Quantitative screening of carbamic and organophosphate pesticides mixture in extra virgin olive oil by acetylcholinesterase-choline oxidase sensor.

Abstract: Acetylcholinesterase-choline oxidase amperometric bi-enzymatic biosensor in a flow injection configuration has beenassembled in order to quantitatively detect carbamic and organoposphourus pesticides mixture in extra virgin olive oil samples. Therecognition of the two different pesticide classes by this biosensor has been carried out by exploiting the well-known differentinhibition mechanism of carbamic (reversible inhibition) and organoposphourus (irreversible inhibition) compounds versusacetylcholinesterase activity. In order to eliminate extraction clean-up steps for pesticides detection in extra virgin olive oil, inhibitioncalibration curves and analyses of spiked real samples were performed using hexan as the carrier in the flow injection apparatus. Theresults of the calibration curves showed a different inhibition power versus acetyl cholinesterase in function of the specific compoundand found that a probable interaction exists between two or more compounds that affected the toxic power of the single pesticide. Thelimit of detection (5?g·L-1) obtained for the tested organoposphourus (Paraoxon; Fenitrothion) and carbamic (Methomyl; Carbaryl) pesticides was lower than residues established by European legislation, thus suggesting that the bi-enzymatic biosensor, extensivelydescribed in literature, can be useful and economically convenient for quantitative screening methods in food security monitoring