Abstract: A method for quantitative determination of total polysulfide content (TPsC) and reactive polysulfide content (RPsC) includes a step of using liquid chromatography-electrospray ionization-tandem mass spectrometry.

Abstract: A method for identifying active sulfur, including: a step of labeling active sulfur in a sample with an alkylating agent; a step of adding a reducing agent to a portion of liquid extracted in the first step to decompose active sulfur; a step of applying the sample subjected to reduction treatment and the sample not subjected to reduction treatment after the labeling to an analyzer, comparing results of analysis of both samples, and determining components of signals disappeared by the reduction treatment as candidates for the active sulfur in the sample; a step of confirmation that the signals are derived from the alkylating agent; and a step of, after the confirmation, extraction and purification of the components of the signals from the sample, and performing structural analysis of the components.

Abstract: The present invention is a new tyrosine derivative described below to inhibit hydrolysis of polysulfide. The new tyrosine derivative formed according to a chemical formula indicated below, wherein one of a-c is “OH” and the rest are “H”; d is CnH2n?, where ? is “H” or a “halogen atom,” the halogen atom is preferably “I,” and n is an integer from 1 to 5; and e is (NH)x(CO)yCzH2z?, where x is 1 or 0, y is 1 or 0, z is an integer from 1 to 5, ? is “H” or a “halogen atom,”.