OPTIMUM CONDITIONS FOR PREPARATIVE OPERATION OF CAPILLARY ZONE ELECTROPHORESIS

The possibilities to use capillary zone electrophoresis (CZE) as a pre parative tool have been studied, mostly from a theoretical point of vi ew. The preparative performance of CZE is quantitated by the productio n rate, the amount of analyte that can be purified per unit of time. T he production rate available with CZE is shown to depend in the first place on the chemical characteristics of the analyte-buffer combinatio n. A figure of merit can be defined for a buffer system, describing it s susceptibility to analyte overloading. Methods to find an optimal bu ffer system are referred to. It is shown that the loadability of the s ystem is inversely proportional to the plate number required for the s eparation. A second important factor for the maximum production rate i s shown to be the thermal management of the instrumental system, The a verage increase of the solution temperature and the non-uniform migrat ion velocity by temperature differences within the solutions are discu ssed. It is shown that in practical cases the temperature rise of the solutions will be the main limiting factor when high fields are used. With low fields, which in general give a higher production rate, sipho ning of the solution becomes the dominant limitation for the productio n rate. With cylindrical capillaries the highest production rate that can be obtained under practical conditions is in the order of 5 . 10(- 13) mol s(-1). Experimental and theoretical results indicate that with rectangular capillaries the production rate can be increased by a fac tor of three.