水样中甲基对硫磷的线性扫描伏安测定法

Determination of Methyl Parathion in Water Samples by Linear Sweep Voltammetry

目的建立了水样中甲基对硫磷的线性扫描伏安测定法。方法采用三电极系统,以电化学活化玻碳电极为工作电极,Ag-AgCl电极为参比电极,铂电极为对电极,在HAc-NaAc缓冲溶液(pH=5.0)中,采用循环伏安法在-0.8～0.5 V扫描电位、0.1 V/s扫描速度下,研究14.4μmol/L的甲基对硫磷的电化学行为。结果活化玻碳电极对甲基对硫磷具有明显的电催化作用,电极反应过程是吸附控制过程。催化氧化峰电流与甲基对硫磷浓度在0.72～14.4μmol/L范围内呈良好的线性关系,线性方程为ipa=0.105 3+0.246 0c,r=0.999 2,该方法的检出限为0.425μmol/L,平均回收率为98.0%～101.9%,RSD为2.7%。结论该方法简便、快捷、灵敏度高,适用于实际水样中甲基对硫磷的测定。

Objective To establish a method for electrochemical determination of trace methyl parathion in water samples with electrochemical activated glassy carbon electrode （EGCE）. Methods A three-electrode configuration was employed,the working electrode was EGCE, the reference and counter electrode were Ag-AgCl electrode and platinum electrode. In the HAc- NaAc buffer solution （pH=5.0） ,the electrochemical behavior of methyl parathion was studied within the concentration scope of 14.4 μmol/L for linear sweep voltammetry with -0.8-0.5 V and scan rates 0.1 V/s. Results The electro-activated glassy carbon electrode had obvious catalytic effects on methyl parathion and the electrochemical behavior of methyl parathion was a surface-controlled process. There was a good linear relationship with a linear equation of ipa=0.105 3＋0.246 0c and a correlation coefficient of 0.999 2 between the oxidation peak current and the methyl parathion within the concentration scope of 0.72-14.4 μ mol/L and the low detection limit was 0.425 μmol/L. The recovery rates were in the range of 98.0%-101.9% ,and the relative standard deviation was 2.7%. Conclusion This method is simple ,fast,sensitive and applicable to the determination of methyl parathion in practical water samples.