(divinylbenzene)] nanoparticles. The nanoparticles that contained a hydrophobic core and a hydrophilic surface were prepared in a one step synthesis using soap free emulsion polymerisation. By changing the concentration of monomers, the polymerisation temperature, and the polarity of the dispersive phase, the size of the nanoparticles could be controlled. With the optimised conditions, nanoparticles with an average size of 157 nm were obtained. These nanoparticles were dispersed in the background electrolyte and used for reversed phase continuous full filling. An orthogonal electrospray ionisation interface was used to separate the eluting nanoparticles from the eluting analytes prior to mass spectrometry detection. Compared to previous studies on reversed phase continuous full filling, the retention, the separation efficiency, and the resolution of a homologous series of dialkyl phthalates were greatly improved.
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Affiliation(s)
- Peter Spégel
- Analytical Chemistry, Centre for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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12
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Abstract
This paper reviews recent methodological and instrumental advances in MEKC. Improvements in sensitivity arising from the use of on-line sample concentration (sweeping, stacking, and combination of both protocols) and derivatization (in-capillary reactions and coupling with flow-injection systems) and improvements in resolution obtained by changing the composition of the BGE (e.g., with organic modifiers, ionic liquids, nonionic and zwitterionic surfactants, mixed micelles, and vesicles) or using coated capillaries are discussed in detail. In addition, MS and LIF spectroscopy are examined in relation to their advantages and restrictions as applied to MEKC analysis. Some thoughts on potential future directions are also expressed.
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Affiliation(s)
- Manuel Silva
- Department of Analytical Chemistry, University of Cordoba, Cordoba, Spain.
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13
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Van Biesen G, Bottaro CS. Ammonium perfluorooctanoate as a volatile surfactant for the analysis ofN-methylcarbamates by MEKC-ESI-MS. Electrophoresis 2006; 27:4456-68. [PMID: 17058301 DOI: 10.1002/elps.200600076] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ammonium perfluorooctanoate (APFOA) was investigated as an MS-friendly surfactant for the analysis of a mixture of ten N-methylcarbamates with MEKC-ESI-MS. Because of the relatively low boiling point of perfluorooctanoic acid ( approximately 190 degrees C), APFOA can be introduced into a mass spectrometer without the adverse effects of less volatile surfactants such as SDS. With a BGE consisting of 50 mM APFOA/isopropanol (IPA) 98:2 and with 30 kV applied, a very fast separation ( approximately 6 min) was possible with only one pair of analytes comigrating. Using an experimental design with four factors (voltage, nebulizer pressure, concentration of APFOA, and concentration of IPA) we were able to resolve all analytes in just over 11 min. Sheath liquid composition and flow rate, drying gas temperature and flow rate, and fragmentor voltage were then optimized for maximum signal intensity and S/N. It was found that the faster method gave better S/N because of narrower peak widths, and detection limits in SIM mode were between 0.01 (aldicarb) and 0.08 mg/L (methomyl). Calibration curves were prepared with standards of 0.50, 1.00, and 2.00 mg/L for the analysis of samples obtained after SPE of tap water spiked with the ten N-methylcarbamates at a level of 10 microg/L. All analytes showed very good recoveries (>86%), except for the most polar analyte aldicarb sulfone (recovery of 73%), testifying for the potential use of APFOA for this kind of analyses.
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Klampfl CW. Recent advances in the application of capillary electrophoresis with mass spectrometric detection. Electrophoresis 2006; 27:3-34. [PMID: 16315165 DOI: 10.1002/elps.200500523] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This review gives an overview of applications of CE coupled to MS detection published in the literature of the last three years. The works discussed in this paper comprise a wide range of different fields of application. These include important sections such as the analysis of biomolecules, the analysis of pharmaceuticals and their metabolites in different matrices, environmental analysis, and also investigations on the composition of technical products.
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Affiliation(s)
- Christian W Klampfl
- Institute of Analytical Chemistry, Johannes Kepler University Linz, Linz, Austria.
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Mol R, de Jong GJ, Somsen GW. Atmospheric Pressure Photoionization for Enhanced Compatibility in On-Line Micellar Electrokinetic Chromatography−Mass Spectrometry. Anal Chem 2005; 77:5277-82. [PMID: 16097769 DOI: 10.1021/ac0502697] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atmospheric pressure photoionization (APPI) is presented as a novel means for the combination of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS). The on-line coupling is achieved using an adapted sheath flow interface installed on an orthogonal APPI source. Acetone or toluene is added as dopant to the sheath liquid to enhance analyte photoionization. It is demonstrated that with APPI signal suppression and interferences by the surfactant sodium dodecyl sulfate (SDS) and nonvolatile buffers can be circumvented. This implies that MEKC conditions can be selected independently from MS detection. Moreover, it is shown that both polar and apolar compounds can be photoionized, thereby also facilitating the analysis of compounds that are not amenable to electrospray ionization. Consequently, the MEKC-APPI-MS system can provide effective separation and detection of compounds of diverse character in one run using background electrolytes containing up to 50 mM SDS. Concentration limits of detection derived from extracted-ion traces (full scan mode) of test compounds were approximately 1 microg/mL, and the detection sensitivity remained unaffected during 1 day of continuous use. Overall, the system features are very favorable for applications such as drug impurity profiling as is illustrated by the analysis of mebeverine and related compounds (both charged and neutral) at the 0.25% (w/w) level.
