同位素内标法检测灭蝇胺及其代谢物三聚氰胺在双孢蘑菇子实体和覆土中的残留

采用超高效液相色谱-串联质谱内标法检测灭蝇胺及其代谢物三聚氰胺在双孢蘑菇 Agaricus bisporus 子实体和覆土中的残留量，以及两者在双孢蘑菇工厂化栽培中的变化规律。样品经 V (甲醇) : V (水) = 4:1混合溶液提取，MCX固相萃取柱净化，HILIC 色谱柱分离，超高效液相色谱-串联质谱测定，三聚氰胺-13C同位素内标法定量。结果表明:灭蝇胺和三聚氰胺的检出限均为0.001 mg/kg。在0.02~1 mg/kg添加水平下，灭蝇胺在双孢蘑菇子实体和覆土样品中的回收率为86%~102%，相对标准偏差 (RSD) 为2.7%~5.3%；三聚氰胺在子实体和覆土样品中的回收率为98%~103%，RSD为1.5%~2.4%。在有效成分为1、10、50和250 mg/kg施药水平下，灭蝇胺消解规律符合一级反应动力学，在覆土中的平均半衰期为31.3 d。在覆土中灭蝇胺会转化为三聚氰胺，第2潮蘑菇采摘结束后，覆土中灭蝇胺的转化率为8.58%~13.87%。在施药水平较高 (50、250 mg/kg) 时，灭蝇胺和三聚氰胺在第1潮菇中的残留量高于在第2潮菇中的，其最高检出量灭蝇胺为2.36 mg/kg，三聚氰胺为1.75 mg/kg。综合考虑环境和产品安全，建议灭蝇胺的使用量不宜超过50 mg/kg。

Determination of cyromazine and melamine residues in fruiting body and casing soil of Agaricus bisporus by isotope-labeled internal standard method

Residual concentrations of cyromazine and its degradation metabolite melamine in fruiting body and casing soil of Agaricus bisporus were monitored by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and isotope-labeled internal standard method. Samples were extracted with methanol-water (4:1, V/V), purified by a strong cation exchange-solid phase column (MCX-SPE), and separated through a HILIC column. The samples were then monitored by UPLC-MS/MS using 13C-melamine as the isotopic internal standard. The results showed that the limit of detection (LOD) of cyromazine and melamine were both 0.001 mg/kg. Within spiked concentrations between 0.02-1.0 mg/kg, the recovery rates of cyromazine and melamine in both casing soil and fruiting body were 86%-102% (RSD ≤ 5.3%) and 98%-103% (RSD ≤ 2.4%), respectively. With spiked concentrations of 1, 10, 50, and 250 mg/kg, the dissipation of cyromazine in casing soil followed the first-order kinetics with an average half-life of 31.3 d. The cyromazine was degraded into melamine by the end of the second flush mushroom dspicked, with the conversion percent of 8.58%-13.87%. After the application of cyromazine with high concentrations (50 and 250 mg/kg), the residue of cyromazine and melaminein is higher in the first flush mushrooms than that in the second flush mushrooms. And the highest detected concentrations of cyromazine and melamine were 2.36 mg/kg and 1.75 mg/kg, respectively. To meet the requirement of environmental and food safety, the application amount of cyromazine was recommended to be no more than 50 mg/kg.