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.
