固相萃取/液相色谱-串联质谱法测定果蔬中草铵膦的残留量

Determination of Glufosinate Residue in Vegetables and Fruits by Liquid Chromatography-Tandem Mass Spectrometry with Purification of Solid Phase Extraction

建立了果蔬中草铵膦残留量的液相色谱-串联质谱（LC-MS/MS）分析方法。样品经水提取、二氯甲烷除去脂溶性杂质,强阳离子固相萃取小柱净化,9-芴甲基氯甲酸酯（FMOC-Cl）衍生后,以C18色谱柱（4.6 mm×50 mm,1.8μm）进行分离,5 mmol/L乙酸铵水溶液（含0.1%甲酸）-乙腈（含0.1%甲酸）作为流动相梯度洗脱,电喷雾正离子模式电离（ESI＋）,多反应监测模式（MRM）检测,内标法定量。方法在0~200μg/L浓度范围内线性关系良好,相关系数（r2）大于0.995。方法检出限为10μg/kg,定量下限为20μg/kg。在不同食品基质中,草铵膦在20,200,500μg/kg加标水平下的平均回收率为80.8%~102.2%,相对标准偏差（RSD）为1.8%~7.9%。该法采用同位素内标定量,有效地消除了样品基质效应,灵敏度高、准确度好,适用于果蔬中草铵膦残留量的监控测定。

A liquid chromatography- tandem mass spectrometric（ LC- MS/MS） method was established for the determination of glufosinate- ammonium residue in vegetables and fruits. The samples spiked with d3-glufosinate,the internal standard,were extracted with water,defatted with dichloromethane,and cleaned up using a strong cation exchange column,then derived with 9-fluorenylmethylchloroformate（ FMOC- Cl） overnight. The separation of the target compound was performed on a C18column（ 4. 6 mm × 50 mm,1. 8 μm） using 5 mmol/L ammonium acetate（ containing 0. 1% formic acid）- acetonitrile（ containing 0. 1% formic acid） as mobile phase. The identification and quantitation of glufosinate were performed by MS/MS in positive electrospray ionization（ ESI＋） and multiple reaction monitoring（ MRM） mode. The quantitative analysis was carried out by the internal standard method. The calibration curve showed a good linearity in the range of 0- 200 μg/L with a correlation coefficient greater than 0. 995. The limit of detection（ LOD） and the limit of quantitation（ LOQ） of this method were 10 μg /kg and 20 μg /kg,respectively. The average recoveries of glufosinate in foods at three spiked levels of 20,200,500 μg/kg were in the range of 80. 8%- 102. 2%with relative standard deviations（ RSDs） of 1. 8%- 7. 9%. The application of internal standard effectively reduced the influence of matrix effects. The results of validation tests indicated that the method was sensitive and accurate,and was suitable for the monitoring of glufosinate residue in vegetables and fruits.