分散固相萃取净化果蔬中四聚乙醛残留量的LC-MSMS测定

建立了改进的分散固相萃取(DSPE)提取净化、测定水果和蔬菜中四聚乙醛残留量的液相色谱串联质谱方法。前处理过程:样品经乙腈提取后,取2mL上清液与PSA(100mg),和MgSO4(300mg)吸附净化剂涡旋振荡1min;再离心5min(3 000r/min);取全部上清液过0.22μm有机膜,由LC-MSMS检测。分析采用Agilent ZORBAX Eclipse Plus C18色谱柱分离,乙腈-0.1%甲酸溶液作为流动相洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,外标法定量。四聚乙醛在0.002~1.00mg/L浓度范围内呈良好的线性,线性相关系数0.99;方法检出限为0.002 5mg/kg;定量限为0.01mg/kg。添加浓度为0.01、0.10、1.0 mg/kg时,平均回收率在83.7%~116.4%之间;相对标准偏差为0.81%~6.21%。

Determination of Metaldehyde Residues in Vegetables and Fruits by DSPE and Liquid Chromatography with Tandem Mass Spectrometry

In this paper, a modified method of DSPE for the determination of metaldehyde residues in vegetables and fruits by LC-MSMS was established. The pretreatment procedure went like the following： Firstly, the target pesticide residues were extracted by pure acetonitrile. Then,2mL of supernatant was mixed with PSA（100mg） and MgSO4（300mg）, and vortexed for 1min and centrifuged for 5mins（3 000r/min）. Finally, the supernatant was filtered through 0.22μm of organic membrane and injected into LC-MSMS. The samples were analyzed by LC-MS/MS on an Agilent ZORBAX Eclipse Plus C18 column with a mixture of acetonitrile and 0.1% formic acid solution as the mobile phase. The samples were collected with positive ions electrospray ionization（ESI＋） model and multiple reaction monitoring（MRM） mode, and quantified with external standard method. Good linearity was obtained for metaldehyde at the concentration range of0.002 5～1.0mg/L with a line correlative coefficient more than 0.99. The recoveries of metaldehyde in three kinds of vegetables and three kinds of fruits were 83.7%～116.4% at the fortified levels of 0.01 ～1.0mg/kg with a limit of detection of 0.002 5mg/kg and a limit of quantification of 0.01mg/kg. The relative standard deviations were less than 6.21%.