灭蝇胺在茶树菇及其培养基质中的残留及消解动态

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，R2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/hm2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)。

Cyromazine residue and dissipation in Agrocybe aegerita and its substrates

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 R2 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 2 289 g a.i./hm2 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.