Abstract:
Different types of pesticides had been widely used during the last several decades to improve
the increasing demand of food production for ever increasing human population. The
widespread use of these pesticides, under the proverb, ―if little is good, a lot more will be
better‖ has wrecked the humans and other forms of life. Organophosphate pesticides are
acetylcholinesterase (neurotransmission regulating agent) inhibitors. Several techniques have
been established for detection of pesticides in food samples and environment over the last
decades. Electrochemical sensing has arisen as a promising tool for detection and estimation
of organophosphates because of its cost effectiveness, quick response with accuracy and
suitable for in-situ and on-site monitoring with good specificity and sensitivity. We utilized
graphene in the preparation of pristine graphene/polyaniline/hafnium oxide based
nanocomposites for electrochemical nonenzymatic dimethyl methylphosphonate (DMMP)
detection. Binary nanocomposites of PPG with varying ratios of pristine graphene and ternary
nanocomposite PPG/HfO2 were prepared for comparative study. We performed cyclic
voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies in order to
observe electrochemical response of nanocomposites modified glassy carbon electrode
(GCE) towards determination of DMMP. PPG3/HfO2/GCE exhibits highest current response
and lowest charge transfer resistance value of 3.92 KΩ ascribed to remarkable conductivity
of pristine graphene. The PPG3/HfO2/GCE demonstrated good selectivity for detection of
DMMP.
Accurate detection of ascorbic acid for food quality and healthcare is very important because
of its technological and health significance. Since ascorbic acid is a potent reducing agent and
an electroactive compound, its detection by applying electrochemical techniques have
received considerable attraction. In this work, a novel electrochemical sensing platform based
on reduced graphene oxide/polyaniline nanofibers/hafnium oxide nanoparticles
nanocomposites was designed for determination of ascorbic acid. The prepared
nanocomposites were characterized with FT-IR spectroscopy, X-ray diffraction, SEM and
EDX analysis. Cyclic voltammetric experiments indicated that PRGO1/HfO2/GCE
demonstrated good electrocatalytic activity towards ascorbic acid oxidation in neutral
solution. The effect of variable scan rate, pH and concentration with PRGO1/HfO2/GCE on
electrooxidation of ascorbic acid was also investigated.
