提出了加速溶剂萃取(ASE)-凝胶渗透色谱法(GPC)净化-气相色谱-串联质谱法(GC-MS/MS)测定农作物土壤中甲基内吸磷、辛硫磷、蝇毒磷、灭线磷和二溴磷等5种有机磷类农药残留量的方法。随机采集农作物土壤样品,去除大颗粒杂质,自然风干,用粉碎机粉碎,过0.3 mm筛网。称取过筛后的土壤样品10 g于加速溶剂萃取池中,加入硅藻土12 g,以体积比为1∶1的丙酮-正己烷混合液为萃取剂,采用ASE反复萃取3次;将收集到的萃取液转移至GPC净化瓶中,经GPC浓缩净化并氮吹至近干,用1 mL甲醇溶解,0.45 μm滤膜过滤,滤液供GC-MS/MS分析,外标法定量。结果显示:5种农药的质量浓度在0.02~10.00 mg·L^-1内与其对应的峰面积呈线性关系,检出限(3S/N)为1.6~3.2 μg·kg^-1;对阴性样品进行3个浓度水平的加标回收试验,5种农药的回收率为90.0%~101%;对6份阴性样品的加标溶液进行测定,5种农药测定值的相对标准偏差为2.8%~4.2%;方法用于实际农作物土壤样品分析,甲基内吸磷、辛硫磷、灭线磷均被不同程度地检出。

A method for the determination of residues of 5 organophosphorus pesticides (including of demeton methyl, phoxim, coumaphos, ethoprophos and naled) in crop soil by gas chromatography-tandem mass spectrometry (GC-MS/MS) with accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) purification was proposed. Crop soil sample was randomly collected and passed through 0.3 mm screen mesh after removing large particle impurities and crushing. Screened soil sample (10 g) was placed in the accelerated solvent extraction tank, and 12 g of diatomite was added. The above solution was repeatedly extracted 3 times by ASE with a mixture of acetone and hexane at volume ratio of 1∶1. The collected extracted solution was transferred to GPC purification bottle, and then concentrated and purified by GPC. The purified solution was blown to near dry by nitrogen, and then dissolved with 1 mL of methanol and filtered by 0.45 μm filter membrane. The filtrate was analyzed by GC-MS/MS, and external standard method was used for quantification. As shown by the results, linear relationships between values of mass concentrations of 5 pesticides and their peak areas were kept in the same ranges of 0.02-10.00 mg·L^-1, with detection limits (3S/N) in the range of 1.6-3.2 μg·kg^-1. Test for recovery was made on negative sample at 3 concentration levels by standard addition method, giving results of 5 pesticides in the range of 90.0%-101%. 6 spiked solutions of negative sample were determined, and RSDs of the determined values of 5 pesticides were in the range of 2.8%-4.2%. This method has been applied to the analysis of actual crop soil samples, and demeton methyl, phoxim, ethoprophos were detected in varying degrees.