Non-Enzymatic Sensing of Acephate as Model Organophosphate Based on Graphene/Tetraphenylporphyrin Nanocomposites Modified Glassy Carbon Electrode

Abstract

Extensive use of organophosphate pesticides has caused life threatening problems. They inhibits the acetylcholinesterase whose function is to destroy acetylcholine after transmission of signals. Scientists are working on different methods for their detection. Different sensing techniques including nuclear magnetic resonance, infrared spectroscopy, mass spectroscopy and gas chromatography are widely used for sensing of organophosphates with good reliability, sensitivity and selectivity. Electrochemical sensing has emerged as promising tool for detection and estimation of organophosphates because of its cost effectiveness, easy to analyze and quick response with accuracy. Different sensing materials are used over working electrode for detection of organophosphates depending upon the nature of analyte. I have synthesized GO, RGO and PGr based composites with tetraphenylporphyrin and Cutetraphenyl porphyrin for detection of acephate as model organophosphate. GO, RGO and PGr are synthesized by modified Hummers‘ method, chemical reduction by hydrazine hydrate and liquid phase exfoliation by using NMP as solvent respectively. TPP and CuTPP were prepared by using Adler Longo method and metallation of TPP respectively. Synthesis of materials was confirmed by UV-Vis spectroscopy, XRD, XPS, FTIR, NMR, SEM, EDS and Raman spectroscopy. Electrochemical sensing properties of composites were evaluated by using cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Decrease in the peak current and increase in resistance was obtained as the concentration is increased. RGO-CuTPP composite mixed in 1:0.5 was found to be the best sensing material because of highest peak current difference between blank and solution of acephate as compared to other composites. Linear response was obtained between 0.1 mM to 0.4 mM solution of acephate. RGO-CuTPP showed LOD of 0.054 mM and LOQ of 0.178 mM. It is concluded that these synthesized composites have potential to be used for detection of organophosphates in real samples.