| China has a long history of planting potato,it is currently the country with the largest potato output in the world and has become the fourth largest staple food crop in China.With the increase of potato planting area,the loss of rural labor force and the promotion for agricultural production mechanization,the problem of weeds has become more and more prominent,which has seriously affected the yield and quality of potatoes,and has gradually become the main factors restricting potato production.Chemical weeding is convenient and quick,which not only guarantees the yield and quality of potatoes,but also improves economic efficiency.However,due to the long-term and large-scale use of herbicides and farmers’lack of scientific medication and environmental protection awareness,unscientific application and abuse of pesticides,problems such as phytotoxicity,weed resistance,excessive pesticide residues and environmental pollution continue to appear,which seriously damage the agricultural ecological environment,affect product quality and even cause human health.According to the actual needs of the application of mesotrione on potatoes,an improved Qu ECh ERS combined with HPLC-MS/MS technology was used to establish a method for the analysis of mesotrione residues in potatoes,The digestion dynamics of mesotrione in potato plants and soil were studied,the final residue of mesotrione in potato tubers and soil was determined,and the dietary risk of mesotrione on potato tubers was evaluated.The safe use of mesotrione on potatoes is proposed,and the test results are as follows:1.An analysis method for determination of mesotrione in potato plants,tubers and soil was established with an improved Qu Ch ECRS pretreatment method combined with HPLC-MS/MS technology.A mixture of acetonitrile and water（0.05%ammonium hydroxide）was employed to extract the mesotrione in potato plants,tubers and soil samples.Potato plants samples were purified by C18 and GCB,potato tubers and soil samples were purified by C18.Use acetonitrile and pure water（0.05%ammonia+5 mmol/L ammonium acetate）as mobile phase,mesotrione was detected with HPLC-MS/MS.The levels of addition of mesotrione in potato plants,potato tubers and soil were 0.01,0.05 and 0.5 mg/kg,the average recoveries of mesotrione in potato plants,potato tubers and soil were 76.3%～91.9%,83.6%～95.7%and 79.3%～94.4%,with the relative standard deviations of 3.6%～5.1%,2.1%～4.4%and 1.6%～7.7%.The method is simple,fast,reagent saving,accurate and reliable,and the recovery rate,sensitivity,accuracy,and precision meet the requirements of pesticide residue analysis.2.The degradation dynamics pattern of mesotrione in potato plants and soil have been examined.The degradation of mesotrione is consistent with first-order kinetics with a half-life between 0.5 and 1.1 d in potato plants and a half-life between 0.9 and 1.2 d in soil.Mesotrione are easily degradable pesticides because the half-life t1/2 of the mesotrione is less than 30 d.3.The residues of mesotrione in potato tubers and soil were measured.The results showed that the final residues of mesotrione in potato tubers and soil were all less than 0.01 mg/kg.At present,China has not formulated the maximum residue limit value of mesotrione on potato.The EU has established a maximum residue limit of mesotrione on potato of 0.01 mg/kg.Base on this,it is recommend that the maximum residue limit value of mesotrione on potato in China should be 0.01 mg/kg.4.Dietary risk assessment of mesotrione in potato tubers was conducted.According to the final residue test results and using the median final residual amount of mesotrione as the dietary risk assessment value.The results showed that the risk quotient was 1.57×10-5,which was much less than 1.Being evaluated the diet of mesotrione on potatoes risk,the daily intake of ordinary residents was 0.018 mg,and the risk of intake was 0.06%,which was less than 100%and shows that mesotrione is safe to be applied to potatoes. |
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