Highly Reliable Impedimetric Sensor Based on Silver Nanoparticle-Functionalized Composites of Graphene Oxide and Ionic Liquid for the Detection of Trace Levels of the Pesticide Malathion

Abstract

Malathion (MLT), a widely used organophosphate pesticide for global pest control, presents substantial risks to both human health and ecosystems. Therefore, the development of a rapid and efficient detection method is critical to mitigate its harmful effects. This study proposes a novel thin-film impedimetric sensor designed for the reliable detection of MLT pesticide residues based on laser-induced graphene electrodes coated with a sensing composite material comprising graphene oxide, 1-butyl-3-methylimidazolium hexafluorophosphate, and silver nanoparticles. Mechanical and electrochemical stabilities are enhanced by the integration of polyvinyl chloride (PVC) and 2-nitrophenyl octyl ether (o-NPOE) into framework materials. The sensor exhibited excellent sensitivity toward MLT in the concentration range of 1 – 200 nm. The charge transfer resistance R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ct</sub> increases by 304.08% at a concentration of 200 nm. The sensor shows minimal interference and good reproducibility and repeatability. A change in R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ct</sub> of 15.61% over 30 days confirms good stability. Using framework materials enhances the long-term stability by 11.45 times compared to sensors without them. The synergistic effects of the three sensitive materials and the structural support from PVC and o-NPOE enable outstanding detection capabilities. The novel sensor has a high potential for pesticide residue detection in the environment, providing a reliable and efficient tool for preserving ecosystems, supporting sustainable agriculture, and ensuring compliance with environmental regulations.

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