Quantitative determination method for reactive sulfur

Abstract

Provided is a quantitative determination method for sulfur compounds in a target group selected from a plurality of groups, e.g., a group including cysteine and related reactive sulfurs, including the steps of: performing an LC/MS/MS measurement of a standard substance having a known concentration of a base compound, e.g., cysteine, in the target group; acquiring quantitative reference information used for quantitative determination of the base compound and other reactive sulfurs, based on the measurement result, assuming that the signal intensities of sulfur compounds in the same group show a predetermined relationship when their concentrations are equal; performing an LC/MS/MS measurement for each sulfur compound in a specimen, under an analysis condition determined beforehand so that the signal intensities of sulfur compounds in the same group show the predetermined relationship when their concentrations are equal; and determining the quantity of each sulfur compound, using the measurement result and quantitative reference information.