Capillary electrophoresis speciation

G. Forte, M. D Amato and S. Caroli, Capillary electrophoresis speciation analysis of various arsenical compounds, Microchem. J., 79,15-19, 2005. 

Russell and Rabenstein [43] described a speciation and quantitation method for underivatized and derivatized penicillamine, and its disulfide, by capillary electrophoresis. Penicillamine and penicillamine disulfide were determined by capillary electrophoresis on a capillary (24 cm x 25 pm i.d. or 50 cm x 50 pm i.d. for underivatized thiols) with detection at 357 nm (200 nm for underivatized thiols). The run buffer solution was 0.1 M phosphate (pH 2.3). Detection limits were 20-90 pM without derivatization, and 5-50 pM after derivatization. Calibration graphs were linear from 1 pM to 5 mM thiols. 

I. Ah, H.Y. Aboul-Enein, Instrumental methods in metal ions speciation Chromatography, capillary electrophoresis and electrochemistry, New York Taylor Francis (2006). 

Dabek-Zlotorzynska, E., Lai, E.P.C. and Timerbaev, A.R. (1998) Capillary electrophoresis the state-of-the-art in metal speciation studies. Anal. Chim. Acta, 359, 1-26. 

Liu, Y., Lopez-Avila, V, Zhu, J.J., Wiederin, D.R. and Beckert, W.F. (1995) Capillary electrophoresis coupled on-line with inductively coupled plasma-mass spectrometry for elemental speciation. Anal Chem., 67, 2020-2025. 

Magnuson, M.L., Creed, J.T. and Brockhoffl C.A. (1997) Speciation of arsenic compounds in drinking water by capillary electrophoresis with hydrodynamically modified electro-osmotic flow detected through hydride generation inductively coupled plasma mass spectrometry with a membrane gas-liquid separator./. Anal. At. Spectrom., 12, 689-695. 

Michalke, B. and Schramel, R (1997) Coupling capillary electrophoresis with ICP-MS for speciation investigations. Fresenius J. Anal. Chem., 357, 594-599. 

Olesik, J.W., Kinzer, J.A. and Olesik, S.V (1995) Capillary electrophoresis inductively-coupled plasma spectrometry for rapid elemental speciation. Anal. Chem., 67, 1-12. 

There are few methods which can measure well-defined metal fractions with sufficient sensitivity for direct use with environmental samples (approach B in Fig. 8.2). Nevertheless, this approach is necessary in the experimental determination of the distribution of compounds that are labile with respect to the time scales of the analytical method. Recent literature indicates that high-performance liquid (HPLC) and gas chromatographic (GC) based techniques may have such capabilities (Batley and Low, 1989 Chau and Wong, 1989 van Loon and Barefoot, 1992 Kitazume et al, 1993 Rottmann and Heumann, 1994 Baxter and Freeh, 1995 Szpunar-Lobinska et al, 1995 Ellis and Roberts, 1997 Vogl and Heumann, 1998). The ability to vary both the stationary and mobile phases, in conjunction with suitable detector selection (e.g. ICP-MS), provides considerable discriminatory power. HPLC is the superior method GC has the disadvantage that species normally need to be derivatised to volatile forms prior to analysis. Capillary electrophoresis also shows promise as a metal speciation tool its main advantage is the absence of potential equilibria perturbation, interactions... 

Capillary electrophoresis (CE) provides high resolution for separation of chemical compounds. Separations of metal ions, of metal ions in different oxidation states and of organometallic compounds are all possible with appropriate CE conditions. This technique is being investigated for speciation. Since sample volumes in CE are generally very small, a detector capable of very low detection limits is desirable. Thus, ICP-MS has been combined with CE to provide a means for studying metal speciation. CE-ICP-MS procedures have been described for the separations of platinum species (Michalke and Schramel, 1996), selenium species (Kumar et al., 1995 Michalke and Schramel, 1996) and arsenic species (Magnuson et al., 1997). Detection limits were about 1 mgl 1 (platinum species) and 10 and 24 pg for Sclv and Scvl, respectively. An application of CE-ICP-MS to platinum species in soils is described in Section 15.8.6. 

