NOVEL METHODS FOR THE VISIBLE SPECTROPHOTOMETRIC DETERMINATION OF PIPAZETHATE HCl AND CHLORPHENOXAMINE HCl IN PURE AND TABLET DOSAGE FORMS

Three rapid, simple, precise and sensitive visible spectrophotometric methods (A-C) have been developed for the determination of pipazethate hydrochloride (PZ-HCl) and Chlorphenoxamine hydrochloride (CPA-HCl) in pure and Tablet Dosage Forms. Both methods (A-C) involves the formation of intense yellow ion-association complex between drug(s) and either of picric acid (PA) or phenol red (PR) or chlorophenol red (CPR) reagents followed by extraction with methylene chloride. The ion-associates exhibit absorption maxima at 359, 393 and 405 nm for PZ-HCl and at 357, 388 and 400 nm for CPA-HCl with PA, PR and CPR, respectively. The calibration curves resulting from the measurements of absorbance–concentration relations (at the optimum reaction conditions) of the extracted ion-association complexes are linear over the concentration range 3.05-43.60, 8.72-104.64 and 3.27-49.05 μg/mL for PZ-HCl and 3.40-47.64, 8.51-88.48 and 3.40-40.84 μg/mL for CPA-HCl with PA, PR and CPR, respectively. The molar absorptivities and Sandell’s sensitivities of the reaction products were calculated. In methods (A-C) the slope, intercept, correlation coefficient, relative standard deviation (RSD), detection and quantitation limits were also calculated. No interference was observed from common excipients present in pharmaceutical formulations. The results are well compared to those obtained by the reference methods using Students t- and F-tests. Therefore, the present methods are suitable for the drugs determination, as they are accurate and precise to a high extent.7