XANTHINE ANALYSIS IN BIOLOGICAL-FLUIDS BY CAPILLARY ELECTROPHORESIS

Xanthine, a precursor of uric acid, is measured here in serum, urine, and cerebrospinal fluids by capillary electrophoresis (CE) after depro teinization with acetonitrile. The migration time is about 7.5 min wit h a minimum detection limit of 0.4 mg/l. Different purines and pyrimid ines did not interfere with the determination. The method demonstrates the suitability of the CE for determination of small molecules presen t in a complex matrix at levels of ca. 1 mg/l. It also demonstrates th at acetonitrile deproteinization is a simple and effective method for preparing samples for CE, allowing a large volume to be introduced int o the capillary.