VALIDATED STABILITY-INDICATING HPTLC AND HPLC METHODS FOR DETERMINATION OF PIPAZETHATE AND ITS DEGRADANT

This paper describes validated high-performance thin-layer chromatography and high-performance liquid chromatography methods for the simultaneous determination of pipazethate hydrochloride (PZ) and its degradant. The HPTLC separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 as stationary phase using chloroform: diethylamine: methanol (9.4:0.1:0.5, v/v/v) as a mobile phase. Quantification was achieved using densitometric measurements at 225 nm. The isocratic reversed phase HPLC separation was performed on 5 mu m CN column (Luna, Phenomenex (R), USA.). Good resolution between PZ and its degradants was achieved using a mixture of acetonitrile: 12mM ammonium acetate: diethylamine (35:65:0.1, v/v/v, pH 4.0) as a mobile phase. Quantitation was achieved with UV detection at 225 nm based on peak area. Forced degradation studies were performed on bulk sample of PZ using acid (1N hydrochloric acid), alkaline (0.1N sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (75 degrees C), and photolytic degradation. The proposed HPLC method was utilized to investigate the kinetics of acidic, alkaline, and oxidative degradation processes of PZ at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. The pH-rate profile of degradation of PZ in Britton-Robinson buffer solutions within the pH range 1.8-11.4 was studied.