A electrochemical biosensor for As(III) detection based on the catalytic activity of Alcaligenes faecalis immobilized on a gold nanoparticle-modified screen-printed carbon electrode.

A electrochemical biosensor for As(III) determination has been developed by immobilization of the Alcaligenis faecalis bacteria on gold nanoparticle-modified screen-printed carbon electrode (AuNPs-SPCE). The detection of As(III) is due to the catalytic activity of arsenite oxidase enzyme which oxidizes As(III) to As(V) producing an analytical signal. To enhance the performance of the biosensor, was optimized the amount of bacteria, amount of glutaraldehyde and incubation time applied in the preparation of the electrode, in addition to the effect of pH and applied potential. The analytical application was carried out applying 300 mV (pH = 7) obtaining a LOD of 6.61 μmol L-1 (R = 0.9975) and 700 mV (pH = 12) obtaining a LOD of 1.84 μmol L-1 (R = 0.9983). AF/AuNPs-SPCE was applied to the determination of total arsenic in Loa river water samples after reduction, with satisfactory results.