Abstract
A novel signal-amplified electrochemical assay for the determination of fenitrothion was developed, based on the redox behaviour of organophosphorus pesticides on a glassy carbon working electrode. The electrode was modified using graphene oxide dispersion. The electrochemical response of fenitrothion at the modified electrode was investigated using cyclic voltammetry, current-time curves, and square-wave voltammetry. Experimental parameters, namely the accumulation conditions, pH value, and volume of dispersed material, were optimised. Under the optimum conditions, a good linear relationship was obtained between the oxidation peak current and the fenitrothion concentration. The linear range was 1–400 ng·mL−1, with a detection limit of 0.1 ng·mL−1 (signal-to-nose ratio = 3). The high sensitivity of the sensor was demonstrated by determining fenitrothion in pakchoi samples.
Highlights
Electrochemical detection techniques, which are low cost, can be used for field measurements, and are generally not time consuming14, have been widely studied
The surface of the glassy carbon electrode (GCE) with dispersed graphene oxide is rough (Fig. 2B). These results confirm that the electrode surface was successfully modified by pipetting the graphene oxide dispersion onto the GCE
It shows that the only C presence on bare GCE and C, O presence on graphene oxide modified GCE, which confirmed that the loading of graphene oxide on GCE was successful
Summary
Electrochemical detection techniques, which are low cost, can be used for field measurements, and are generally not time consuming, have been widely studied. Wang et al. developed a glassy carbon electrode (GCE) coated with an acetylene black–chitosan composite film. They made an electrochemical sensor for detecting the irreversible reduction peak of methyl parathion, using a 30 s accumulation time under an open-circuit potential. After accumulation for 80 s, the oxidation peak of methyl parathion was scanned with the sensor; the linear range was 2.63–2632 ng·mL−1, and the detection limit was 2.34 ng·mL−1 (S/N = 3). A linear relationship between the stripping current and methyl parathion concentration was obtained in the concentration range 263.21–15 792.6 ng·mL−1, after adsorption for 2 min, and the detection limit was 13.16 ng·mL−1 after adsorption for 10 min. The results show that this is a reliable method for the determination of OPs, and has good potential for practical applications
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