Electrochemical reduction and oxidation of two cephalosporin antibiotics: Ceftriaxone (rocephin) and cefoperazone (cefobid)

Two cephalosporin antibiotic derivatives, ceftriaxone (CFRX) and cefoperazone (CFPZ), have been studied by direct current, differential pulse polarography (DPP), and cyclic voltammetry. Both give rise to two irreversible two‐electron reduction steps. The characteristics of the corresponding electrode reactions are discussed. The electrooxidation of both drugs was also studied at the carbon paste electrode (CPE). Both drugs give rise to one oxidation peak at about +1.05 V vs. SCE (pH 1.6, phosphate buffer solution). Optimum pH ranges for the determination of these drugs at the CPE are also given. Linear calibration plots were obtained over the concentration ranges 0.49 to 99 μg/mL and 0.66 to 534 μg/mL for CFRX and CFPZ, respectively. Detection limits of 2.5 ng/mL and 0.13 μg/mL for CFRX and CFPZ, respectively, were readily achieved.