Separated zone detection electrophoresis

Otsuka, K., Smith, C. J., Grainger, J., Barr, J. R., Patterson, J., Tanaka, N., and Terabe, S. (1998). Stereoselective separation and detection of phenoxy acid herbicide enantiomers by cyclodextrin-modified capillary zone electrophoresis-electrospray ionization mass spectrometry. /. Chromatogr. A 817, 75-81. 

Berzas Nevado et al. [138] developed a new capillary zone electrophoresis method for the separation of omeprazole enantiomers. Methyl-/ -cyclodextrin was chosen as the chiral selector, and several parameters, such as cyclodextrin structure and concentration, buffer concentration, pH, and capillary temperature were investigated to optimize separation and run times. Analysis time, shorter than 8 min was found using a background electrolyte solution consisting of 40 mM phosphate buffer adjusted to pH 2.2, 30 mM /1-cyclodextrin and 5 mM sodium disulfide, hydrodynamic injection, and 15 kV separation voltage. Detection limits were evaluated on the basis of baseline noise and were established 0.31 mg/1 for the omeprazole enantiomers. The method was applied to pharmaceutical preparations with recoveries between 84% and 104% of the labeled contents. 

In conclusion, capillary electrophoresis in carbohydrate analysis has advantages in both separation and detection over other techniques of electrophoresis, as well as chromatography. It allows high efficiency (up to a few million plate numbers) and very good sensitivities (up to femtomolar). In addition, CE permits analysis by a variety of separation modes simply by changing the electrolyte (capillary zone electrophoresis, MEKC, CGE). 

Electrophoresis is the most powerful method available for separation and analysis of complex mixtures of charged biopolmers. This chapter provides an overview of modern electophoresis as a general introduction to the chapters which follow. The basic electrophoretic operating modes and formats for these modes are described. Means for detection of separated zones are reviewed. Finally, an approach to fully instrumental electrophoresis is discussed. 

Olvecka, E., Kaniansky, D., Poliak, B., Stanislawski, B., Separation of proteins by zone electrophoresis on-line coupled with isotachophoresis on a column-coupling chip with conductivity detection. Electrophoresis, 25,3865-3874, 2004. 

While not yet active in clinical analysis, two techniques appear to be of great interest two-dimensional (2D) maps and capillary zone electrophoresis (CZE). In 2D maps, denatured polypeptide chains are separated in two dimensions, first by surface charge (lEF) and then orthogonally by size (SDS electrophoresis). In normal human sera, for example, 600 spots are separated and detected by silver staining. 

Zone electrophoresis in capillaries is a useful approach to high-resolution separation of charged substances. Efficient heat transfer from small diameter capillaries permits the application of unusually high voltages, which promote more effective separations and increase the speed of analysis. A sample injection technique and on-line zone detection create an instrumental format for zone electrophoresis. 

The detection of individual amino polycarboxylic acids has been proposed< > based upon the separation of the mixture by zone paper electrophoresis, and by the identification of the components by comparison of the half-wave potentials of the copper chelates with those of isolated chelates. 

A method has been devised for the separation and detection of 11 antibiotics by the use of silica gel G plates for thin-layer electrophoresis. Various chromogenic reagents were used in the detection of the zones. 

In capillary zone electrophoresis (CZE), the capillary, inlet reservoir, and outlet reservoir are filled with the same electrolyte solution. This solution is variously termed background electrolyte, analysis buffer, or run buffer. In CZE, the sample is injected as a plug at the inlet end of the capillary, and sample components are resolved into separated zones according to their mass-to-charge ratio as they migrate towards the detection point. It is the simplest form of CE and the most widely used. 

Catechin and epicatechin are two flavanols of the catechin family. They are enantiomers. The capillary zone electrophoresis (CE) methods with UV-detection were developed for quantitative determination of this flavanols in green tea extracts. For this purpose following conditions were varied mnning buffers, pH and concentration of chiral additive (P-cyclodextrin was chosen as a chiral selector). Borate buffers improve selectivity of separation because borate can make complexes with ortho-dihydroxy groups on the flavanoid nucleus. 

Very recently, HPLC with fluorescence detection was recommended for improving detection sensitivities of betalains. " While this technique may be worthwhile for betaxanthin analyses, its use for betacyanins cannot be recommended. Although this technique represents a worthwhile approach requiring low amounts of solvent and sample and generally characterized by a high separation efhciency, only one study dealt with the use of capillary zone electrophoresis for betalain analyses. ... 

Wu, S. and Dovichi, N. J., Capillary zone electrophoresis separation and laser-induced fluorescence detection of zeptomole quantities of fluorescein thiohy-dantoin derivatives of amino acids, Talanta, 39, 173, 1992. 

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