Spectrophotometric Method for the Determination of Some Drugs Using Fast Red B Salt

A simple spectrophorometric method for the determination of secnidazole, niclosamide, nifuroxazide and sulphasalzine is described. The method is based on reduction of the nitro group present in secnidazole and niclosamide molecule using zinc powder and dilute hydrochloric acid followed by reaction with fast red B salt in presence of ammonium chloride and sodium hydroxide, while in case of nifuroxazide and sulphasalazine the reaction takes place directly without any prior reduction between the phenolic group present in each drug and fast red B salt in presence of sodium hydroxide. Beer's law is valid in the concentration ranges 2.5-15, 1.25-10, 2.5-15, and 2.5-13.75 mu g.mL(-1) for secnidazole, niclosamide, nifuroxazide and sulphasalazine respectively. The proposed method is applied successfully for the estimation of the mentioned drugs either in pure form or in their pharmaceutical formulations.