High-voltage electrophoresis

The use of commercial capillary electrophoresis high-voltage power... 

Capillary Electrophoresis. Capillaries were first appHed as a support medium for electrophoresis in the early 1980s (44,45). The glass capillaries used are typically 20 to 200 p.m in diameter (46), may be filled with buffer or gel, and are frequendy coated on the inside. Capillaries are used because of the high surface-to-volume ratio which allows high voltages without heating effects. The only limitations associated with capillaries are limits of detection and clearance of sample components. 

The aqua ion Ir(H20) + and halide complexes IrX - have already been mentioned above. The kinetic inertness of the low spin d6 complexes means that hydrolysis of IrClg- is slow complexes up to IrCl2(H20)4 have been produced and separated from mixtures by high-voltage electrophoresis. 

Fujiwara, S. and Honda, S., Effect of addition of organic solvent on the separation of positional isomers in high-voltage capillary zone electrophoresis, Anal. Chem., 59, 487, 1987. 

Altria, K. D. and Simpson, C. F., Analysis of some pharmaceuticals by high voltage capillary zone electrophoresis, Pharm. Biomed. Anal., 6, 801, 1988. 

High-voltage electrophoresis and subsequent paper chromatography of the fractions obtained made possible the isolation from the analyzed mixture of twenty-two components giving colored spots with ninhydrin and isatin. Among these, fourteen were identified as peptides and their amino acid composition established (Table 5). In the case of eight peptides, also N- and C-terminal amino acids were determined (Table 6). 

A two-dimensional technique involving initial separation by high voltage electrophoresis at pH 2.0 followed by chromatography is a useful means of separating similar amino acids and short peptides and does not require desalting or excessive purification of the sample (Figure 10.17). 

Figure 10.17 Two-dimensional high voltage electrophoresis and chromatography of amino acids. Paper high voltage electrophoresis (4000 V) in an acetic acid-formic acid buffer at pH 2.0 in the first dimension followed by descending chromatography in the second dimension in an n-butanol-acetic acid-water solvent (12 3 5). The spots were visualized with a ninhydrin-collidine reagent.

A schematic representation of a CE system is presented in Figure 9.1. In this diagram, the CE components have obvious counterparts to those found in slab gel electrophoresis. Instead of buffer tanks there are two small buffer reservoirs, and the capillary takes the place of the gel (or more accurately, a gel lane). The capillary is immersed in the electrolyte-filled reservoirs, which also make contact with the electrodes connected to a high-voltage power supply. A new feature to the conventional gel electrophoresis format is the presence of an online detection system. 

Capillary electrophoresis (CE) instrument is quite simple. A CE, at its core, is merely a high-voltage power supply (capable of voltages in excess of 30,000 V), capillary (approximately 25 to 100 pm inner diameter), buffers to complete the circuit (e.g., citrate, phosphate, acetate, etc.), and a detector (e.g., UV-Vis). There are additional complexities, of course, but at its heart, the CE is a simple instrument. 

The study of natural Au in soil has been hampered by low concentrations, typically in the ppb range. Investigating the presence of metallic ions has been made more difficult with very few traditional techniques that may be used (e.g. polarography, high voltage electrophoresis and ion chromatography). At the low concentrations of Au in soil, these... 

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