Development of square wave voltammetry method for the assessment of organophosphorus compound impact on the cholinesterase of pheretima with 2,6-dichloroindophenol as a redox indicator

A square wave voltammetry method was developed for the assessment of organophosphorus (OPs) compound impact on the cholinesterase of pheretima with 2,6-dichloroindophenol (2,6-DCIP) as a redox indicator. The substrate of acetylthiocholine is hydrolysed by the cholinesterase (ChE) from soil animal pheretima, and the produced thiocholine reacts with the 2,6-DCIP to give obvious shift of electrochemical signal. The inhibition of ChE was assessed by measuring the enzyme activity before and after incubating with parathion-methyl. The reduction peak current of 2,6-DCIP decreases with the time of enzymatical reaction. The ChE loses almost 32.74% activity after 10 min incubation with 1 ng mL−1 paraoxon and 54.62% with 10 μg mL−1 paraoxon, while the activity that corresponds to 100 μg mL−1 paraoxon was nearly completely inhibited. This method can be employed to assess the inhibition of ChE and investigate OPs impact on environmental animals.