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Advisor(s)
Abstract(s)
A detailed study of voltammetric behavior of ethiofencarb (ETF) is reported
using glassy carbon electrode (GCE) and hanging mercury drop electrode (HMDE).
With GCE, it is possible to verify that the oxidative mechanism is irreversible, independent
of pH, and the maximum intensity current was observed at +1.20 V vs. AgCl/Ag
at pH 1.9. A linear calibration line was obtained from 1.0x10-4 to 8.0x10-4
mol L-1 with SWV method. To complete the electrochemical knowledge of ETF
pesticide, the reduction was also explored with HMDE. A well-defined peak was
observed at –1.00V vs. AgCl/Ag in a large range of pH with higher signal at pH
7.0. Linearity was obtained in 4.2x10-6 and 9.4x10-6 mol L-1 ETF concentration
range.
An immediate alkaline hydrolysis of ETF was executed, producing a phenolic
compound (2-ethylthiomethylphenol) (EMP), and the electrochemical activity of the
product was examined. It was deduced that it is oxidized on GCE at +0.75V vs.
AgCl/Ag with a maximum peak intensity current at pH 3.2, but the compound had
no reduction activity on HMDE.
Using the decrease of potential peak, a flow injection analysis (FIA) system
was developed connected to an amperometric detector, enabling the determination
of EMP over concentration range of 1.0x10-7 and 1.0x10-5 mol L-1 at a
sampling rate of 60 h-1. The results provided by FIA methodology were
performed by comparison with results from high-performance liquid chromatography
(HPLC) technique and demonstrated good agreement with relative deviations lower than 4%. Recovery trials were performed and the obtained values were between 98
and 104%.
Description
Keywords
Ethiofencarb Oxidation Reduction Square wave voltammetry Flow injection analysis Amperometric detection
Citation
Publisher
Taylor & Francis