ELECTROCHEMICAL OXIDATION OF SULFA DRUGS AT BORON-DOPED DIAMOND ELECTRODES

摘要

Conductive boron-doped chemical vapor-deposited diamond thin films have been found to be promising electrodes for the electroanalysis of sulfa drugs. Well-defined, scan rate-dependent cyclic voltammograms were obtained for three sulfa drugs, sulfadiazine, sulfamerazine and sulfamethazine, with a signal-to-background (S/B) ratio a factor of ten greater than that obtained at conventional glassy carbon electrodes. All of the drugs were oxidized at ～0.9 V vs. SCE. The pH dependence of the voltammograms indicated the deprotonation of the amine and amide groups of these compounds. Well defined, sigmoidally-shaped hydrodynamic voltammograms were obtained using the flow injection analysis technique with electrochemical detection (FIA-ED). Diamond exhibited highly reproducible amperometric response, with a variation of ～3%, even at a concentration of 100 nM. A detection limit of 50 nM with a three order magnitude of linear dynamic range were obtained. These results demonstrate the suitability of diamond for the electrochemical detection of sulfa drugs with high sensitivity.