Functionalised CuO nanostructures for the detection of organophosphorus pesticides: A non-enzymatic inhibition approach coupled with nano-scale electrode engineering to improve electrode sensitivity

Abstract

This study explores the potential of a newly-developed indium tin oxide (ITO) based electrode for the development of an electro-catalytic inhibition sensor system for organophosphorus pesticides. The sensor relies on the redox signal inhibition of pralidoxime chloride (PAM) immobilised over the pimelic acid functionalised CuO nanostructures grown in-situ over an ITO substrate. The in-situ growth enabled on-pot modification and functionalisation of ITO electrodes with the formation of uniform nanostructures possessing high surface area and excellent interface contact. The versatility of the proposed electrode was evident from its excellent electrochemical characteristics evaluated in comparison to bare and slurry-driven glassy carbon electrodes (GCEs). The high structural uniformity and greater surface coverage achieved by in-situ growth provided a uniform surface environment for electrode-analyte interaction, leading to good inhibition signal sensitivity and repeatability. The developed sensor was successful in detecting chlorpyrifos, fenthion and methyl parathion within the concentration range of 0.01-0.16 mu M with signal sensitivity reaching down to 1.6 x 10(-9), 2.5 x 10(-9) and 6.7 x 10(-9) M respectively. Moreover, the proposed sensor demonstrated excellent applicability when tested for chlorpyrifos from vegetable extracts using a standard addition method. (c) 2018 Elsevier B.V. All rights reserved.