苹果和土壤中甲基硫菌灵及其代谢物残留消解动态

Dynamics and Residue of Thiophanate-Methyl and Its Metabolite in Apple and Soil

研究了甲基硫菌灵及其代谢物多菌灵在苹果和土壤中的消解动态和最终残留.苹果和土壤中甲基硫菌灵及多菌灵采用乙酸乙酯提取,提取液经旋转蒸发仪浓缩后经SPE 氨基净化柱净化,过0.22 μm 滤膜后上机,采用超高效液相色谱和272 nm紫外检测器检测,外标法定量.添加浓度为0.05、1.0、5.0 mg·kg^-1 时,苹果中甲基硫菌灵的添加回收率在76.3%-108.5%之间,相对标准偏差为1.7%-5.7%;土壤中甲基硫菌灵的添加回收率在90.0%-106.7%之间,相对标准偏差为2.6%-7.4%;苹果中多菌灵的添加回收率在82.7%-109.3%之间,相对标准偏差为8.6%-11.5%;土壤中多菌灵的添加回收率在77.9%-116.9%之间,相对标准偏差为4.8%-7.3%;检测方法满足农药留分析要求.在山东省泰安市、安徽省宿州市、河北省保定市3 个试验点两年的消解动态试验结果表明：施药后,甲基硫菌灵在苹果和土壤中均很快转化为多菌灵.甲基硫菌灵在苹果和土壤中的半衰期均小于6.3 d,属于易降解农药.两年三地的最终残留试验结果表明,甲基硫菌灵及代谢物多菌灵在苹果和土壤中最终残留量均低于0.05 mg·kg^-1,小于我国规定的最大残留限量（MRL）3.0 mg·kg^-1 和欧盟规定的MRL 0.5 mg·kg^-1.说明按照推荐的甲基硫菌灵在苹果上的施用方法：施用药量（有效成分）500 mg·kg^-1,施药2 次,施药间隔7 d,采收间隔期大于21 d,在以上条件下施药是安全的.

To supervise and ensure apple’s quality and safety, residues dynamics and final residual levels of thiophanate-methyl and carbendazim in apple and soil were investigated in three different regions of China (Shandong, Anhui and Hebei). A method was illustrated to detect thiophanate-methyl and carbendazim residues in apple and soil. The residues in the samples were extracted with ethyl acetate, cleaned up with amino solid phase extraction column and 0.22μm filter membrane, and then analyzed by UPLC with an ultraviolet detector at 272 nm. The analytes were by matrix matched standard solution. When spiked 0.05, 1.0, 5.0 mg·kg-1, the recoveries of thiophanate-methyl in apple and soil were 76.3%~108.5% (RSD 1.7%~5.7%) and 90.0%~106.7% (RSD 2.6%~7.4%), while which of carbendazim were 82.7%~109.3% (RSD 8.6%~11.5%) and 77.9%~116.9% (RSD 4.8%~7.3%), respectively, which indicated this method match the requirement of the detection. The trial results showed that thiophanate-methyl was degraded to carbendazim in apple and soil rapidly due to all half-lives were below 6.3 d, and the final residual levels of thiophanate-methyl and carbendazim in apple and soil were far below the MRLs of China (3.0 mg·kg-1) and European (0.5 mg·kg-1) due to the maximum residual was under 0.05 mg·kg-1. Therefore, the apples with thiophanate-methyl applied, according to the recommend method, 500 mg·kg-1 effective ingredient application twice, with 7 days application interval and 21 days collection interval, is safe.