Colourimetric Determination of Pharmaceutical Thiocompounds and Allopurinol Using Mercurochrome

Abstract
A new, simple and sensitive colourimetric method for determination of three pharmaceutical thiocompounds: cimetidine, thiabendazole and carbimazole, and also allopurinol, has been presented. the method is based on the reaction of each drug with mercurochrome (MER) in aqueous alkaline medium to give an intense red coloured chromogen. Optimization of the reaction conditions has been investigated. Obedience to Beer's law permitted the successful application of the proposed method for the assay of the investigated drugs in different dosage forms. Compared with the Pharmacopoeial methods, the proposed method gave equally accurate (t-test) and precise (F-test) results.