Determination of thiosulfate in human urine by high performance liquid chromatography

Thiosulfate is a sulfate analogue with a thiosulfur substituent and is found in human samples. Its concentration in urine is increased in some diseases and after exposure to hydrogen sulfide gas. We have developed a sensitive, simple and cheap method for thiosulfate determination in urine. The method is based on precolumn derivatization with 2-chloro-1-methylquinolinium tetrafluoroborate followed by reversed-phase liquid chromatography separation and ultraviolet detection of 1-methyl-2-thioquinolone at 375 nm. The calibration curve for thiosulfate was linear in the tested range 0.5–50 μmol L−1 with correlation coefficient better than 0.999. The analytical recovery and relative standard deviation values for precision within the calibration range were from 90.1% to 104.2% and from 2.39% to 5.59%, respectively. The lower limit of detection and quantitation were 0.3 and 0.5 μmol L−1, respectively. The mean (range) concentration of thiosulfate normalized against creatinine for apparently healthy seven women and six men was 2.21 (1.45–2.77) and 2.51 (1.36–4.89) mmol mol−1 creatinine, respectively. We monitored thiosulfate in urine samples from one volunteer for 24 h. The urinary excretion of thiosulfate was 21.4 μmol per 24 h. This method can be used for routine clinical monitoring thiosulfate in urine. Cysteine and cysteinylglycine can be measured concurrently, if needed.