Reduced graphene oxide nanosheets modified with nickel disulfide and curcumin nanoparticles for non-enzymatic electrochemical sensing of methyl parathion and 4-nitrophenol

A method was designed for simultaneous voltammetric determination of methyl parathion pesticide (MP) and 4-nitrophenol (4-NP). Curcumin nanoparticles were deposited on reduced graphene oxide nanosheets that were modified with nickel disulfide. The material was placed on a screen-printed carbon electrode and then displayed high electrocatalytic activities toward MP and 4-NP, with a peak potential near -0.9 and - 0.7 V (vs. pseudo Ag/AgCl), respectively. Figures of merit include (a) good electrochemical sensitivities (7.165 and 6.252 mu A center dot mu M-1 center dot cm(-2)), (b) wide linear ranges (from 0.25 to 80 mu M), (c) low limits of detection (8.7 and 6.9 nM at S/N = 3) for MP and 4-NP, respectively, and (d) good selectivity, repeatability, reproducibility, and storage stability. The method was applied in the determination of MP and 4-NP in tomato and apple juices and spiked river water.