“Zero-crossing” derivative spectrophotometric determination of mixtures of cephapirin sodium and cefuroxime sodium in pure form and in injections

Abstract

Two-component mixtures of cephapirin Na and cefuroxime Na were assayed by first- and second-derivative spectrophotometric methods using a “zero-crossing” technique of measurement. The relative ease offered by this technique for the quantification of these drugs with closely overlapping spectral bands was clearly demonstrated. Beer's law holds up to 40 µg ml^–1 for both cephalosporins. The detection limits of cephapirin Na and cefuroxime Na, at a 0.05 level of significance, were calculated to be 0.34 and 0.85 µg ml^–1, respectively, in the first-derivative mode and 0.37 and 0.64 µg ml^–1 in the second-derivative mode. The results of the determination of these antibiotics in mixtures of injectable dosage forms are also presented.