Stability-indicating spectrophotometric and densitometric methods for determination of some cephalosporins

Two methods were developed for determination of intact ceftazidime (I), cefuroxime sodium (II), and cefotaxime sodium (III) in the presence of their degradation products. In the first method, first derivative spectrophotometry (D-1) is used. The (D-1) absorbance is measured at 268.6, 306, and 228.6 nm for I, II, and III, respectively. The first proposed method determines I, II, and III in concentration ranges of 5-50, 5-35, and 5-40 mu g/mL, respectively, with corresponding mean accuracies of 99.7 +/- 0.8, 100.1 +/- 0.7, and 99.8 +/- 0.8%. The method determines the intact drug in the presence of up to 90% degradation products for I, and II and up to 80% far III. The second method depends on the quantitative densitometric evaluation of thin-layer chromatograms of I, II, and III. It determines I, II, and III in concentration ranges of 4-16 mu g for 1 and 2-12 mu g for II and III, with mean accuracy's of 99.5 +/- 0.8, 99.2 +/- 0.7, and 99.7 +/- 0.8% for I, II, and III, respectively. The second method retains its accuracy in the presence of up to 90% degradation products for the 3 drugs. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the official method.