Capillary electrophoresis as a clinical tool. Determination of organic anions in normal and uremic serum using photodiode-array detection.

We report the use of free solution capillary electrophoresis to identify and quantify low-molecular-mass compounds found in normal and uremic serum as well as in hemodialysate fluid. The method reported provides a multicomponent analysis, allowing a single-step screening for more than 19 metabolites in less than 16 min. Serum samples from healthy individuals and from patients who have been diagnosed with chronic renal failure are analyzed using a borate buffer system at pH 9.0, and an extended light path capillary. Several ionic sample constituents are identified by electrophoretic mobility, UV spectra, and spiking with authentic standards. An analysis of the relative concentration of several metabolites, including hypoxanthine, pseudouridine, hippuric acid, and uric acid is presented. Each of these four metabolites is found in both normal and uremic serum samples (limits of detection 1 to 6 microM). Moreover, each of these metabolites is present at significantly elevated levels in uremic patients. The method reported is shown to have promising clinical utility for profiling serum sample constituents, and for quantitative determination of a few important metabolites.