Abstract:
There are a large number of life threatening problems due to the excessive use of
organophosphate pesticides. Acetylcholinesterase is inhibited by these organophosphate
pesticides whose function is to destroy acetylcholine after transmission of signals in the body. So
for their detection scientists are working on different methods. Various sensing techniques such
as NMR, IR, MS (mass spectroscopy) and gas chromatography are being used to sense different
organophosphates with high sensitivity, selectivity and reliability. As electrochemical sensing is
cost effective, gives quick response and easy to analyze so it is mostly used for the detection of
organophosphates. The nature of sensing materials used on the electrode depends on the nature
of analyte.
I have synthesized many compounds including GO using modified Hummers method, RGO by
chemical reduction with hydrazine hydrate and PGr by liquid phase exfoliation using NMP as a
solvent. I have also synthesized different types of materials like TPP by Adler Longo method,
Zn-TPP simply by metallation of TPP, THPP using a modification of Adler Longo method, Zn-
THPP by metallation of THPP. Then I have synthesized composites of RGO and PGr with TPP,
Zn-TPP, THPP, and Zn-THPP for the detection of dimethyl methylphosphonate (DMMP). The
synthesized materials were characterized by different techniques like FTIR, UV/Vis, NMR, XRD
and SEM. The electrochemical sensing of these compounds is done by using CV and EIS. Peak
current increased and resistance decreased as we increase the concentration. RGO/Zn-THPP 1:1
displayed best results because it shows highest peak current as compared to all other composites
and also show lowest resistance among all other composites. LOD and LOQ were calculated out
to be 0.0285 mM and 0.0950 mM. I have also checked the repeatability, reproducibility and pH
effect of RGO/Zn-THPP 1:1. It is concluded that RGO/Zn-THPP 1:1 is best among my
composites for the detection of DMMP.
