Quantification of Hydrogen Sulfide and Methanethiol and the Study of Their Scavenging by Biocides of the Isothiazolone Family.

A sensitive analytical method for the quantification of malodourous hydrogen sulfide (H2 S) and methanethiol (CH3 SH) was developed and validated. The method consisted of solid-phase microextraction with concomitant in-fibre derivatisation of the mercaptan using N-ethylmaleimide. The adducts were analysed by GC-MS using a triple quadrupole in the selected reaction monitoring mode. The limits of detection of solutions of H2 S and CH3 SH in water were 100 and 10 ng L-1 , respectively, below their odour-perception thresholds. The analytical method was used to show the scavenging effect of 1,2-benzisothiazol-3(2H)-one (Proxel) and 2-methyl-4-isothiazolinone. The mechanism by which H2 S and CH3 SH are trapped with Proxel was studied by ultraperformance liquid chromatography (UPLC)-MS.