Non-aqueous capillary electrophoresis

WRIGHT L P, AUCAMP J P and APOSTOLIDES z (2001) Analysis ofblackteatheaflavinsby non-aqueous capillary electrophoresis , J Chromatog A, 919, 205-13. 

Fig. 3.172. Non-aqueous capillary electrophoresis with electrochemical detection of a dye mixture containing (a) 1.7 jUg/ml malachite green, (b) 0.70 jug/ml crystal violet, (c) 4.3 /ig/ml rhodamine B, and (d) 9.1 X 10-6 M ferrocene. Experimental conditions capillary dimensions, 95 cm X 75 pm i.d. running electrolyte, acetonitrile containing 1 M HAc and 10 mM NaAc electrokinetic injection, 20 s 5 kV separation voltage 20 kV applied detection potential, 1.55 V. Reprinted with permission from F.-M. Matysik [206].

F.-M. Matysik, Potentialities of electrochemical detection in conjunction with non-aqueous capillary electrophoresis. Electrochim. Acta, 43 (1998) 3475-3482. 

F.-M. Matysik, Non-aqueous capillary electrophoresis with electrochemical detection. J. Chromatogr.A, 802 (1998) 349-354. 

M. Vaher, M. Koel and M. Kaljurand, Non-aqueous capillary electrophoresis in acetonitrile using ionic-liquid buffer electrolytes. Chromatographia Supplement, 53 (2001) 302-306. 

Delmar Cantu, M., Hillebrand, S., Costa Queiroz, M. E., Lanyas, F. M., and Carrilho, E. (2004). Validation of non-aqueous capillary electrophoresis for simultaneous determination of four tricyclic antidepressants in pharmaceutical formulations and plasma samples. /. Chromatogr. B 799(1), 127-132. 

Tjornelund, J., and Hansen, S. H. (1997). Validation of a simple method for the determination of oxytetracycline in ointment by non-aqueous capillary electrophoresis. J. Pharm. Biomed. Anal. 15(8), 1077-1082. 

After a short introduction into the relevance of Impurity profiling for regulatory authorities, public health, and the pharmaceutical industry, an overview is presented based on the various modes of capillary electrophoresis that have been used in drug impurity analysis. The applications of capillary zone electrophoresis, non-aqueous capillary electrophoresis, micellar electrokinetic capillary chromatography, microemulsion electrokinetic capillary chromatography, capillary gel electrophoresis, and capillary electrochromatography are presented consecutively. 

Hernandez, M., Borrull, R, and Calull, M. (2000). Determination of oxytetracycline and some impurities in plasma by non-aqueous capillary electrophoresis using solid-phase extraction. Chromatographia 52, 279—284. 

Dedicated applications of capillary zone electrophoresis (CZE) coupled to MS are discussed, particularly in the field of drug analysis. Development of other capillary-based electrodriven separation techniques such as non-aqueous capillary electrophoresis (NACE), micellar electrokinetic chromatography (MEKC), and capillary electrochromatography (CEC) hyphenated with MS are also treated. The successful coupling of these electromigration schemes with MS detection provides an efficient and sensitive analytical tool for the separation, quantitation, and identification of numerous pharmaceutical, biological, therapeutic, and environmental compounds. 

The recent introduction of non-aqueous media extends the applicability of CE. Different selectivity, enhanced efficiency, reduced analysis time, lower Joule heating, and better solubility or stability of some compounds in organic solvent than in water are the main reasons for the success of non-aqueous capillary electrophoresis (NACE). Several solvent properties must be considered in selecting the appropriate separation medium (see Chapter 2) dielectric constant, viscosity, dissociation constant, polarity, autoprotolysis constant, electrical conductivity, volatility, and solvation ability. Commonly used solvents in NACE separations include acetonitrile (ACN) short-chain alcohols such as methanol (MeOH), ethanol (EtOH), isopropanol (i-PrOH) amides [formamide (FA), N-methylformamide (NMF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA)] and dimethylsulfoxide (DMSO). Since NACE—UV may present a lack of sensitivity due to the strong UV absorbance of some solvents at low wavelengths (e.g., formamides), the on-line coupling of NACE... 

