Manganese Phthalocyanine as a Biomimetic Electrocatalyst for Phenols in the Development of an Amperometric Sensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The construction of an amperometric sensor for phenolic compounds using a carbon paste electrode modified with manganese phthalocyanine and histidine is reported. Under optimized conditions, at 0 mV vs Ag/AgCl in 0.1 mol dm(-3) phosphate buffer solutions (pH 7.0) containing 250 mu mol dm(-3) H2O2, a linear response for catechol from 20 up to 130 mu mol dm(-3) was obtained with a sensitivity of 0.56 (+/- 0.02) mu A dm(3) mu mol(-1) cm(-2). The detection limit was 1.1 mu mol dm(-3) and the response time was 2 s. The sensor presented stable response during 40 successive determinations. The repeatability, evaluated in terms of relative standard deviation, was 3.6% for n = 5 and [catechol] = 10 mu mol dm(-3). The sensor responses for other phenolic compounds were also investigated in details. Finally, the applicability of the sensor was tested in a pharmaceutical containing dopamine and the results compared favorably with those obtained with the official method.