Rapid detection of organophosphorus pesticide residue on Prussian blue modified dual-channel screen-printed electrodes combing with portable potentiostat

A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode (DSPE) that was integrated with a portable smartphone-controlled potentiostat. The two carbon working channels of DSPE were first modified by electrodepositing of Prussian blue. The channels were then modified with acetylcholinesterase (AChE) via Nafion. The inhibition ratio of AChE was detected by comparing the electrical current of acetylthiocholine (ATCh) that was catalyzed by the enzyme electrodes with (channel 1) and without (channel 2) organophosphorus pesticide. Inhibition ratios were related with the negative logarithm of the organophosphorus pesticide (trichlorfon, oxamyl, and isocarbophos) concentrations at optimum experimental conditions (pH 6.9 of electrolyte, 0.2 V working potential, 2.5 μL AChE modification amount, and 15 min inhibition time). The linear equations were I% = 32.30lg C  + 253.3 ( R  = 0.9750) for isocarbophos, I% = 35.99lg C  + 270.1 ( R  = 0.9668) for chlorpyrifos, and I% = 33.70lg C  + 250.5 ( R  = 0.9606) for trichlorfon. The detection limits were calculated as 10 −7  g/mL. Given that the inhibition ratios were only related with pesticide concentration and not with pesticide species, the proposed electrodes and electrometer can rapidly detect universal organophosphorus pesticides and assess pesticide pollution.