分散固相萃取—液相色谱串联质谱法测定柑橘中的2,4-二氯苯氧乙酸

Determination of 2,4-dichlorophenoxyacetic acid in citrus fruit by liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction

建立了柑橘中2,4-二氯苯氧乙酸(2,4-D)的分散固相萃取—液相色谱串联质谱分析方法。样品经乙腈匀浆提取,提取液在酸性条件下经盐析,乙二胺基-N-丙基(PSA)分散固相萃取净化,采用XDB-C18液相色谱柱,以乙酸铵甲醇溶液和水溶液为流动相,洗脱分离后,目标分析物在选择反应监测(SRM)模式下进行定性和定量分析。2,4-D在0.05～1.60 ng.mL-1范围内线性良好,方法检出限为0.002 ng.mL-1,定量限为0.008 mg.kg-1;在0.10,0.20和0.40 mg.kg-1三个添加水平下回收率为76.5%～95.3%,相对偏差小于10%。该方法准确、灵敏、高效、环保,适用于柑橘等水果中2,4-D残留量的测定。

A high performance liquid chromatography tandem mass spectrometric（HPLC-MS/MS） method was developed for 2,4-D residues in citrus.The samples were extracted with acetonitrile,salted out in acid condition,and then cleaned up by dispersive solid-phase extraction with dispersant sorbent of primary secondary amine（PSA）.The separation of 2,4-D was performed on a XDB-C18（4.6 mm×50 mm,1.8 μm）column using a mixture of ammonium acetate methanol and water solution as mobile phase.The qualitative and quantitative analysis for the analyte were carried out under the selective reaction monitoring（SRM）mode with negative electrospray ionization.Under the optimal conditions,the calibration curves were linear in the range of 0.05-1.60 ng·mL-1 for 2,4-D,the limit of detection was 0.002 mg·kg-1,and the limit of quantification was 0.008 mg·kg-1.The average spiked recoveries at 0.10 mg·kg-1,0.20 mg·kg-1 and 0.40 mg·kg-1 addition concentration were between 76.5% and 95.3% with relative standard deviations（RSDs）less than 10%.The proposed method is accurate,sensitive and high-efficient,and applicable for the determination of 2,4-D in citrus.