Biosensor based on chitosan biopolymer and crude extract of ginger (Zingiber officinales rosc.) for the determination of hydroquinone in wastewater of photographic process

A new reagentless biosensor for differential pulse voltammetric detection of hydroquinone in the wastewater of the photographic process was developed. Crude extracts of several vegetables, such as arracacha, cassava, corn, ginger, guava, pineapple, swiss chard, and sweetsop were obtained as sources of peroxidase (PER; EC 1.11.1.7). Among them, a ginger crude extract was selected due to the highest specific activity observed after its immobilization by cross-linking with glutaraldehyde in a prepared chitosan matrix that was incorporated in a carbon paste electrode. In the presence of hydrogen peroxide, this enzyme catalyzes the oxidation of hydroquinone to o-quinone. The recovery of hydroquinone from the samples ranged from 98.4-105%, and a rectilinear analytical curve for hydroquinone concentration from 2.50 x 10(-4) to 2.40 x 10(-3) mol L-1 (r = 0.997) was obtained. The detection limit was 2.50 x 10(-5) mol L-1, and the relative standard deviation was lower than 1.2% for 4.95 x 10(-4) moI L-1 hydroquinone in 0.1 mol L-1 phosphate buffer solution at pH 7.0 (n = 10).