Novel Visible Spectrophotometric Method for Determination of Few Selected Drugs using Cobalt Thiocyanate as Chromogenic ReagentAuthor(s): G. Tuljarani, D. Gowri Sankar, P. Kadgapathi and B. Satyanarayana
A new, simple, accurate and economical spectrophotometric method for the determination of benzapril hydrochloride, quinapril hydrochloride, ranitidine hydrochloride, and drotaverine hydrochloride by using cobalt thiocyanate has been developed. The colored complexes are formed by coordination of secondary/tertiary amine group of drug with metal of cobalt thiocyanate that is extractable into nitrobenzene from aqueous solution. All the chromogens exhibit maximum absorption at 626 nm and obey Beer’s law in the concentration range of 100-500, 10-50, 25-175 and 50-300 µg/mL for benzapril hydrochloride, quinapril hydrochloride, ranitidine hydrochloride and drotaverine hydrochloride, respectively. The method was validated in terms of accuracy, precision, and specificity and can be used for routine analysis of these drugs in bulk and pharmaceutical dosage forms.