Cyclic and linear sweep voltammetry of cefazolin and cefmetazole: electroanalytical applications

A study of the variables influencing the voltammetric behaviour of cephalosporins and cefamycins bearing substituents of the S-R' type (R' = non-electroactive group) has been carried out in order to determine the most suitable conditions for obtaining reproducible peaks for the determination of both types of antibiotic and the calculation of kinetic and thermodynamic parameters. The voltammetric behaviour of cefazolin and cefmetazole has also been studied. The voltammetric peak yielded by these two antibiotics at high sweep rates and low concentrations is due solely to the reduction of adsorbed molecules as the contribution of those molecules moving to the electrode through diffusion to the current is negligible. The peak current of cefazolin varies linearly with its concentration in the range 10(-9)-10(-7) M, whereas the linear range for cefmetazole is between 10(-8) and 5 X 10(-7) M, which allows the electroanalytical determination of the two antibiotics at these concentrations.