衍生伏安法测定蔬菜中的敌百虫

Determination of Trichlorfon in Vegetables by Derivatization Voltammetry

敌百虫在碱性溶液中水解为敌敌畏,其进一步水解转化成磷酸二甲酯和二氯乙醛,在酸性条件下,盐酸苯肼与二氯乙醛发生反应,生成苯肼-二氯乙醛腙,其还原电位在-784mV(vs.SCE)的二阶导数伏安还原波的灵敏度,比优化条件下敌百虫的灵敏度提高了200倍。基于此,拟定了测定蔬菜中敌百虫的新方法。本法测定的敌百虫含量在1.6～83μg/L范围内与苯肼-二氯乙醛腙呈良好的线性关系,线性相关系数r=0.9912。检出限可达0.55μg/L,本方法测定速度快、灵敏度高、样品处理简单,用于蔬菜中敌百虫含量的测定,结果满意。

A derivatization polarographic method was developed for the determination of trichlorfon in vegetables. The trichlorfon was hydrolyzed into dimethyl phosphate and dichloroacetaldehyde, and then the hydrazone was fi）rmed from the reaction of diehloroaeetaldehyde with phenylhydrazine. A sensitive second derivation vohammetry wave of the hydrazone was obtained at -784 mV（vs. SCE）by single sweep oscilloplolarography. The sensitivity to hydrazone is 200 times larger than that to trichlorfom in optimum conditions. The peak current is proportional to the concentration of trichlorfon over the range of 1.6 -83 ug/L （r =0. 9912）, and the limit of detection is 0.55 ug/L. This method has been used for the determination of triehlorfon in vegetables due to its simpletiy, reliableieity and rapidity.