Determination of phenprocoumon in plasma and urine using at-line solid-phase extraction capillary electrophoresis

The use of capillary electrophoresis (CE) for the analysis of biological sa mples is rather problematic because of the large number of interferences pr esent in the matrix. One of the possibilities to solve such problems is to couple solid-phase extraction (SPE) at-line with CE, a technique developed in our laboratory. In this study at-line SPE-CE is performed for the determ ination of the anticoagulant phenprocoumon in biological fluids. Plasma sam ples are injected after the addition of 1 vol.% of formic acid to release t he drug from binding proteins, while urine samples can be directly injected . The procedure is linear between 0.2 and 30 mu g ml(-1) with a correlation coefficient, r(2), of 0.9996. The detection limit in plasma is 0.1 mu g ml (-1), which is fully adequate in view of the concentrations, that have to b e dealt with in practice. The phenprocoumon concentration in a plasma sampl e of a patient treated with the anticoagulant was 3.8 mu g ml(-1). (C) 1998 Elsevier Science B.V. All rights reserved.