高效液相色谱-串联质谱法检测稻田中吡嘧磺隆和苯噻酰草胺残留

采用高效液相色谱-串联质谱法(HPLC-MS/MS),建立了稻田水、土壤、水稻植株、稻秆、稻壳及糙米基质中吡嘧磺隆和苯噻酰草胺的残留分析方法。样品经20 m L V(乙腈)∶V(水)=70∶30的混合溶液提取,提取液用20 mg石墨化碳黑(GCB)与30 mg乙二氨基-N-丙基硅烷(PSA)净化,HPLC-M S/M S检测。吡嘧磺隆在上述各基质中的添加回收率在76%~107%之间,相对标准偏差(RSD)在1.5%~14%之间,定量限为0.004~0.01 mg/kg;苯噻酰草胺的添加回收率在77%~101%之间,RSD在2.4%~13%之间,定量限为0.001~0.01 mg/kg。实现了对两种除草剂同时简便、快速测定的要求。采用该方法测定了26%吡嘧磺隆·苯噻酰草胺水面扩展粒剂在稻田施用后,其有效成分吡嘧磺隆和苯噻酰草胺在实际样品中的残留量。结果表明,两种除草剂均属于易降解农药,在本试验条件下其在糙米中的残留量均低于我国最大残留限量(MRL)(吡嘧磺隆0.1 mg/kg;苯噻酰草胺0.05 mg/kg)。

Simultaneous determination of pyrazosulfuron-ethyl and mefenacet residues in rice by high performance liquid chromatography-tandem mass spectrometry

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for simultaneous determination of pyrazosulfuron-ethyl and mefenacet residues in rice. The samples were extracted with 20 mL V(acetonitrile):V(water)=70:30, then cleaned-up with 20 mg graphite carbon black (GCB) and 30 mg primary secondary amine (PSA). The average recoveries of pyrazosulfuron-ethyl spiked in paddy soil, paddy water, rice plant, rice straw, brown rice and rice husk ranged from 76% to 107% with the relative standard deviations (RSDs) of 1.5%-14%, and of mefenacet ranged from 77% to 101% with the RSDs of 2.4%-13%. The limit of quantifications(LOQs) were between 0.004 mg/kg and 0.01 mg/kg for pyrazosulfuron-ethyl and between 0.001 mg/kg and 0.01 mg/kg for mefenacet. The method was used for analyzing samples collected from the field trial of thepyrazosulfuron-ethyl and mefenacet mixture. And the results showed that the two herbicides were easily degradable and the terminal residues were below the maximum residue limit (MRL) established in China (0.1 mg/kg for pyrazosulfuron-ethyl; 0.05 mg/kg for mefenacet).