Study On Residue Detection And Degradation Of Five Pesticides In The Vegetables

Avermectin, emamectin benzoate, imidacloprid, indoxacarb, and zineb are the pesticides that used in vegetable greenhouse extensively. In this paper, for the study of the degradation of these five pesticides in the vegetables in solar greenhouse or open field, The main purpose of this study was to compare the differences in five pesticides degradationin solar greenhouse and open field, and the differences in five pesticides degradation in the spring and autumn season. The aim of this study was to find the environmental factors which cause the above major differences in the pesticides degradation. The results would provide a basis for scientific and rational use of pesticides, provide reference for improving the quality of vegetables, and ensuring food safety.Firstly, residues analysis methods of avermectin, emamectin benzoate, imidacloprid, indoxacarb and zineb in six vegetables were established using ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The results showed that the calibration curves were linear in the ranges of 50-2000 μg/L for zineb, and 5-200 μg/L for the rest of analytes.The correlation coefficients were in the range of 0.9951-0.9999. The spiked concentration ranges were 0.5-500 μg/kg for five compounds in the samples of bean, chilli, pakchoi, cucumber, asparagus and tomato, and the spiked recoveries were in the range of 70.8%-103.6% with relative standard deviations(RSD) of 4.5%-13.9%.The limits of detection for zineb ranged from 8.2 p.g/kg to 30μ/kg, and the limits of quantitation were in the range of 27-100μg/kg. The limits of detection for the rest of compounds were in the range of 0.02-0.7 μg/kg, and the limits of quantitation were 0.07-2.3 μg/kg.Digestion residue tests of pesticides in vegetables insolar greenhouse and open field showed that half-life of avermectin in bean, chilli, pakchoi, cucumber, asparagus and tomato in the solar greenhouse were 0.8-1.8 d, and half-life of avermectin of these vegetables in the open field were 0.7-1.5 d; The half-life of emamectin benzoate in bean, chilli, pakchoi, cucumber, asparagus and tomato in the solar greenhouse were 1.5-3.6 d, and were 1.1-2.2 d in the open field; The half-life of imidacloprid in beans, peppers, cabbage, cucumber, asparagus and tomato in solar greenhouse were 2.6-4.3 d, and were 2.3-3.5 d in the open field; The half-life of indoxacarb in bean, chilli, pakchoi, cucumber, asparagus and tomato in the solar greenhouse were 1.8-3.3 d, and were 1.4-2.5 d in the open field, The half-life of zineb in bean, chilli, pakchoi, cucumber, asparagus and tomato in the solar greenhouse were 1.3-2.0 d, and were 1.1-2.2 d in the open field. The digestion rates of five kinds of pesticides in bean, chilli, pakchoi, cucumber, asparagus and tomato in the open field were faster than these in the solar greenhouse. During the test, there were no wind and rain.Digestion residue tests of five kinds of pesticides in six kinds of vegetables were also conductded in the open field in autumn, and were compared with the digestion residue tests of those pesticides in spring. Results showed that digestion rates of these five kinds of pesticides in abamectin, emamectin benzoate, imidacloprid, indoxacarb and zineb in autumn were higher than that in spring, and high temperature could promote the degradation of five pesticides.Based on the digestion residues of five pesticides in vegetables in the greenhouse and open field trials, as well as seasonal factors test, it initially showed that light intensity, and temperature were the main environmental factors for the residual digestion of pesticides.