Stability-Indicating Methods for Determination of Flubendazole and Its Degradants

The resolution of flubendazole (FLB) and its degradants has been accomplished by using liquid chromatography (LC) using an octadecylsilane column and a mobile phase that consists of methanol and (0.1%) formic acid (75:25, v/v). Identification of FLB degradants was achieved with positive electron spray spectrometry detection. Furthermore, high-performance thin layer chromatography (HPTLC) separation was carried out using ethyl acetate:formic acid:acetic acid:water (9.5:0.11:0.11:0.28, v/v/v/v) as a mobile phase. Quantitation was achieved using densitometry at 254 nm. FLB was subjected to conditions of hydrolysis, photolysis, oxidation and thermal degradation. The proposed LC method determined that the kinetics of acidic and basic degradation followed a first-order kinetics, with an activation energy of 17.80 and 13.93 kcal mol(-1) for acidic and alkaline degradation processes, respectively. The pH-rate profiles of degradation of FLB in Britton-Robinson buffer solutions within the pH range (2-12) were studied. The developed methods were validated within the corresponding linear ranges of 3-30 µg mL(-1) with detection limits of 0.11 and 0.13 µg mL(-1) for FLB and DG1, respectively, for the high-performance liquid chromatography method and 10-65 and 5-30 µg band(-1) with detection limits of 0.22 and 0.30 µg band(-1) for FLB and DG1, respectively, for the HPTLC method.