New spectrophotmetric methods for determination of cephapirine Na

Three sensitive and accurate spectrophotometric procedures were developed for the analysis of cephapirine sodium in pure form and in its pharmaceutical formulation. Method A: A kinetic method based on the observation that in acidic medium cephapirine reduces sodium molybdate to molybdenum blue, the absorbance of which is proportional to the amount of antibiotic present at a fixed time of 40 minutes; the formed product was spectrophotometrically measured at 780 nm. The concentration of drug calculated using its calibration by fixed concentration and rate constant methods is feasible with the calibration equations obtained, but the fixed time method proved to be more applicable. Method B is based on chetale formation with palladium(II) chloride in buffered medium as the interaction between metal ions and ligand anions or moleules capable of the formation of complexes which results in the development of colors suitable for the characterization of quantitative determination of metal or ligand. Metals containing easily excited d or f electrons were suitable for the formation of colored complexes. Method C, is based on the formation of colored complex between palladium(II), eosin and cephapirine Na. Sodium lauryl sulphate is used as surfactant to increase the solubility and intensity of the formed complex. Under optimum conditions, the complexes showed maximum absorption at lambda 370 and lambda 550 for methods B and C, respectively. Apparent molar absorpitivities were 5.2 x 103 5.5 X 10(3), 1.4 x 10(4); Sandell's sensitivities were 1.17 x 10, 1.24 x 10(-3) 3.1 X 10(-3), for methods A, B and C, respectively. The solution of the products obeyed Beer's Law in the concentration ranges 10-70, 20-70, 2-48, mu g mL(-1) for methods A, B, and C. The proposed methods were applied to the determination of the drug in pure or pharmaceutical preparations. The results obtained were compared statistically with those given by the official method.