Study On The Rapid Determination Of Pesticide Residues In Fruits And Vegetables

This paper is the subitem of key project of food safety of the Science and Technology Ministry of China. In order to solve the problems of rapid determination system for pesticide residues in fruits and vegetables, two issues were studied. Opitimization on commercial reagent of acetylcholinesterase (AChE) reaction system was studied for saving the cost of reagent. Subcritical water extraction was used to extract pesticide residues, and compared with other pretreatment methods. The research aspects are as follows: 1. AChE reaction system is a reliable method to detect pesticide residues in fruits and vegetables except whose detecting cost of reagent is higher. In promise of higher sensitivity, a new low cost reagent components, whose dosage of enzyme, substrate and chromogenic reagent are 3/4, 3/4 and 1/2 that of original components, respectively, thus saved of 1/3 cost of reagent as a whole, was achieved through contrastive test. F-test proved that there is no significant difference between adjusted components and original components. The lower limit of determination of adjusted components to three pesticides is: methamidophos 0.3mg/L, trichlorphon 0.04mg/L, dichlorvos 0.02mg/L, which is consistent with those of national standard rapid determination method. 2. A GC-ECD analytical method was build to detect trichlorphon residues, whose linear coefficients of standard curve is 0.998 and detecting range is 10~200μg/L. 3. A comparison of manual shaking extraction, ultrasonic extraction, subcritical water extraction and microwave assistanted extraction to simulated vegetable samples was studied. Analytical results of GC indicated that, to trichlorphon residues in Chinese Cabbage, the extraction rate of subcritical water extraction and microwave assistanted extraction is higher than that of manual shaking extraction and ultrasonic extraction. 4. A rapid pretreatment technology, subcritical water extraction technology, was researched by AChE analytical method. The optimal methamidophos extraction condition i.e. temperature 100 ~ 120°C, extraction time 2 ~ 4min was achieved by simulated sample test. Compared with shaking extraction and ultrasonic extraction, subcritical water extraction can get higher extraction rate, better precision and simpler operation. We also designed subcritical water extraction device primarily. The fruits has been used to 'Multichanel Food Safety Detection Instrument', which is also researched by ourselves, and is authenticated international good performance by Science and Technology Bureau of Hubei Province.