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    磁性石墨烯固相萃取-超高效液相色谱-串联质谱法测定果蔬汁中36种农药的残留量

    Determination of Residues of 36 Pesticides in Fruit and Vegetable Juice by Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry with Magnetic Graphene Solid Phase Extraction

    • 摘要: 取果蔬汁样品2.00 g置于50 mL离心管中,加入20 mL乙腈,涡旋2 min,离心5 min,残渣用20 mL乙腈重复提取一次,合并上清液,旋转蒸干,加入10 mL 10%(体积分数,下同)乙腈溶液溶解,加入40.0 mg磁性石墨烯(化学共沉淀法制备),涡旋20 min,沉淀物由磁铁收集,弃去上清液,加入1.0 mL丙酮,涡旋1 min,重复洗脱操作2次,合并上清液,用氮气吹干,用1 mL 10%乙腈溶液溶解并定容,采用超高效液相色谱-串联色谱法(UHPLC-MS/MS)测定36种农药的残留量。以Agilent Eclipse Plus C18色谱柱为固定相,以不同体积比的0.1%(体积分数)甲酸溶液-乙腈混合液为流动相进行梯度洗脱,采用电喷雾离子(ESI)源,在正离子(ESI+)模式下进行多反应监测(MRM)模式质谱分析。结果表明,36种农药的质量浓度在一定范围内与对应的定量离子的峰面积呈线性关系,检出限(3S/N)为0.001~0.006 mg·kg-1。按照标准加入法进行回收试验,回收率为61.3%~104%,测定值的相对标准偏差(n=6)均小于12%。方法用于测定20份实际果蔬汁样品中36种农药的残留量,其中部分样品检出克百威、吡虫啉、多菌灵、氧乐果、腈菌唑,检出量为0.010~0.034 mg·kg-1

       

      Abstract: 2.00 g of the fruit and vegetable juice sample was taken and placed in a 50 mL-centrifuge tube. 20 mL of acetonitrile was added, and the mixture was vortexed for 2 min and centrifuged for 5 min. The extraction of the residue was repeated with 20 mL of acetonitrile, and the supernatants were combined. The mixture was rotary evaporated to dryness, and 10 mL of 10% (volume fraction, the same below) acetonitrile solution was added to dissolve. 40.0 mg of magnetic graphene (prepared by chemical co-precipitation method) was added, and the mixture was vortexed for 20 min. The sediment was collected by a magnet, and the supernatant was discarded. 1.0 mL of acetone was added and the solution was vortexed for 1 min. The elution was repeated twice. All supernatants were combined and blown to drynesss by nitrogen, and made its volume up to 1 mL with 10% acetonitrile solution. The residues of 36 pesticides were determined by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Agilent Eclipse Plus C18 column was used as the stationary phase and the mixed solution composed of 0.1% (volume fraction) formic acid solution and acetonitrile at different volume ratios was used as the mobile phase for gradient elution.Electrospray ion (ESI) source was used for mass spectrometry. The targets were analyzed by multiple reaction monitoring (MRM) mode in positive ion (ESI+) scanning mode. As shown by the results, linear relationships between the corresponding quantitative ion response peak areas and mass concentrations of 36 pesticides were kept in definite ranges, with detection limits (3S/N) in the range of 0.001-0.006 mg·kg-1. Test for recovery was made by the standard addition method, giving results in the range of 61.3%-104%, with RSDs (n=6) of the determined values less than 12%. This method could be used to determine the residues of 36 pesticides in 20 actual fruit and vegetable juices, and carbofuran, imidacloprid, carbendazim, oxytetracycline, and clotrimazole were detected in some samples, with the detection amounts in the range of 0.010-0.034 mg·kg-1.

       

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