The electrochemical oxidation and amperometric detection of catechols and catecholamines at boron-doped diamond thin-film electrodes

The electrochemical oxidation and amperometric detection of catechols and catecholamines was investigated using the new electrode material, diamond thin film. The films were synthesized by chemical vapor deposition and made electrically conducting by doping with boron. In general, diamond has properties superior to those of other commonly used carbon electrodes (e.g., glassy carbon), among which are low background current, good response precision, stable response without pretreatment, and high resistance to fouling. Cyclic voltammetric investigations were carried out to evaluate the electrode response for dopamine, catechol, and 3,4-dihydroxyphenylacetic acid as a function of the potential sweep rate and solution pH. The electrode performance for the amperometric detection of these and other catecholamines in flow injection analysis (FIA) and high performance liquid chromatography (HPLC) was evaluated in terms of linear dynamic range, limit of quantitation, sensitivity, and response precision. The mass limits of quantitation (S/N > 3) were 10--70 pg in FIA and 10--1200 pg in HPLC.{09}The figures of merit for untreated diamond are comparable to those of glassy carbon.{09}Diamond outperformed glassy carbon in terms of response stability and resistance to fouling. Finally, the bioanalytical applicability of the HPLC-EC assay was demonstrated.