SPECTROPHOTOMETERIC DETERMINATION OF SOME CEPHALOSPORINS IN PHARMACEUTICAL FORMULATIONS

A simple and sensitive spectrophotometric method is described for the determination of cefadroxil, cefotaxime and ceftriaxone in pure form and pharmaceutical formulations. The method is based on reacting these drugs with iron(III) nitrate to form iron(II) which reacts with potassium hexacyanoferrate(III) forming a blue colored complex measurable spectrophotometrically at 777 nm. Maximum color formation was obtained through heating. Linearity was in the rang 0.6-10.0 μg ml^-1, 0.1- 8.0 μg ml^-1 and 0.1-3.0 μg ml^-1 for cefadroxil, cefotaxime and ceftriaxone, respectively with limits of detection of 0.1 μg ml^-1 for cefadroxil and 0.05 μg ml^-1 for the other two drugs. Linear response was observed over the tested range of each drug with correlation coefficient (r) 0.999 (n = 8-9). The mean relative standard deviation (RSD %) of the results of within day precision and accuracy of them were ≤1.1% which confirmed the reproducibility of the assay technique. The method results showed insignificant difference with those of reference methods. The method was successfully applied to the determination of these drugs in their dosage forms.