UV/Visible Spectroscopic Quantification of Veterinary Anthelmintic Drug Oxfendazole in Pharmaceuticals

Oxfendazole (OFA) is a broad spectrum benzimidazole anthelmintic medication used to treat veterinary diseases. Two new, simple, rapid, precise and accurate, and sensitive spectrophotometric methods have been developed and validated for the assay of OFA in its pure form and in its boluses. The first method (method A) is based on the measurement of green colored manganate obtained due to oxidation of OFA by permanganate in an alkaline medium at 610 nm. In the second method (Method B), the chromophoric activity of OFA is measured at 290 nm in the acetic acid–water (1:1) solvent system. OFA has been quantified over the linear ranges of 1.25–12.5 and 1.25–10 μg/mL in method A and method B, respectively, with apparent molar absorptivity values of 2.54 × 104 and 2.13 × 104 L·mol–1·cm–1. The limit of detection (LOD), limit of quantification (LOQ), and Sandell sensitivity values are 0.15 u 0.18 μg/mL, 0.46 and 0.56 μg/mL, and 0.0124 and 0.0148 μg/cm2. The developed methods were successfully applied to determine OFA in the bolus. No interference from adjuvants was observed.