Capillary isotachophoresis instrumentation

The separation unit of the capillary isotachophoresis instrument used is shown in Fig. 13.1. A 0.85mm id capillary tube made of fluorinated ethylene propylene copolymer was used in the pre-separation (first) stage and a capillary tube of 0.30mm id made of the same material served for the separation in the second stage. Both tubes were provided with conductivity detection cells [18] and an ac conductivity mode of detection [15] was used for making the separations visible. 

Capillary electrophoresis is the generic name for a family of related techniques which have their origin in capillary zone electrophoresis (CZE) and are capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), miscellar electrokinetic capillary chromatography (MECC) and capillary isotachophoresis (CITE). Though the techniques differ significantly in principle of operation they can be carried out largely on the same basic instrumentation. 

Figure 5 Configuration of capillary isotachophoresis. The arrangement shown is close to a real Instrument. The capillary is often made of plastic. The semipermeable membrane prevents electro-osmotic and hydrodynamic flows of the electrolyte but allows electromigration of ions. A conductivity detector is often used. It has miniature electrodes placed inside the capillary.

Capillary isotachophoresis began to develop as a modern instrumental analytical method at the end of the 1960s and the beginning of the 1970s and is now a well-established method with a good theoretical background and available commercial instrumentation directed nowadays toward miniaturization. It is... 

One of the major advantages of CE as a separation technique is the wide variety of separation modes available. Analytes can be separated on the basis of charge, molecular size or shape, pi, or hydrophobicity. The same CE instrument can be used for zone electrophoresis, IEF, sieving separations, isotachophoresis, and chromatographic techniques such as MEKC and capillary electrokinetic chromatography. This section provides a brief description of each separation mode. Zone electrophoresis, IEF, and sieving are the primary modes used for protein separations, and these will be discussed in detail in the following sections. 

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