High performance liquid chromatography (HPLC)
We are seeing a similar development in the field of capillary electrophoresis(CE).The development in CE of capillary pre-treatment procedures and permanent coatings is similar to developments in chromatography decades ago.Research in CE-in its present form with fused-silica columns and on-column detection-is more than a decade old (Jorgenson and Lukacs, 1981, 1983), and commercial CE instruments have been available since 1988.
The field is moving rapidly, illustrated by the fact that already six annual symposia on CE have been held and a number of comprehensive textbooks (see, for example, the textbooks edited by Camillieri, 1993; Landers, 1994; and Guzman, 1993)have been published recently. The reviews by Karger (1993) and Landers et al. (1993) capture the state of the art of CE. A sampling of the type of proteinrelated applications for which CE has been utilized in analytical biochemistry and clinical/diagnostic assays is given below.
As in HPLC, various separation modes are applicable to the analysis ofproteins and peptides: capillary zone electrophoresis(CZE), micellarelectrokineticcapillary chromatography (MECC), capillary isoelectric focusing(CIEF), capillary gel electrophoresis (CGE), and displacement electrophoresisor isotachophoresis (ITP).
While in CE, the separation of small peptides(in the CZE mode) often is relatively straightforward and well understood, it appears that no single strategy is applicable for large peptides and proteins.As might be expected, this is largely due to the wide diversity and complexity associated with these bio-molecules.
Thus, different strategies often work for different protein separation problems, hence requiring different CE separation modes.