APPLICATION OF THE ZERO-CROSSING DERIVATIVE SPECTROPHOTOMETRY TO THE DETERMINATION OF CEPHRADINE AND CLAVULANIC ACID IN BINARY-MIXTURES

Derivative spectrophotometry, on the basis of the zero-crossing measurements in the first derivative spectra, is used for the resolution of the binary mixtures of cephradine (CED) and clavulanic acid (CA). Neither sample pretreatment nor any separation step were required. Linear calibration graphs of first derivative values at 277.0 and 235.5 nm for cephradine and clavulanic acid, respectively, with negligible intercept on the y-axis were obtained versus concentration in the range of 2.0-56.0 mu g mL(-1) for cephradine and 2.0-28.0 mu g mL(-1) for clavulanic acid. The detection limits for cephradine and clavulanic acid at a 0.05 level of significance, were 0.16 and 0.17 mu g mL(-1), respectively. The proposed method has been applied to determine these drugs in mixtures. Injectable dosages forms of cephradine and standard clavulanic acid were mixed and determined in saline physiological serum and physiological serum containing glucose.