Titrimetric and spectrophotometric titration of some pharmaceutical important thiol compounds using 2,6-dichlorophenol-indophenol

ABSTRACT

Two procedures were adopted for determination of three pharmaceutical compounds containing thiol group; namely, D-penicillamine, N-acetylcysteine and captopril, by 2,6-dichlorophenol-indophenol [DCPIP]. In the first, the drugs are treated with a known and excessive volume of 1 x 10-3 M DCPIP and after 5 minutes the surplus is determined by titration with standard L-ascorbic acid. In the second, the drugs are titrated with 5 x 10-4 M solution of DCPIP with spectrophotometric end-point detection. The stoichiometry of the reaction is assumed and a reaction mechanism is suggested. The methods have been applied to the analysis of pharmaceutical preparation containing these drugs and the results obtained compared favorably with those from the pharmacopoeial methods. The methods are simple, accurate and precise