Enzyme-free electrochemical detection of nanomolar levels of the organophosphorus pesticide paraoxon-ethyl by using a poly(N-isopropyl acrylamide)-chitosan microgel decorated with palladium nanoparticles

A rapid voltammetric method is described for the determination of the organophosphorus pesticide paraoxon-ethyl (PEL). A glassy carbon electrode (GCE) was modified with a composite consisting of a poly(N-isopropylacrylamide)-chitosan microgel with incorporated palladium nanoparticles. The microgel was characterized by FE-SEM, EDX, XPS, FTIR, XRD, and EIS. The modified GCE is shown to enable direct electro-reductive determination of PEL by using differential pulse voltammetry. The method works in pH7 solution and in the 0.01M to 1.3mM PEL concentration range. At a typical working potential of -0.66V (vs. Ag/AgCl) (at50mV/s), the detection limit is as low as 0.7nM, and the electrochemical sensitivity is 1.60AM(-1)cm(-2). Intriguingly, the modified GCE displays good recovery when applied to bok choy and water samples.