?Iridium-Dispersed Enzimatic Carbon Paste Electrode for the Quantification of Phenols and Catechols?

M. D. RUBIANES AND G.A. RIVAS.

Bonn, Alemania

Conferencia; 8th International Conference on Electroanalysis; 2000

SEAC

In the last decade there has been great interest in the development of biosensors. The electrochemical biosensors, especially enzyrnatic ones, based on tl1e combination of the high specificity of biocatalytic processes with the advantages of the electrochemica transduction, have proved to be very usefil1 for the quantification of different metabolites. In the present communication an amperometric bioelectrode for the quantification of phenols and catechols of clinical, phannacological and environmental interest, based on the incorporation of iriditim microparticles and polyphenol oxidase (PPO) within carbon paste matrices, is described. The determinations were performed amperometrically in 0.050 M phosphate buffer(pH 7.40) at -0.100 Vas this potential allows us to obtain the best compromise ignal-to noise. Commercial enzyme and fresh banana tissue were employed for the measurements. The studied compounds were phenol, L-tyrosine, acetaminophen, catechol, L-dopa and dopamine. The effect of iridium and PPO content in the paste on the response of the bioelectrode is evaluated. The iridium-doped carbon paste electrode displays excellent electrocatalytic activity towards the reduction of the enzyrnatically formed quinone species. Thus, the quantification of the micromolar/submicromolar levels of phenols and catechols can be performed at potentials lower than in the case of bare CPE with much better sensitivity (around 4-fold higher). The analytical performance as well as the kinetic parameters for the different substrates, is evaluated.