Capillary zone electrophoresis techniques

Furthermore, Grossman and Soane [66] have studied the effect of molecular orientation on the electrophoretic mobility of a macro ion in free solution (the tobacco mosaic virus was a model) by using the capillary zone electrophoresis technique. 

Biomolecule Separations. Advances in chemical separation techniques such as capillary zone electrophoresis (cze) and sedimentation field flow fractionation (sfff) allow for the isolation of nanogram quantities of amino acids and proteins, as weU as the characterization of large biomolecules (63—68) (see Biopolymers, analytical techniques). The two aforementioned techniques, as weU as chromatography and centrifugation, ate all based upon the differential migration of materials. Trends in the area of separations are toward the manipulation of smaller sample volumes, more rapid purification and analysis of materials, higher resolution of complex mixtures, milder conditions, and higher recovery (69). 

Electrodriven Separation Techniques encompass a wide range of analytical procedures based on several distinct physical and chemical principles, usually acting together to perform the requh ed separation. Example of electrophoretic-based techniques includes capillary zone electrophoresis (CZE), capillary isotachophoresis (CITP), and capillary gel electrophoresis (CGE) (45-47). Some other electrodriven separation techniques are based not only on electrophoretic principles but rather on chromatographic principles as well. Examples of the latter are micellar... 

Capillary electrophoresis (CE) has several unique advantages compared to HPLC, snch as higher efficiency dne to non-parabolic fronting, shorter analytical time, prodnction of no or much smaller amounts of organic solvents, and lower cost for capillary zone electrophoresis (CZE) and fused-silica capillary techniques. However, in CZE, the most popular separation mode for CE, the analytes are separated on the basis of differences in charge and molecular sizes, and therefore neutral compounds snch as carotenoids do not migrate and all co-elute with the electro-osmotic flow. 

CE was recently used for anthocyanin analysis because of its excellent resolution. This technique has different modes capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE), micellar electrokinetic chromatography (MEKC), capillary electrochromatography (CEC), capillary isoelectric focusing (CIEE), and capillary isotachophoresis (CITP)."° CZE is the most popular method for anthocyanin... 

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. ... 

Capillary electrophoresis (CE) or capillary zone electrophoresis (CZE) is the technique most often employed in pesticide residue analysis. In its most basic form, free zone electrophoresis, a fused-silica capillary is filled with electrolyte (running buffer or background electrolyte). A potential is applied across the capillary and the cations... 

Table 1 summarizes several of the experimental methods discussed in this chapter. A need exists for new or revised methods for transport experimentation, particularly for therapeutic proteins or peptides in polymeric systems. An important criterion for the new or revised methods includes in situ sampling using micro techniques which simultaneously sample, separate, and analyze the sample. For example, capillary zone electrophoresis provides a micro technique with high separation resolution and the potential to measure the mobilities and diffusion coefficients of the diffusant in the presence of a polymer. Combining the separation and analytical components adds considerable power and versatility to the method. In addition, up-to-date separation instrumentation is computer-driven, so that methods development is optimized, data are acquired according to a predetermined program, and data analysis is facilitated. 

Amino acids derivatized with 9-fluorenylmethyl chloroformate (90) were separated by CE and determined by LIF with a pulsed laser LOD 0.5 nM (SNR 2)322. A sensitive technique for amino acids is capillary zone electrophoresis (CZE) combined with LIF of their fluorescein isothiocyanate (133) derivatives. Not all amino acids give good resolution. LOD for proline and arginine were 0.3 and 0.5 nM, respectively323. 

Reilly, J., and Saeed, M. (1998). Capillary electrochromatography as an alternative separation technique to high-performance liquid chromatography and capillary zone electrophoresis for the determination of drug related impurities in Lilly compound LY300164. /. Chromatogr. A 829, 175-186. 

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. 

Cloud point extraction has been applied to the separation and preconcentration of analytes including metal ions, pesticides, fungicides, and proteins from different matrices prior to the determination of the analyte by techniques such as atomic absorption, gas chromatography, high performance liquid chromatography, capillary zone electrophoresis, etc. 

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