Electrochemical behavior and determination of amiloride drug in bulk form and pharmaceutical formulation at mercury electrodes

Abstract

The polarographic behavior of amiloride hydrochloride has been studied in Britton–Robinson buffers of pH 1.9–11. In acidic medium at pH≤2, the dc-polarograms exhibited a single 4-electron cathodic irreversible wave, while at pH values >2, a second two-electron irreversible cathodic wave appeared at a more negative potential. The single or first wave may be attributed to the cleavage of the double bond of the CHNH of the imidino amide group with the release of NH3. While the second wave may be due to the saturation of the CO of the carboxamide moiety. A polarographic procedure of suffocate sensitivity for the determination of bulk amiloride drug in Britton–Robinson buffer at pH 2 is described. The calibration graph was obtained over the concentration range 2.5×10−5to2.5×10−4M amiloride. The limits of detection (LOD) and quantitation (LOQ) of the procedure were 1×10−5 and 3.3×10−4M bulk amiloride, respectively. Moreover, a differential-pulse adsorptive cathodic stripping voltammetric procedure has been described to assay of the drug at lower concentration levels. The optimal conditions were: Eacc=−0.9V, tacc=30s, scan rate=20mV, pulse-height=90mV and Britton–Robinson buffer of pH 8. The calibration graph was obtained over the concentration range 2×10−8to1×10−6M for bulk amiloride. Both procedures were successfully applied to the determination of amiloride in tablets without the necessity for sample pretreatment or any time-consuming extraction or evaporation steps prior to the drug analysis.