A biosensor of graphite-epoxy resin-sweet potato tissue (source of polyphenol oxidase) was developed in this work. The evaluated compositions of graphite-epoxy resin-vegetable tissue were varied from 30 to 80% (m/m) graphite; from 5 to 60% (m/m) epoxy resin and from 5 to 20% (m/m) tissue. The cyclic and linear sweep voltammograms were obtained at a scan rate between 25 and 300 mV s-1 in the pH range from 3 to 8 in 0.1 mol L-1 phosphate buffer solutions. Several phenolic compounds were determined by the proposed biosensor and hydroquinone was determined in wastewater from photographic process. Relative standard deviations of 0.7% and 3.3% were obtained employing the same biosensor (n=10) and three different biosensors (n=10), respectively. Sensitivity and selectivity were evaluated employing the biosensor for hydroquinone with a lifetime of at least 6 months (more than 500 determinations).
composite biosensor; hydroquinone; sweet potato tissue; wastewater
