灭蝇胺在茶树菇及其培养基质中的残留及消解动态

Cyromazine residue and dissipation in Agrocybe aegerita and its substrates

为检测灭蝇胺在茶树菇及培养基质(菌棒)上、中、下3部分的残留量及消解动态,以50%灭蝇胺可溶性粉剂为供试药剂,对灭蝇胺在茶树菇及其菌棒中的最终残留及消解动态进行研究。样品经甲醇提取,加入氯化钠后高速离心净化,采用液相色谱-串联质谱法测定,外标法定量。结果表明:在0.002~0.05 mg/L和0.01~0.2 mg/L线性范围内,灭蝇胺的质量浓度与其峰面积间线性关系良好,R^(2)分别为0.997和0.998。在0.01、0.1和1 mg/kg 3个添加水平下,灭蝇胺在茶树菇和菌棒中的平均回收率为72%~110%,相对标准偏差为2%~6%。灭蝇胺在茶树菇上的降解符合一级反应动力学模型,半衰期为5.46 d;其在菌棒中残留主要集中在上段,占菌棒总残留量的65.8%~93.2%。50%灭蝇胺可溶性粉剂按有效成分2289~3433.5 g/hm^(2)的剂量,在茶树菇上采用手动喷雾施药3~4次,距最后一次施药后3 d时,灭蝇胺在茶树菇中的残留量在0.10~0.17 mg/kg之间,低于美国规定的灭蝇胺在食用菌上的最大残留限量(1.0 mg/kg)。

In order to measure the dissipation and residues of cyromazine in Agrocybe aegerita and its substrates,50%cyromazine SP was used as the test agent.The pesticide distribution in Agrocybe aegerita and the dissipation dynamics in its substrates were investigated.The samples were extracted by methanol,purified by high-speed centrifugation after the addition of sodium chloride,determined by LC-MS/MS and quantified by external standard method.The results showed that there was a good linear relationship between the mass concentration and the peak area in the range of 0.002-0.05 mg/L and 0.01-0.2 mg/L,and R^(2)were 0.997 and 0.998,respectively.When the spiked levels were 0.01,0.1 and 1 mg/kg in the mushroom and its substrates,the average recoveries ranged from 72%to 110%,with RSDs(n=5)ranged from 2%-6%,which met the inspection requirement of pesticide residue analysis methods.The dissipation of cyromazine in Agrocybe aegerita was in accordance with the first-order kinetic model,and the half-life was 5.46 d.The main residues of cyromazine in substrates were in the upper part,accounting for 65.8%-93.2%of the total residues.The residues of cyromazine in the mushroom were lower than the MRL in the US(1.0 mg/kg)3 days after treated by the dosages of 2289 g a.i./hm^(2)and 1.5 times of that,by manual spraying for 3-4 times,which were between 0.10 mg/kg and 0.17 mg/kg.