阴极溶出伏安法测定某些二硫代磷酸酯类农药的研究

本文提出了一种测定痕量有机磷农药的新方法——阴极溶出伏安法测定某些二硫代磷酸酯类农药。大部分二硫代有机磷农药在碱性溶液中都水解生成二硫代磷酸酯,而这个化合物在静止汞电极上具有很高的灵敏度。作者合成了二硫代磷酸0,0-二乙酯纯品,研究了它的溶出伏安法性质和测试条件。此化合物于碱性底液中,在电位-0.9V附近出现尖锐的溶出峰,溶出峰高度与浓度在10~(-6)—10~(-9)M范围内具有线性关系。作者应用上述原理测定了数种二硫代有机磷农药,并成功地检测了茶叶表面残留的微量农药。本文还通过对比实验,证明了二硫代磷酸酯分子中的巯基是使其具有电化学活性的真正原因。从而给采用溶出伏安法测定其他含巯基农药提供了理论依据。

A STUDY OF CATHODIC STRIPPING VOLTAMMETRY FOR DETERMINATION OF SOME DITHIODIAiLKYLPHOSPHORIC ACID PESTICIDES

This paper reports a new method for determination of trace amounts of some dithiodialkylphosphoric acid pesticides. In alkaline solution, most of those pesticides are hydrolyzed into dithiodialkylphosphate which has high sensitivity at the stationary mercury electrode. Authors have synthesized 0, 0-diethyldit-hiophosphate and studied the analytical conditions in stripping voltammetry. This compound shows a sharp stripping peak at about -0.9V (vs. Ag-AgCl) in a NaOH-NaHCO₃ buffer solution and a linear relationship exsists between the peak height and the concentration in the range of 10^-6-10^-9M. Several organophosphorus pesticides with dithio groups and their residues in trace amounts on the surface of tea leaves have been determined successfully by the proposed method. It has also been demonstrated by control experiment that the thiohydroxy group in dithiophosphate plays its important role of possessing electrochemical activity. Hence a theoretical ground is provided for further determination of other pesticides containing thiohydroxy group by cathodic stripping voltammetry.