Polarographic determination and aqueous potentiometric titration of cimetidine in tablets

A method is described which uses the direct current (dc) polarographic behavior of cimetidine in a strong acid solution to determine this compound. The diffusional characteristics of the reduction wave of cimetidine in 1M HCl (about -0.8 V vs SCE) are shown, and their analytical usefulness was studied. This polarographic method was used to determine cimetidine in standard solutions ranging from 4 to 80 micrograms/mL with a coefficient of variation of 1.3%, and was further applied to the determination of cimetidine in tablets. The results obtained by the dc polarographic method agree with those obtained by an aqueous potentiometric titration of cimetidine with HClO4 and estimation of the end point by the Gran graphic method.