A quantitative determination of organophosphate pesticides in organic solvents

An amperometric acetylcholinesterase (AChE) biosensor based on thiocholine-hexacyanoferrate reaction was developed for the analysis of OPCs in pure organic solvents. The enzyme (AChE) was co-immobilized with an electron mediator, Prussian Blue, on the surface of a graphite electrode. The effect of organic solvents on acetylcholinesterase activity was estimated in the presence of polar (hydrophilic) and non-polar (hydrophobic) organic solvents in the range of 0.01–100%. The ability of the AChE biosensor to detect pesticides was demonstrated by quantitative determination of dichlorvos, fenthion and diazinon in ethanol solvent. The assay allows determination of OPCs in sub-micromolar concentration ranges with an overall assay time of 10 minutes. The sensing elements of the amperometric AChE biosensor can be stored in dry state for more than 2 months. The AChE biosensor possesses distinct advantages, including monitoring of hydrophobic substrates, elimination of microbial contamination, and relative ease of enzyme immobilization. Potential application areas include food analysis and environmental monitoring.