4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole is a reagent used in the determination of aldehydes and other reactive chemicals.was used in purpald assay for determination of bacterial polysaccharides containing substituted or unsubstituted glycol in residues such as glycerol, ribitol, arabinitol, furanosyl galactose and sialic acid. It was used as chromogen during the determination of catalase activity in small tissue samples. It was used as reagent in determination of formaldehyde. It was used for derivatization of neutral monosaccharides during HPLC.