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Affiliation(s)
- Roelof Mol
- Department of Biomedical Analysis, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
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Shamsi SA, Miller BE. Capillary electrophoresis-mass spectrometry: recent advances to the analysis of small achiral and chiral solutes. Electrophoresis 2005; 25:3927-61. [PMID: 15597424 DOI: 10.1002/elps.200406131] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We describe here the state-of-the-art development of on-line capillary electrophoresis-mass spectrometry (CE-MS) over the last two years. Technological developments included are novel designs of new interfaces and ionization sources, new capillary coatings, buffers, and micelles as well as application of various modes of CE-MS published in the recent literature. The areas of CE-MS application in analysis of small achiral and chiral solutes are covered in sections that highlight the recent advances and possibilities of each mode of CE-MS. Application areas reviewed in this paper include achiral and chiral pharmaceuticals, agrochemicals, carbohydrates, and small peptides. The separation of enantiomers using micellar electrokinetic chromatography (MEKC)-MS with molecular micelles and capillary electrochromatography (CEC)-MS using pack tapered columns appears to provide good tolerance to electrospray stability for routine on-line CE-MS. These two modes seem to be very suitable for sensitive detection of chiral pharmaceuticals in biological samples, but their use will probably increase in the near future. Overall, it seems that one mode of CE-MS, in particular capillary zone electrophoresis (CZE)-MS, is now recognized as established technique for analysis of small charged solutes, but other modes, such as MEKC-MS and CEC-MS, are still within a period of development in terms of both MS-compatible pseudostationary phases and columns as well as applications.
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Affiliation(s)
- Shahab A Shamsi
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, USA.
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Huck CW, Stecher G, Scherz H, Bonn G. Analysis of drugs, natural and bioactive compounds containing phenolic groups by capillary electrophoresis coupled to mass spectrometry. Electrophoresis 2005; 26:1319-33. [PMID: 15776479 DOI: 10.1002/elps.200410315] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review summarizes the use of capillary electrophoresis (CE) coupled to mass spectrometry (MS) for the analysis of phenolic compounds and its latest developments. Special attention is paid to the different interfaces. The instrumental setups are discussed and demonstrated in a high number of real applications.
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Affiliation(s)
- Christian W Huck
- Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innsbruck, Austria.
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Krivánková L, Brezková M, Gebauer P, Bocek P. Importance of the counterion in optimization of a borate electrolyte system for analyses of anions in samples with complex matrices performed by capillary zone electrophoresis. Electrophoresis 2004; 25:3406-15. [PMID: 15490446 DOI: 10.1002/elps.200406097] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Borate buffers are common background electrolytes for analyses of anions in capillary zone electrophoresis. Usually, sodium borate at a given pH is used and this specification seems to be sufficient for a successful analysis. In this paper, we show that free migration of OH(-) may deteriorate the analysis of a typical anionic analysis of clinical samples due to uncontrolled migration of OH(-) throughout the systems of analyzed zones and may damage the stacking of anionic analytes of interest. We have proven that the use of ammonium borate may remedy the situation where the presence of ammonium may selectively stop the free migration of OH(-) ions, slow down their effective mobility and bring their safe behavior resulting in reproducible stacking of clinically important anions. Results of real analyses of human serum samples confirmed the proposed method and proved that substitution of sodium for ammonium in borate buffers offers reliable analyses of clinical samples having chloride as the bulk component. The experimental results given in this paper are supported also by computer simulation, which can not only support the positive results but also show the dynamics of the separation that is otherwise hidden to any detection possibilities.
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Affiliation(s)
- Ludmila Krivánková
- Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
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Affiliation(s)
- Joseph A Loo
- Departments of Biochemistry and Biological Chemistry, Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
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Somsen GW, Mol R, de Jong GJ. On-line micellar electrokinetic chromatography-mass spectrometry: feasibility of direct introduction of non-volatile buffer and surfactant into the electrospray interface. J Chromatogr A 2003; 1000:953-61. [PMID: 12877207 DOI: 10.1016/s0021-9673(03)00179-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An on-line method for the coupling of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS) is presented which allows conventional MEKC conditions to be employed without further modification. The MEKC system is coupled directly to electrospray ionization (ESI) MS using a triaxial interface. A systematic study of the influence of the surfactant concentration, the nature and concentration of buffer salts and presence of organic modifier on the interface performance indicated the feasibility of the MEKC-MS approach. Effective interfacing of MEKC was achieved with both single quadrupole and ion-trap MS instruments. Using a background electrolyte containing 20 mM sodium dodecyl sulfate (SDS) and 10 mM sodium phosphate buffer, it is demonstrated that full MEKC runs of test mixtures of mebeverine and related compounds can be monitored by ESI-MS with satisfactory sensitivity. Sub-microg/ml levels of the analytes can still be detected in full scan mode, while detection limits are in the 10-50 ng/ml range when selected ion monitoring is applied. It is shown that such sensitivity would allow full-scan MS detection of 0.1% (w/w) levels of potential impurities in mebeverine. With the ion-trap instrument successful MEKC-MS/MS experiments were carried out providing information-rich MS spectra of the related compounds. Repeated MEKC-MS analyses proved that in the course of 1 day the migration time of mebeverine remained fairly constant while the MS-signal intensity only gradually decreased to approximately 65% of its original value. Once-a-day cleaning of the first part of the ion source, which takes only 5 min, suffices to preserve an optimal interface performance for a prolonged period of time.
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Affiliation(s)
- Govert W Somsen
- Department of Biomedical Analysis, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
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21
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2002; 37:765-776. [PMID: 12125010 DOI: 10.1002/jms.254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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