QuEChERs法结合气相色谱检测大米中的有机磷农药

Determination of Organophosphorus Pesticide Residues in Rice by QuEChERs-Gas Chromatography Method

研究采用改良的QuEChERS样品前处理法结合气相色谱-电子捕获检测器(gas chromatography with an electron capture detector,GC-ECD)检测大米中的乙酰甲胺磷、乐果、马拉硫磷和毒死蜱.样品经乙腈提取,加入50 mg PSA和50 mg C18分散固相净化,进GC-ECD检测,外标法定量.4种有机磷农药在0.01~2 mg/L范围内呈现良好的线性关系,相关系数为0.992 3~0.999 6;样品在4个添加水平(0.01 mg/kg、0.05 mg/kg、0.1mg/kg、0.5 mg/kg)下的回收率为70.95%~113.49%,相对标准偏差为1.05%~19.10%,检出限为0.02 mg/L,定量限为0.01 mg/kg.将该方法应用于肇庆地区市售15种大米中有机磷农药残留量检测,结果表明食用大米中乙酰甲胺磷、乐果、马拉硫磷、毒死蜱的残留量均低于GB 2763-2019食品安全国家标准《食品中农药最大残留限量》.该方法样品前处理简单,准确性好,灵敏度高,能够满足大米中有机磷农药残留量检测要求.

The improved QuEChERS sample pretreatment method combined with gas chromatography was used to detect acephate,dimethoate,malathion,and chlorpyrifos in rice.The sample was extracted with acetonitrile,purified by adding 50 mg PSA and 50 mg C18,detected by GC-ECD and quantified by external standard method.The four organophosphorus pesticides showed a good linear relationship in the range of 0.01-2 mg/L,and the correlation coefficient was 0.992 3-0.999 6.The recoveries of the four organophosphorus pesticides at four fortified levels(0.01 mg/kg,0.05 mg/kg,0.1 mg/kg and 0.5 mg/kg) were 70.95% ~113.49%.The relative standard deviation was 1.05%~19.10%.The detection limit was 0.02 mg/L and the quantitative limit was 0.01 mg/kg.The method was applied to determine organophosphorus pesticide residues in 15 kinds of rice sold in Zhaoqing area.The results showed that the residues of acephate,dimethoate,malathion and chlorpyrifos in edible rice were lower than the maximum residue limit of pesticides in food according to the national food safety standard GB 2763-2019.The method has the advantages of simple sample pretreatment,good accuracy and high sensitivity,and can meet the detection requirements of organophosphorus pesticide residues in rice.