Determination of adenosine deaminase activity in human erythrocytes by on-column capillary isotachophoresis capillary zone electrophoresis in the presence of electroosmotic flow

Transient capillary isotachophoresis (CITP)-capillary zone electrophoresis (CZE) in presence of electroosmotic flow (EOF) was utilized for the measure ment of adenosine deaminase activity in human erythrocytes. Phosphates, dom inant anions of the sample matrix, were used as leading ions for transient isotachophoresis, and berates (0.3 M, pH 10) were used as terminating ions and background electrolyte for CZE. Final experimental conditions made it p ossible to inject 70% of the total capillary volume (1.45 mu L) with the sa mple. Enzymatic conversion products (inosine and hypoxanthine), present in the sample in the low-micromolar range, were determined using optimized con ditions. The limit of detection was 28 nm using UV detection at 202 nm. The presented data shows that CITP-CZE can be performed in uncoated capillarie s in the presence of strong EOF.