QuEChERS结合气相色谱-串联质谱法测定西洋参中53种常见农药的残留量

Determination of Residues of 53Common Pesticides in American Ginseng by Gas Chromatography-Tandem Mass Spectrometry Combined with QuEChERS

取西洋参粉末约2 g,加入1%(体积分数)冰乙酸溶液10 mL,均质5 min,加入体积比3∶1的乙腈-甲苯混合溶液10 mL和混合内标(由磷酸三苯酯、倍硫磷-d6和阿特拉津-d5组成)储备溶液1 mL,振荡1 min。加入质量比4∶1的无水硫酸镁-无水乙酸钠混合粉末7.5 g,振荡3 min,冰水浴冷却10 min,离心5 min。分取上清液9 mL置于装有无水硫酸镁900 mg、N-丙基乙二胺(PSA)300 mg、C18300 mg、硅胶300 mg和石墨化碳黑(GCB)45 mg的净化管中,涡旋1 min,振荡5 min,离心1 min。上清液用0.22μm滤膜过滤。取续滤液1 mL,加入分析保护剂(由D-(+)-核糖酸-1,4-内酯和山梨醇组成)溶液0.3 mL,用乙腈定容至2 mL,供气相色谱-三重四极杆质谱仪分析。各目标物在SH-Rxi-5Sil MS色谱柱上用程序升温条件分离,以电子轰击离子(EI)源电离,多反应监测模式检测,基质匹配法联合内标法定量。结果显示,53种农药工作曲线的线性范围均为2.5~200μg·L^(-1),检出限(3S/N)为0.001~0.002 mg·kg^(-1);按标准加入法进行回收试验,回收率为69.1%~107%,测定值的相对标准偏差(n=6)均小于10%。方法用于50批进口西洋参样品的分析,检出了p,p′-滴滴伊、o,p′-滴滴涕、p,p′-滴滴滴、p,p′-滴滴涕和五氯硝基苯,西洋参的农药污染风险整体可控。

About 2g of American ginseng powder was taken,and 10mL of 1%(volume fraction)glacial acetic acid solution was added.The mixture was homogenized for 5min,and 10mL of acetonitrile-toluene mixed solution at volume ratio of 3∶1,and 1 mL of mixed internal standards(consisting of triphenyl phosphate,parathion-d6and atrazine-d5)stock solution were added.The mixture was shaken for 1min,and 7.5g of mixed powder composed of anhydrous magnesium sulfate and anhydrous sodium acetate at mass ratio of 4∶1was added.The mixture was shaken for 3min,cooled in ice water bath for 10min,and centrifuged for 5min.An aliquot(9mL)of the supernatant was taken and placed into a purification tube containg 900mg of anhydrous magnesium sulfate,300mg of PSA,300mg of C18,300mg of silica gel and 45mg of GCB,and the mixture was vortexed for 1min,shaken for 5 min,and centrifuged for 1 min.The supernatant was passed through a 0.22μm filter membrane,and 1mL of the continued filtrate was taken,and mixed with 0.3mL of analyte protectant solution composed of D-(+)-riboacid-1,4-lactone and sorbitol.The mixed solution was made its volume up to 2mL by acetonitrile,which was introduced into gas chromatograph-triple quadrupole mass spectrometer for analysis.The targets were separated on SH-Rxi-5Sil MS column under temperature programmed conditions,ionized by electron impact ion source,detected by multiple reaction monitoring mode,and quantified by matrix matching method combined with internal standard method.As shown by the results,the same linear range of working curves of 53 pesticides was 2.5-200μg·L^(-1),with detection limits(3S/N)in the range of 0.001-0.002mg·kg^(-1).Test for recovery was made according to standard addition method,giving results in the range of 69.1%-107%,and RSDs(n=6)of the determined values were less than 10%.The proposed method was applied to the analysis of 50batches of imported American ginseng samples,and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene,2,4′-dichlorodiphenyltrichloroethane,1,1-dichloro-2,2-bis(4-chlorophenyl)-ethane,1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane and pentachloronitrobenzene were detected,and the overall risk of pesticide pollution in American ginseng was controllable.