| In this article, a gas chromatography-mass spectrametric (GC-MS) method was established to detect the residues of carbosulfan and its metabolites(including carbofuran and 3-hydroxycarbofuran) in cowpea and soil, and used the method to study the residual dynamics of carbofuran and 3-hydroxycarbofuran in cowpea and soil, which aims at finding the residues regularity and correlation in cowpea and soil as well as finding the major reason why banned pesticides (including carbofuran and 3-hydroxycarbofuran) are still detected, then a scientific and effective prevention measures was put forward to reduce safe risk of banned pesticides carbofuran and 3-hydroxycarbofuran. At the same time, studying on the removal efficiency of different processing method for pesticides including Acetamiprid, Carbendazim, Cyromazine, Thiamethoxam, which are detected frequently in cowea, in order to ensure the safe edible of cowpea, provide scientific basis to guarantee the safety of pesticide residues in cowpea. The main contents and results of this research showed as follows:A rapid gas chromatography-mass spectrametric (GC-MS) detection and analysis method were established to detect carbosulfan, carbofuran and 3-hydroxycarbofuran in cowpea and soil. The sample was extracted with acetonitrile-acetone(7:3,V/V) and acetone-petroleum ether(6:4,V/V) by shaking table, then through extraction purified by Florisil column and anhydrous sodium sulfate and high speed centrifugation, in the end detected by gas chromatography-mass spectrametric (GC-MS). The results showed that the linear relationship is good when the addition of carbosulfan, carbofuran and 3-hydroxycarbofuran changed from 0.05mg/L to 5.00mg/L. The minimum detectable concentration was 0.005mg/kg,0.0003mg/kg, 0.001mg/kg respectively. When the added concentration of sample under 0.05mg/kg,0.5mg/kg,2mg/kg three addition level, the average recoveries of carbosulfan, carbofuran and 3-hydroxycarbofuran ranged from 71.3%～85.42%,80.15%～104.35%,81.25%～99.31% respectively, and its relative standard deviation was 3.55%～3.8%,5.1%～6.03%,6.66%～8.6%. The method has some advantages such as high sensitivity, simple operation, short time of treatment, low cost for detection compare with the other method that mention in other literature, the method is suitable for the detection of mass sample in the laboratory.Study on the degradation of carbofuran and 3-hydroxycarbofuran in cowpea and soil after spraying respectively six kinds of different concentrations carbosulfan and carbofuran,. The results showed that the half-life of carbofuran was 0.9 to 1.3 days in cowpea, the residues of carbofuran in soil show a tendency that increased initially and then decreased, the highest residues of carbofuran appears in three or five days after spraying, after twenty-one days, the residues of carbofuran has almost no residue; after spraying carbosulfan, the residues of 3-hydroxycarbofuran in cowpea show a tendency that increased initially and then decreased, the highest residues of 3-hydroxycarbofuran appears in three or five days after spraying, after fourteen days, the residues of 3-hydroxycarbofuran has almost no residue. in soil, after five days only to find the residue of 3-hydroxycarbofuran, seven days later, the residues of 3-hydroxycarbofuran has almost no residue; after spraying carbofuran, the half-life of carbofuran was 0.7 to 3.3 days in cowpea, the half-life of carbofuran was 0.8 to 1.4 days in soil; after spraying carbofuran, the residues of 3-hydroxycarbofuran in cowpea show a tendency that increased initially and then decreased, the highest residues of carbofuran appears in one day after spraying, seven days later, the residues of 3-hydroxycarbofuran has almost no residue. in soil, after five days only to find the residue of 3-hydroxycarbofuran, twenty-one days later, the residues of carbofuran has almost no residue.The residues correlation of carbofuran and 3-hydroxycarbofuran in cowpea and soil was analysised in the article. after spraying carbosulfan in two hours, one day, three days, five days, seven days, the correlation coefficient of carbofuran in cowpea and soil is 0.94,0.96,0.97,0.85,0.95 respectively, the correlation coefficient are all over 0.8; after spraying carbofuran two hours, one day, three days, five days, the correlation coefficient of carbofuran in cowpea and soil are 0.85,0.83,0.83,0.89 respectively, the correlation coefficient are all over 0.8; after spraying carbosulfan in five days, the correlation coefficient of 3-hydroxycarbofuran in cowpea and soil is 0.87, the correlation coefficient is over 0.8; after spraying carbofuran in five days, the correlation coefficient of 3-hydroxycarbofuran in cowpea and soil are 0.92 respectively, the correlation coefficient are all over 0.8; so at different time, after spraying carbosulfan and carbofuran, the residues of carbofuran and 3-hydroxycarbofuran in cowpea and soil showed positive correlation highly.In this paper, the effect of tap water tap rinsing and the effect of immersion time in 50 ℃ water,2% salt water,2% detergent,2% vinegar and 2% NaHCO3 on acetamiprid,carbendazim,cyromazine,thiamethoxam,which are high frequency detection in cowpea were analyzed through liquid chromatography tandem mass spectrometry detection. the results showed that:Using the methods, the removal rate of acetamiprid was between 13.61%～49.17%%, the removal rate of carbendazim was between 19.77%～ 51.52%, the removal rate of cyromazine was between 13.68%-51.15%, the removal rate of thiamethoxam was between 15%～52.65%.the results showed that:after treatment, four kinds of pesticides have different degree of degradation, which can effectively reduce the pesticide safety risk.immersing in 2%NaHCO3 for 30 minutes is the best method which removal rate reach 49.17%～52.65%. |
