Dynamically coated capillaries improve the identification power of capillary zone electrophoresis for basic drugs in toxicological analysis

In systematic toxicological analysis (STA), analytical methods should have a high identification power. This can be suitably expressed by parameters s uch as mean list length (MLL) or discriminating power (DP). The reproducibi lity of a method has a great impact on its identification power, and should be as high as possible. In this study, two separation methods based on cap illary zone electrophoresis (CZE) were evaluated towards STA applications. Besides a normal phosphate buffer, the commercially available buffer CElixi r was used, which is a double-layer dynamic coating system. The coating sta bilizes the endoosmotic flow, is independent of the pH, and is claimed to b e more reproducible and faster at low pH than with normal buffers. A test s et of 73 basic pharmaceutical compounds was analyzed by the two CZE methods . The total analysis time, including rinsing steps, was 8 min when the coat ing was used and 18 min without the coating. Effective mobilities were calc ulated and the reproducibilities were a factor of 2 better when the coating was used (between-days SD 0.020 and 0.040 m(2)/VS with and without the coa ting, respectively). MLL and DP were calculated for the two CZE methods and for combinations with standardized liquid and gas chromatography systems. CZE with CElixir coating clearly has a high potential for STA applications, as it was shown to have a higher identification power and shorter analysis times than normal CZE. (C) 2001 Elsevier Science B.V. All rights reserved.