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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 OnGuardⅡRP柱和Dionex OnGuardⅡAg/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。
Objective To establish a simple and rapid method for the determination of glyphosate residues in tea by ion chromatography. Methods After the sample was extracted with water, acetonitrile was used to precipitate anionic impurities. After centrifugation, the supernatant was passed through a Dionex OnGuard ⅡRP column and a Dionex OnGuard Ⅱ Ag / H column, separated by IonPac AS11-HC column (AG11-HC containing) Eluent automatic generator (EG) for gradient elution, suppressor using additional water mode, conductivity detector detection. Results The linearity of glyphosate in the range of 0.006 ~ 12.5 mg / L was good (the correlation coefficient was 0.9998). The detection limit was 0.19 mg / kg, the limit of quantification was 0.64 mg / kg and the recovery was 80.7% ~ 98.1% , Intraday precision (n = 6) was 1.8% -3.4%, daytime precision (n = 5) was less than 5%. Conclusion The method has the characteristics of good purification effect, accurate quantification, quick and sensitive. It is suitable for the determination of glyphosate residues in tea and can meet the test requirements of GB 2763-2014.