SPECTROPHOTOMETRIC ASSAY OF CEPHALOSPORINS IN PHARMACEUTICAL PRODUCTS, USING CHROMOTROPE 2B AND CHROMOTROPE 2R

A simple, rapid and sensitive spectrophotometric method is proposed fo r the determination of cephadroxil (I), cephalexin (II) and cephradine (III). The method is based on ion-pair complex formation between thes e derivatives and chromotrope 2B (C2B) or chromotrope 2R (C2R), to giv e a highly coloured radical anion. The coloured products are quantifie d spectrophotometrically at 542 and 564 nm for C2B and C2R, respective ly. The optimization of the experimental conditions is described. The method has been used for the determination of 0.4-15, 0.4-14 and 0.4-1 8 mu g/ml of drugs I, II and III, respectively. The accuracy of the me thod is indicated by the excellent recovery (100.0 +/- 1.7%) and the p recision is supported by the low relative standard deviations less tha n or equal to 1.5%. The sensitivity of the method is discussed and the results are compared with the official method. The interference from common degradation products and excipients was also studied. The propo sed method was applied successfully to the determination of the differ ent cephalosporins in dosage forms, with good precision and accuracy. The results were compared with those given by the official B.P. 1993 m ethod.