Determination of thiosulfate in human urine and plasma by high performance liquid chromatography with a dual electrochemical detector.

An analytical method for the determination of thiosulfate in human urine and plasma was established by high performance liquid chromatography (HPLC) with a dual electrochemical detector (DECD), the working electrodes of which were made of glassy carbon. Urine and plasma were pretreated with chloroform and SEP-PAK C18 cartridge, and the sample solutions were submitted to HPLC-DECD. Chromatographic conditions were as follows: column; TSK gel SAX (150 mm × 4 mm I.D.), eluent; 0.18 M NaNO3, flow rate; 1.1 ml/min, applied potential; W1 0.9 V vs. Ag/AgC1, W2 0.7 V vs. Ag/AgC1, sample size; 20 μl. A calibration curve for thiosulfate was linear in the range of 10 pmol to 4 nmol. The normal levels of thiosulfate in human urine and plasma were 31.2 ± 15.9 μmol/day and 2.68 ± 0.23 nmol/ml (mean ± SD, n = 5), respectively.