Pteridine analysis in urine by capillary electrophoresis using laser-induced fluorescence detection

Pteridines are a class of compounds excreted in urine, the levels of which are found to elevate significantly in tumor-related diseases. For the first time, we have developed a method, based on high-performance capillary elec trophoresis (HPCE) and laser-induced fluorescence (LIF)-detection, to monit or the pteridine levels in urine. HPCE provides better separation than high -performance liquid chromatography and the LIF detector enables us to detec t minute amounts of pteridines in body fluid, Eight different pteridine der ivatives were well separated in 0.1 M Tris-0.1 M borate-2 mM EDTA buffer (p H 8.75) using a 60-cm fused-silica capillary (50-mu m i.d., 35-cm effective length), six of which were detected and characterized in urine samples fro m normal persons and different cancer patients. The detection Emits of thes e pteridines are under 1 x 10(-10) M. The levels of neopterint pterine, xan thopterin, and pterin-6-carboxylic acid were found to be significantly elev ated in urine excreted by cancer patents, while the level of isoxanthopteri n dropped in these patients. No significant change of biopterin level was f ound between healthy individuals and cancer patients. This method can be us ed in clinical laboratories either for cancer monitoring or for precancer s creening.