QuEChERS-液相色谱串联质谱法测定复杂基质蔬菜中四聚乙醛残留量

Determination of metaldehyde residues in complex matrix vegetables by QuEChERS and LC-MS/MS

用改进的QuEChERS提取净化法结合液相色谱串联质谱,建立了测定复杂基质蔬菜中四聚乙醛残留量的方法。样品经乙腈提取后,取2 mL上清液与MgSO_4(300 nag)、PSA(100 mg)和GCB(100 mg)(仅韭菜)吸附净化剂涡旋振荡1 min,再离心5 min(3 000 r/min);取上清液过0.22μm有机膜,由LC-MS/MS检测。分析采用Agilent ZORBAX Eclipse Plus C_(18)色谱柱分离,乙腈-0.1%甲酸水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。研究结果表明:四聚乙醛在0.002-1.00 mg/L浓度范围内呈良好的线性,线性相关系数大于0.999;方法检出限为0.002 mg/kg;定量限为0.01 mg/kg。添加浓度为0.01 mg/kg、0.10 mg/kg、1.00 mg/kg时,平均回收率在71.6%—92.1%;相对标准偏差为2.39%—4.48%。用液相色谱串联质谱检测法检测复杂基质蔬菜中的四聚乙醛前处理简便、可靠,灵敏度和准确度均达到了农药残留检测的要求。

A method to determine metaldehyde residues in complex matrix vegetables was established by the improved QuEChERS extraction method in combination with liquid chromatography-tandem mass spectrometry （LC-MS/MS）. The metaldehyde residues in complex matrix vegetables were extracted by acetonitrile, and the su- pernate （2 mL） was mixed with MgSO4 （ 300 rag）, PSA （ 100 mg and GCB （ 100 rag） and then was vortically os- cillated for 1 min and centrifuged for 5 rain at 3 000 r/min; The supernatant fluid was filtered through 0.22-μm organic membrane and then analyzed by LC-MS/MS on an Agilent ZORBAX Eclipse Plus C18 column and aceto- nitrile-0.1% formic acid solution as mobile phase in which the sample was collected with positive ion electros- pray ionization （ ESI ＋ ） model and multiple reaction monitoring （MRM） mode and quantified by an external standard method. The results showed that there was a good linearity within 0. 002--1.00 mg/L metaldehyde and the linear correlation coefficient was greater than 0. 999 ; the detection limit was 0. 002 mg/kg and the quantita- tion limit was 0.01 mg/kg; when spiked at 0.01 mg/kg,0.10 mg/kg and 1.00 mg/kg the average recovery rate was 71.6%--92.1%, and the relative standard deviation was 2.39%--4.48%. The test also indicated that de- termination of metaldehyde residues in complex matrix vegetables by QuEChERS and LC-MS/MS was simple and reliable in pretreatment, and its sensitiveness and accuracy all met the requirements for determination of pesticide residues.