Vanadophosphoric Acid as a Modified Reagent for the Spectrophotometric Determination of Certain Cephalosporins and their Dosage Forms

摘要

Vanadophosphoric acid in acidic medium is propsoed as a modified reagent for the spectrophotometric determination of cephalexin, cephaprin sodium, cefazolin sodium, and cefotaxime in pure sampes and in pharmaceutical preparations. The method is based on acid hydrolysis of cephalosporins and subsequent oxidation with vanadophosphoric acid. The resulting sodium exhibits maximum absorption at about 516 nm. The effects of reaction conditions were investigated. Lambert-Beer's law was obeyed over a concentration range of about 0.4-45 #mu#g ·cm~(-3). For more accurate results, Ringbom optimum concentration ranges were obtained, and the molar absorptivities and Sandell sensitivities were derived. The proposed method was applied to the determination of the drugs in pharamaceutical formations; the results demosntrated that the propsoed method is as accurate, pecise, and reproducible as the official methods.