Abstract
3-methyl-4-nitrophenol (MNP) is the main by-product of the organophosphate insecticide fenitrothion (FT), used in locust control. MNP is highly toxic because it is an endocrine disruptor and then may cause adverse in the biological systems. Then, it is necessary to develop analytical methods for determination of this pollutant in the environment. In this sense, we reported herein the development of an electrochemical sensor for the detection of 3-methyl-4-nitrophenol (MNP), one of the metabolites of fenitrothion (FT), by using naked and modified carbon fiber microelectrode (CFME) by nickel tetrasulfonated phthalocyanine polymer (CFME/p-NiTSPc). The voltammogram showed that MNP presents one irreversible anodic peak corresponding to the oxidation of the phenol group at 0.9 V vs Ag/AgCl. The effect of pH of the buffer on the peak current and SWV parameters such as frequency, scan increment and pulse amplitude were investigated in order to optimize the electrochemical response of the sensor. The obtained results lead to the following optimum value: pH = 6; frequency = 25 Hz, pulse amplitude = 50 mV, scan increment = 10 mV. With these optimum values, the calibration curves show that the peak current varied linearly upon MNP concentration leading to a limit of detection (LoD) for naked CFME close to 3 μg/L whereas for CFME modified by p-NiTSPc, it reaches 0.75 μg/L. This results prove that the presence of p-NiTSPc increasing the sensitivity of the sensor could be used to monitor 3-methyl-4-nitrophenol residue in real matrix.
Highlights
The relentless pursue of improving productivity and agricultural products quality has led man to a massive use of pesticides
The calibration curves show that the peak current varied linearly upon MNP concentration leading to a limit of detection (LoD) for naked carbon fiber microelectrode (CFME) close to 3 μg/L whereas for CFME modified by p-NiTSPc, it reaches 0.75 μg/L
We report the use of CFME modified by nickel tetrasulfonated phthalocyanine polymer (p-NiTSPc) film for methylparathion and its metabolite p-nitrophenol in water [7]
Summary
The relentless pursue of improving productivity and agricultural products quality has led man to a massive use of pesticides. Fenitrothion, an organophosphate insecticide is widely used in cotton cultivation in the north of Burkina Faso in the fight against locust attack It is well-known that it possesses some toxicity because it acts as acetylcholinesterase inhibitors and its residues and metabolites are present in food chain and environment [2] [3] [4] [5]. The commonly used analytical methods are the high-performance liquid chromatography (HPLC), mass spectrometry (MS), gas chromatography (GC) or coupled techniques GC-MS and ELISA [3] [4] [6] [7] These techniques require means huge, skilled technicians, very long analysis time, a step of sample pretreatment and they are not suitable for analysis of organophosphate pesticides due to their instability. We report the electrochemical modification of CFME by p-NiTSPc for the detection 3-methyl-para-nitrophenol (MNP), one of the stable by-product of fenitrothion in water
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