Development of acid phosphatase based amperometric biosensors for the inhibitive determination of As(V).

An enzymatic amperometric procedure for the direct measurement of As(V) in the presence of As(III) was developed. The method is based on the inhibitive action of this species on acid phosphatase enzyme (AcP) activity. Screen-printed carbon electrodes (SPCEs) were used as support for the cross-linking immobilization of the enzyme AcP. 2-Phospho-l-ascorbic acid was used as a novel substrate, in arsenic determination, which amperometric response decreased by the presence of As(V) ions. The optimum working conditions were found using experimental design methodology. Under these conditions, repeatability and reproducibility of the constructed biosensors were determined, reaching values below 8% in terms of residual standard deviation. The capability of detection obtained for As(V) was 0.11 μM for AcP/SPCE biosensors. Analysis of the possible effect of the presence of foreign ions in the solution was performed. The method was successfully applied to the determination of the As(V) content in a ground water sample.