Development for the measurement of serum thiosulfate using LC–MS/MS in forensic diagnosis of H2S poisoning

[Display omitted] •Thiosulfate measurement is crucial to diagnosis of H2S poisoning in forensic toxicology.•This study presents a new method for the quantitative analysis of serum thiosulfate using LC–MS/MS.•Our method for the measurement of serum thiosulfate requires no complicated sample preparation.•Precision and accuracy of this method meet the basic requirements for quantitative analysis. Thiosulfate measurement is crucial to diagnosis of hydrogen sulfide (H2S) poisoning in forensic toxicology. Although GC–MS method is currently regarded as a standard thiosulfate measurement, it requires complicated sample preparation prior to analysis. This study presents a simple, rapid, and highly sensitive method for the quantitative analysis of serum thiosulfate by using liquid chromatography–tandem mass spectrometry (LC–MS/MS). This method is based on selected reaction monitoring and has high sensitivity with a lower quantification limit of 0.5μM. Precision and accuracy of this method meet the basic requirements for quantitative analysis (intra- and inter-day tests have a relative standard deviation of ⩽10.4%; range of analytical recovery is 94.3–102.6%). On the measurements of serum thiosulfate by our developed method, a thiosulfate concentration as 57.5μM was detected clearly in the H2S poisoning case comparing to the non poisoning case in which only a trace amount of thiosulfate was observed.