Lustig, S., Michalke, B., Beck, W. and Schramel, R (1998) Platinum speciation with hyphenated techniques high performance liquid chromatography and capillary electrophoresis on-line coupled to an inductively coupled plasma mass spectrometer -application to aqueous extracts from a platinum treated soil. Fresenius J. Anal. Chem., 360,18-23. 

Michalke, B. and Schramel, P. (1996) Hyphenation of capillary electrophoresis to inductively coupled mass spectrometry as an element-specific detection method for metal speciation. J. Chromatogr. A, 750, 51-62. 

Yang, W.P., ZJ. Zhang, and W. Deng. 2003. Speciation of chromium by in-capillary reaction and capillary electrophoresis with chemiluminescence detection. J. Chromatogr. A 1014 203-214. 

Li, Y., X.-B. Yin, and X.-P. Yan. 2008. Recent advances in on-line coupling of capillary electrophoresis to atomic absorption and fluorescence spectrometry for speciation analysis and studies of metal-biomolecule interactions. Anal. Chim. Acta 615 105-114. 

Michalke, B. and P. Schramel. 1998. Selenium speciation by interfacing capillary electrophoresis with inductively coupled plasma-mass spectrometry. Electrophoresis 19 270-275. 

Michalke, B., O. Schramel, and A. Kettrup. 1999. Capillary electrophoresis coupled to inductively coupled plasma mass spectrometry (CE/ICP-MS) and to electrospray ionization mass spectrometry (CE/ ESI-MS) An approach for maximum species information in speciation of selenium. Fresenius J. Anal. Chem. 363 456—459. 

Another key factor in the popularity of the technique is its increasingly widespread use in speciation chemistry. The current awareness of the importance of the chemical form in which an element is present in food (e.g., the oxidation state, the nature of the ligands, and the molecular structure), on its possible absorption and fate inside the body, has made elemental speciation a prominent topic of present research in the food science. If speciation critically influences the bioavailability, essentiality, or toxicity of an element, the analytical techniques that enable species discrimination and quantification gather prominence. ICP-MS has the capability for quantifying metal (metalloid)-containing species in a chromatographic or capillary electrophoresis effluent or, as recently demonstrated, in a gel spot after SDS-PAGE via electrothermal vaporization (ETV) or laser ablation (LA) [4, 5]. Hence, it has firmly established as a sensitive,... 

M. Van Holderbeke, Y. Zhao, F. Vanhaecke, L. Moens, R. Dams, P. Sandra, Speciation of six arsenic compounds using capillary electrophoresis-inductively coupled plasma mass spectrometry, J. Anal. Atom. Spectrom., 14 (1999), 229-234. 

S. S. Kannamkumarath, Katarzyna Wrobel, Kazimierz Wrobel, C. B Hymer, J. A. Caruso, Capillary electrophoresis D inductively coupled plasmaDmass spectrometry an attractive complementary technique for elemental speciation analysis, J. Chromatogr. A, 975 (2002), 245 D 266. 

J. A. Day, S. S. Kannamkumarath, E. G. Yanes, M. M. Bayon, J. A. Caruso, Chiral speciation of Marfey s derivatized DL-selenomethionine using capillary electrophoresis with UV and ICP-MS detection, J. Anal. Atom. Spectrom., 17 (2002), 27D31. 

In past years, on line chromatographic coupling techniques such as HPLC and CE coupled to ICP-MS with the isotope dilution technique have been used for element quantification in speciation analysis. An interesting application of the isotope dilution technique in medical research was proposed recently by Prange and co-workers, who added highly enriched " S, Cu, Zn and Cd spikes to the interface of the CE-ICP-MS system. The authors separated isoforms of metallothionein (e.g., of rabbit liver) by capillary electrophoresis and quantified S, Cd, Cu and Zn concentrations in isoforms by ICP-SFMS using the isotope dilution technique. A new selenized yeast reference material (SELM-1) for methionine, selenomethionine (SeMet) and total selenium content has also certified by an intercomparison exercise. ... 

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