离子色谱法测定不同谷物中草甘膦残留

Determination of glyphosate residues in different kinds of grains by ion chromatography

目的建立离子色谱法测定玉米、全麦、小米和燕麦等谷物中草甘膦残留量的方法。方法样品经水提取后采用乙酸沉淀蛋白质,经固相萃取小柱(SPE小柱)纯化,取净化液进行离子色谱分析。采用Ion Pac AS16阴离子分析柱和电导检测器,确定了以氢氧化钾(KOH)溶液作为淋洗液进行梯度洗脱、柱温30℃,淋洗液流速1.0 mL/min的优化条件。结果在0.25~5.00μg/mL浓度范围内,空白基质和4种谷物基质(玉米、全麦、小米和燕麦)草甘膦线性关系良好(r^2>0.999)。在2.5、5.0、10 mg/kg添加水平下,4种谷物基质(玉米、全麦、小米和燕麦)中草甘膦回收率均为80.3%~103.5%,相对标准偏差(relative standard deviation,RSD)为2.7%~4.9%(n=6),方法检出限为0.70~1.50 mg/kg(S/N=3)。结论该方法简便快速、准确度和精密度高、检出限低,适用于谷物中草甘膦的测定。

Objective To establish an analysis method for determination of glyphosate residues in corn, whole wheat, millet and oat by ion chromatography （IC）. Methods The grain samples were extracted by water and the protein was precipitated by acetic acid. After purification with SPE columns, the purified solutions were injected into ion chromatography to determine the glyphosate content in the samples. The glyphosate was separated on a IonPac AS 16 anion column following conductivity detector with KOH solution as eluent at flow rate of 1.0 mL/min and kept at 30 ~C. Results Glyphosate residues showed good linearity with correlation coefficient （r2） greater than 0.999 in the concentration range of 0.25-5.00 μg/mL in the blank matrice and 4 representative matrices （corn, whole wheat, millet and oat）. The recovery rates ranged from 80.3% to 103.5% at the spiked levels of 2.5, 5.0, 10 mg/kg, and RSDs ranged from 2.7% to 4.9% （n=6）. The method detection limit （MDL） of glyphosate residues ranged from 0.70 to 1.50 mg/kg （S/N=3）. Conclusion This method has advantages of rapidity, simplicity, high accuracy, high precision and low limit of detection, which is suitable for the analysis of glyphosate residues in different kinds of grains.