Selective inhibition-based biosensing system for the determination of pesticides in environmental samples using analytical pervaporation coupled with enzymatic derivatisation

Abstract

A novel and selective method based on inhibition reactions coupled with a prior separation step consisting of analytical pervaporation has been designed and used in order to develop a method for the determination of diclorvos. The method is based on the inhibitory effect of this organophosphorous pesticide (low boiling point 35°C) on the acetylcholinesterase catalysis after selective pervaporation of the analyte. The derivatisation reaction is a two-step reaction involving choline oxidase (ChOD) and horseradish peroxidase (POD) with fluorimetric detection at λ ex=310 nm and λ em=415 nm of the dimer formed. The method applied to liquid samples has a linear determination range of 0.05–0.5 mmol l −1 ( n=8, r 2=0.9959) with excellent precision (RSD<3.2%) and a sampling frequency of 3 h −1. When applied to solid samples the method has a linear determination range of 0.001–0.04 g kg −1 ( n=5, r 2=0.9909, RSD<4.2%) and a sampling frequency of 2 h −1. The approach has been applied to the determination of diclorvos in natural water and spiked soil samples with recoveries between 89.9 and 109.7%.