Studies On Methods Of Rapid Detection Of Organophosphorus And Carbamate Pesticides By Potentiometry

Abstract: Organophosphorus and N-methylcarbamate pesticides are widely used in agriculture product for its high insecticidal activity. They are often regarded as important hazard substance in food safety inspection due to its high acute toxicity to human and animals. Some virulent kinds of organophosphorus and carbamate pesticides are still used to vegetables and fruits in some regions although it forbidden by the government, the toxicosis incidents of human and animal resulted from taking food which contains high level of pesticide residues are happened usually. The excessive pesticide residues not only harm the people health but also impact the credit and benefit of agriculture products in international trade, and therefore leading our agriculture products can't exert its advantage in international market competition.At present, GC is common method for detecting organophosphorus and N-methylcarbamate pesticides residues, which has high veracity and sensitivity, but it's too expensive and complex to use as a method for fieldwork detection. There are many researches on the methods of rapid detection as well, especially the enzyme inhibition method. Potentiometry is one of the enzyme inhibition methods, but it has few researchs on its stability, sensitivity, practicability and the limit of detection. The aim of this study is to search a convenient, rapid, sensitive, credible and practical method to be used for pesticide residues detection in fruits and vegetables at markets. The results are as follow:1. The reaction system of potentiometry method has been established. The plant esterase we used was prepared by our laboratory. The reaction system is as follows: 1.8mL diluted enzyme solution, 0.5mL of 0.5% a-Naphthyl acetate, and 4.6mL water. React at 40°C for 30min, and then put them into boil water for 2min. Measuring the ApH values after the reaction, make standard work curve with the pesticide concentration vs the enzyme inhibition ratio, the result will calculate by the inhibition ratio of the sample.2. 29 kind organopuosphorus and N-methylcarbamate pesticides has been detected by this method for water sample, the sensitivity of organopuosphorus pesticides was between 0.000625mg/kg and 0.0625mg/kg and of N-methylcarbamate pesticides was...