Spectrophotometric methods for the determination of some thiols with aminophenols and iron(III)

Abstract

Two spectrophotometric methods have been developed for the determination of thiols by use of two pairs of reagents, p-aminophenol (PAP)-Fe(III) for cysteine, cystamine hydrochloride, glutathione, β-mercapto-propionic acid, β-mercaptoethanol, thioglycolic acid, thiomalic acid and thiosalicylic acid and Metol [p-(methylamino)phenol sulphate]-Fe(III) for the above plus p-aminothiophenol, o-aminothiophenol and thiobarbituric acid. The methods are simple, sensitive, reproducible and accurate to within ±1.5% and have been applied to the assay of cystine after reduction and cystine in groundnut protein.