Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use...Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.展开更多
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 ...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.展开更多
Novel functionalized Arabic gums(AGs)were obtained by oxidation and acylation reactions on raw Arabic gum.The synthesized materials were used as modifiers of carbon paste electrodes for the determination of quercetin(...Novel functionalized Arabic gums(AGs)were obtained by oxidation and acylation reactions on raw Arabic gum.The synthesized materials were used as modifiers of carbon paste electrodes for the determination of quercetin(QCT),rutin(RUT)and both p-aminophenol(PAP)and acetaminophen(APAP)in 0.1 M phosphate buffer solution(PBS),pH 6.0.The identification of chemical functions on the surfaces of raw material was determined using Fourier transform infrared spectroscopy(FT-IR).Cyclic voltammetry and square wave voltammetry were used for the electrochemical study of QCT,RUT,PAP and APAP on modified electrodes.Electrochemical signals increased when the electrode was first modified with acylated gum in comparison to the unmodified electrode,and the signals became more important with the oxidized gum.Using oxidized AG modified carbon paste electrode(OAG-CPE),the linear range of the determination for both QCT and RUT was 0.020-0.090 mg/L,and from 1 to 9 mg/L for both PAP and APAP.Limits of detection were found to be 0.005,0.023,0.039 and 0.105 mg/L for QCT,RUT,PAP and APAP respectively.This sensor was first used for the direct quantification of APAP in commercialized tablets of DolipraneR 500 with a recovery of 94.3%,and secondly,for a simultaneous detection of both QCT and RUT in human urine.展开更多
文摘Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.
文摘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.
基金thank the International Science Program(ISP)for financial supportthank Dr.Tchieno MMF for recording FT-IR spectra.
文摘Novel functionalized Arabic gums(AGs)were obtained by oxidation and acylation reactions on raw Arabic gum.The synthesized materials were used as modifiers of carbon paste electrodes for the determination of quercetin(QCT),rutin(RUT)and both p-aminophenol(PAP)and acetaminophen(APAP)in 0.1 M phosphate buffer solution(PBS),pH 6.0.The identification of chemical functions on the surfaces of raw material was determined using Fourier transform infrared spectroscopy(FT-IR).Cyclic voltammetry and square wave voltammetry were used for the electrochemical study of QCT,RUT,PAP and APAP on modified electrodes.Electrochemical signals increased when the electrode was first modified with acylated gum in comparison to the unmodified electrode,and the signals became more important with the oxidized gum.Using oxidized AG modified carbon paste electrode(OAG-CPE),the linear range of the determination for both QCT and RUT was 0.020-0.090 mg/L,and from 1 to 9 mg/L for both PAP and APAP.Limits of detection were found to be 0.005,0.023,0.039 and 0.105 mg/L for QCT,RUT,PAP and APAP respectively.This sensor was first used for the direct quantification of APAP in commercialized tablets of DolipraneR 500 with a recovery of 94.3%,and secondly,for a simultaneous detection of both QCT and RUT in human urine.
