Iodometric and spectrophotometric assays for cephradine after its hydrolysis with a β-lactamase

Iodometric and spectrophotometric methods were developed for the analysis of the new antibiotic cephradine. The procedures are modifications of known methods but are novel in employing a specific β-lactamase for hydrolysis of the β-lactam ring of the cephalosporin molecule. The iodometric method is rapid, precise, and accurate, but it requires fairly large amounts of cephradine. The spectrophotometric method, using differential UV absorption at 260 nm, is more rapid and more sensitive than the iodometric method but somewhat less accurate. Both methods proved useful for the routine assay of cephradine in certain formulations.