A quantitative determination of organophosphate pesticides in organic solvents

An amperometric acetylcholinesterase (AChE) biosensor based on thiocholinehexacyanoferrate 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.