Steiner, R, and Hassel, M. (2005). Influence of solvent properties on separation and detection performance in non-aqueous capillary electrophoresis-mass spectrometry of basic analytes.. Chromatogr. A 1068, 131 — 142. 

MT Bowser, ED Sternberg, DDY Chen. Quantitative description of migration behavior of porphyrins based on the dynamic complexation model in a non-aqueous capillary electrophoresis system. Electrophoresis 18 82—91, 1997. 

Tjornelund, J. and Hansen, S. H., Non-aqueous capillary electrophoresis of drugs Properties and application of selected solvents, /. Biochem. Biophys. Methods, 38,139-153,1999. 

Vaher, M., Koel, M., and Kaljurand, M., Application of l-alkyl-3-methy-limidazolium-based ionic liquids in non-aqueous capillary electrophoresis, /. Chromatogr. A, 979,27-32,2002. 

Bianco, G., Schmitt-Kopplin, R, De Benedetto, G., Kettrup, A., and Cataldi, T. R. (2002). Determination of glycoalkaloids and relative aglycones by non-aqueous capillary electrophoresis coupled with electrospray ionization-ion trap mass spectrometry. Electrophoresis 23,2904—2912. 

Menzinger, F., Schmitt-Kopplin, E, Frommberger, M., Freitag, D., and Kettrup, A. (2001). Partial-filling micellar electrokinetic chromatography and non-aqueous capillary electrophoresis for the analysis of selected agrochemicals. Fresenius J. Anal. Chem. 371,25-34. 

Carabias-Martinez, R., E. Rodriguez-Gonzalo, E. Miranda-Cruz, J. Dominguez-Alvarez, and J. Hernandez-Mendez. 2006. Comparison of a non-aqueous capillary electrophoresis method with high performance liquid chromatography for the determination of herbicides and metabolites in water samples. J. Chromatogr. A 1122 194—201. 

Svensson et al reported a non-aqueous capillary electrophoresis method for the analysis of pyridinyl-methyl-sulfinyl-benzimidazoles [15]. 

Riekkola M-L, Jussila M, Possas SP, Valko IE. Non-aqueous capillary electrophoresis. J Chromatogr A 2000 892 155. 

Hansen, S.H., Sheribah, Z.A. Comparison of CZE, MEKC, MEEKC and non-aqueous capillary electrophoresis for the determination of impurities in bromazepam. J. Pharm. Biomed. Anal. 39, 322-327 (2005)... 

Tjomelund, J., Hansen, S.H. Determination of impurities in tetracycline hydrochloride by non-aqueous capillary electrophoresis. J. Chromatogr. A 737, 291-300 (1996)... 

Chiu, T.-C. Huang, M.-R Huang, C.-C. Hsieh, M.-M. Chang, H.-T. Indirect fluorescence of aliphatic carboxylic acids in non-aqueous capillary electrophoresis using me-rocyanine 540. Electrophoresis 2002, 23 (2), 449-455. 

The interaction of the polymeric analyte molecules (charged or uncharged) with the polymeric sieving media (uncharged or charged) is a general and principal method for analytical separation of water-soluble polymers. Transfer of this technique to water-insoluble polymers by applying the technique of non-aqueous capillary electrophoresis (NACE) seems feasible. 

Madej et al. [76] used a non-aqueous capillary electrophoresis (NACE) method for the screening and quantification of seven phenothiazine derivatives in blood. The optimal medium for dissolving the examined blood extracts was tested. The linear dynamic ranges were between 0.25 and 4.00 xg/mL (correlation coefficients higher than 0.996), the RSD values going from 1.21 to 9.15%, according to the compound. The detection limits were 0.08 xg/mL for promazine and 0.15 pg/mL for the rest of the drugs under study. Finally, the proposed method was applied to two forensic blood samples, and concentrations of the examined phenothiazines determined by the HPLC and NACE methods were found to be comparable. 

Chen, M.J., Chen, H.S., Lin, C.Y., and Chang, H.T. 1999. Indirect detection of organic acids in non-aqueous capillary electrophoresis. Journal of Chromatography A 853 171-180. 

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