[Determination of human urinary pseudouridine by high performance capillary electrophoresis]

Pseudouridine, mainly as a degradation product of transfer ribonucleic acid, has been shown to be excreted in abnormal amounts in the urine of patients with cancer and can be used as one of the potentially valuable tumor markers. In this paper, a method for the rapid determination of human urinary pseudouridine by HPCE is reported. We used a 24 cm x 25 microm i.d. coated capillary and a borate buffer solution (0.1 mol/L, pH 8.6), and set the UV detection wavelength at 200 nm. In this experiment, pseudouridine can be separated completely with uridine and anti-tumor drugs (5-fluouridine and methetrexation) and other endogenous substances in urine within 4 minutes. Assay precision was determined for concentrations of 50 micromol/L and 200 micromol/L as 2.38% and 1.92% for within-day CV, 3.7% and 2.4% for between-day CV respectively. Sulfosalicylic acid was used as internal standard. Linearity, between the concentrations of pseudouridine and the corresponding peak height or area ratios of pseudouridine and the internal standard, was demonstrated in the 6.25-200 micromol/L range (r>0.9990). The detection limit of concentration for pseudouridine was 4 micromol/L. This method, with simple sample preparation, good assay precision, lower cost and full-automation, is an effective means for the assessment of pseudouridine in clinical application.