离子色谱法测定茶叶中草甘膦的残留

Determination of glyphosate residues in tea by ion chromatography

中文关键词:  离子色谱法  电导检测  草甘膦  茶叶  固相萃取净化

英文关键词:ion chromatography  conductivity detection  glyphosate  tea  solid phase extraction

中文摘要:

      目的 建立一种简单、快捷测定茶叶中草甘膦残留量的离子色谱分析方法。方法 样品经水提取后使用乙腈沉淀阴离子杂质, 离心后取上清液依次过Dionex OnGuard Ⅱ RP柱和Dionex OnGuard Ⅱ Ag/H 柱, 经IonPac AS11-HC离子色谱柱(含AG11-HC保护住)分离, 用KOH淋洗液自动发生器(EG)进行梯度淋洗, 抑制器采用外加水模式, 电导检测器检测。结果 草甘膦在0.006~12.5 mg/L范围内线性关系良好(相关系数为0.9998), 方法的检出限为0.19 mg/kg, 定量限为0.64 mg/kg, 回收率为80.7%~98.1%, 日内精密度(n=6)为1.8%~3.4%, 日间精密度(n=5)小于5%。结论 该方法具有净化效果好、定量准确、灵敏快速的特点, 适用于茶叶中草甘膦残留的检测确证, 能达到GB 2763-2014的检测要求。

英文摘要:

      Objective To establish a rapid and simple analytical method for the determination of glyphosate residues in tea by ion chromatography. Method The anionic impurities in the extraction solution were precipitated with acetonitrile. The large molecules and Cl- in the supernatant were removed by the Dionex OnGuard Ⅱ RP column and the Dionex OnGuard Ⅱ Ag/H column, respectively. The filtrate was separated on an IonPac AS-11 column with KOH solution as eluent. A suppressor with external water mode and a conductivity detector were used for the detection. Results Under the experimental conditions, the calibration curve of glyphosate was linear in the range of 0.006~12.5 mg/L, with a correlation coefficient of 0.9998. The limits of detection (LODs) and the limits of quantitation of the method (LOQs) were 0.19 mg/kg and 0.64 mg/kg, respectively. The mean recoveries of glyphosate in spiked tea ranged from 80.7% to 98.1% with the intra-day precisions (n=6) in the range of 1.8%~3.4% and inter-day precisions (n=5) less than 5%. Conclusion This method can meet the requirement of GB 2763-2014 and be suitable for the identification and quantification of glyphosate in tea due to its simplicity and accuracy.