Validated stability-indicating HPLC method for the determination of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) and its degradation products

High-performance liquid chromatographic method was developed for the quantitative determination of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) and its degradation products. Forced degradation studies were performed on bulk sample of DDB using acid (1N hydrochloric acid), alkaline (0.1N sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (70 °C) and photolytic degradation. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to degradation products and the analyte was achieved on 5 μm ODS column (Luna, Phenomenex, USA). The mobile phase consists of a mixture of acetonitrile and water (60:40, v/v). Quantitation was achieved with UV detection at 235 nm based on peak area. The proposed HPLC method was utilized to investigate the kinetics of acidic, alkaline and oxidative degradation processes of DDB at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The pH-rate profiles of degradation of DDB in Britton-Robinson buffer solutions within the pH range 2-11 were studied. The developed method was validated with respect to linearity, accuracy, precision, robustness and forced degradation studies prove the stability-indicating power of the method.