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    QuEChERS-超高效液相色谱-串联质谱法测定大米和小麦中7种吡啶类农药的残留量

    Determination of Residues of 7 Pyridine Pesticides in Rice and Wheat by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry with QuEChERS

    • 摘要: 考虑到标准方法GB 23200.50—2016测定时前处理过程较为复杂,采用题示方法测定大米和小麦中氟硫草定、吡虫啉、氟啶草酮、噻唑烟酸、咪唑乙烟酸、啶虫脒和啶酰菌胺等7种吡啶类农药的残留量。取适量大米或小麦样品,粉碎,过筛后分取2.00 g,加入5 mL水,涡旋混匀,静置30 min。加入10 mL乙腈和2 g氯化钠,涡旋5 min,离心5 min。收集上清液,转移至盛有300 mg C18和2.0 g无水硫酸钠的15 mL离心管中,涡旋1 min,离心5 min,过0.22 μm亲水聚四氟乙烯针式过滤器,滤液采用超高效液相色谱-串联质谱法测定。在色谱分析中,以Shimadzu shim-pack GIST C18色谱柱作固定相,不同体积比的乙腈和0.05%(体积分数)甲酸溶液的混合溶液作流动相进行梯度洗脱;在质谱分析中,以电喷雾离子源正离子(ESI+)模式电离,多反应监测(MRM)模式检测,基质匹配法定量。结果显示:啶酰菌胺的质量浓度在2.0~50.0 μg·L−1,其他6种农药的质量浓度在1.0~50.0 μg·L−1内和对应的峰面积呈线性关系,测定下限(10S/N)为0.010 mg·kg−1(啶酰菌胺)和0.005 mg·kg−1(其他6种农药)。在0.01,0.05,0.2 mg·kg−1加标浓度水平下,7种吡啶类农药的回收率为74.6%~103%,测定值的相对标准偏差(n=6)为0.84%~6.9%,和GB 23200.50—2016的回收率为72.1%~99.7%,测定值的相对标准偏差(n=6)为1.1%~6.8%基本一致,说明将GB 23200.50—2016中的固相萃取法转换为QuEChERS是可行的,且QuEChERS前处理过程简单、快速,更适合批量样品的检测。

       

      Abstract: Considering the complexity of the pre-processing process for standard methods of GB 23200.50—2016, the title method was used to determine the residue of 7 pyridine pesticides, including dithiopyr, imidacloprid, fluridone, thiazopyr, imazethapyr, acetamiprid and boscalid, in rice and wheat. An appropriate amount of rice or wheat samples was taken, crushed, and sieved. An aliquot (2.00 g) was taken, and 5 mL of water was added. The mixture was mixed well by vortex and settled for 30 min, and 10 mL of acetonitrile and 2 g of sodium chloride were added. The mixture was vortexed for 5 min, and centrifuged for 5 min. The supernatant was collected, and transferred to a 15 mL-centrifuge tube containing 300 mg of C18 and 2.0 g of anhydrous sodium sulfate. The mixture was vortexed for 1 min, centrifuged for 5 min, and passed through a 0.22 μm hydrophilic PTFE syringe filter. The filtrate was determined by ultra-high performance liquid chromatography-tandem mass spectrometry. In chromatographic analysis, Shimadzu shim-pack GIST C18 chromatographic column was used as the stationary phase, and a mixture of acetonitrile and 0.05% (volume fraction) formic acid solution at different volume ratios was used as the mobile phase for gradient elution. In the mass spectrometry analysis, the ESI+ mode was used for ionization, the MRM mode was used for detection, and the matrix matching method was used for quantification. It was shown that linear relationships between values of the mass concentration and corresponding peak area were kept in the ranges of 2.0-50.0 μg·L−1 for boscalid and 1.0-50.0 μg·L−1 for the other 6 pesticides, with lower limits of determination (10S/N) of 0.010 mg·kg−1 for boscalid and 0.005 mg·kg−1 for the other 6 pesticides. At the spiked concentration levels of 0.01, 0.05, 0.2 mg·kg−1, the recoveries of 7 pyridine pesticides were found in the range of 74.6%-103%, and RSDs (n=6) of the determined values ranged from 0.84% to 6.9%, which were basically consistent with those (the recoveries were 72.1%-99.7%, and RSDs (n=6) of the determined values were 1.1%-6.8%) given from GB 23200.50—2016, indicating that converting the solid phase extraction method in GB 23200.50—2016 to QuEChERS was feasible, and the pre-processing process of QuEChERS was simple, fast, and more suitable for detection of batch samples.

       

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