Electrochemical characterization of cefadroxil β-lactam antibiotic and Cu(II) complex formation

The electrochemical behaviour of cefadroxil, a first-generation β-lactam antibiotic, was studied at glassy carbon electrodes in aqueous media over a wide range of pH. The first oxidation process is of the phenol moiety and follows an ECE mechanism, generating catechol and resorcinol derivatives as sub-products, which are then reduced and oxidized in subsequent cycles. The sulphur heteroatom present in the cyclic structure close to the β-lactam moiety is oxidized in two steps generating sulphoxide and sulphone. This process was identified from direct comparison with amoxicillin, which has a similar molecular structure, although they belong to different classes of β-lactam antibiotics. For amoxicillin, oxidation of the sulphur heteroatom occurred at more positive potentials, most likely due to structural difficulties in stabilizing the charged oxidized species. Formation of a complex between copper (II) and each of the antibiotics was studied by cyclic voltammetry. Finally, determination of cefadroxil in commercial samples was successfully carried out. •Electrochemical characterization of cefadroxil at glassy carbon in aqueous media•Oxidation of the phenol moiety by ECE mechanism generating catechol and resorcinol•Comparison between electrochemical profile of cefadroxil and amoxicillin•The phenol oxidation process was used to obtain a limit of detection of 0.3μM.•Phenol oxidation was used to measure the amount of cefadroxil in commercial samples.