Development of an enzymeless biosensor for the determination of phenolic compounds

The construction of amperometric enzymeless biosensors for phenolic compounds determination, using carbon paste electrode modified with copper phtalocyanine (CuPc) and histidine (His), based on the chemistry of the dopamine β-monooxygenase (DβM) enzyme that catalyzes the hydroxylation of the dopamine and its analogs is shown. The modified carbon paste was evaluated on electrodes constructed in two ways: putting the paste into a cavity of a rotating disk electrode and a platinum slide electrode fixed into a glass tube. The sensor in hydrodynamic conditions presented a linear response range between 30 and 250 μmol l^-1, with a sensitivity of 4.6±0.1 nA l μmol^-1 cm^-2 for catechol, response time of 3 s and lifetime of about 50 days when stored at room temperature. The sensor in static conditions showed a linear response range from 40 to 250 μmol l^-1, with a sensitivity of 0.30±0.01 nA l μmol^-1 cm^-2 for catechol. The sensors presented the following relative response order for dopamine and some analog species: catechol>dopamine>guaiacol>serotonin>phenol.