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    固相萃取-气相色谱-串联质谱法测定土壤中7种嘧啶类杀菌剂的残留量

    Determination of Residues of 7 Pyrimidine Fungicides in Soil by Gas Chromatography-Tandem Mass Spectrometry with Solid Phase Extraction

    • 摘要: 土壤样品经除杂、碾碎、风干和过筛后,分取10 g,加入10 mL水(浸润样品),再加入5 g氯化钠和20 mL乙腈,混匀后离心3 min,取10 mL有机层以流量10 mL·min−1过活化好的HLB固相萃取柱,以体积比1∶1的甲醇-二氯甲烷混合溶液5 mL洗脱。收集洗脱液,于50 ℃氮吹至近干,残留物用1 mL乙酸乙酯溶解,过0.22 μm有机滤膜,滤液按照气相色谱-串联质谱法测定。在色谱分析中,以HP-5MS色谱柱为固定相,在柱升温程序下分离;在质谱分析中,以电子轰击离子源电离,多反应监测模式检测,外标法定量。结果显示,7种嘧啶类杀菌剂(嘧菌环胺、嘧菌腙、嘧霉胺、嘧菌酯、甲基嘧啶磷、氯苯嘧啶醇、嘧菌胺)的质量浓度在0.005~0.5 mg·L−1内和对应的定量离子峰面积呈线性关系,检出限(3S/N)为0.004 1~0.008 4 mg·kg−1。按照标准加入法进行回收试验,回收率为86.3%~110%,测定值的相对标准偏差(n=6)均小于5.0%。方法用于5份实际样品的分析,在2份样品中各检出了嘧菌环胺和嘧霉胺,检出量分别为0.032,0.051 mg·kg−1

       

      Abstract: After removing impurities, crushing, air drying, and sieving the soil sample, an aliquot (10 g) was taken, and 10 mL of water (infiltrating the sample) was added. Then, 5 g of sodium chloride and 20 mL of acetonitrile were added, and the mixture was mixed well and centrifuged for 3 min. The 10 mL of the organic layer was taken and passed through an activated HLB solid phase extraction column at a flow rate of 10 mL·min−1, and 5 mL of methanol-dichloromethane mixed solution at a volume ratio of 1∶1 was used for elution. The eluate was collected, and blown to near dryness at 50 ℃ with nitrogen. The residue was dissolved in 1 mL of ethyl acetate, and the solution was passed through a 0.22 μm organic filter membrane. The filtrate was determined by gas chromatography-tandem mass spectrometry. In chromatographic analysis, HP-5MS column was used as the stationary phase for separation under the column heating program. In mass spectrometry analysis, electron impact ion source was used for ionization, multiple reaction monitoring mode was used for detection, and external standard method was used for quantification. It was shown that linear relationships between values of the mass concentration and corresponding quantitative ion peak area of 7 pyrimidine fungicides (cyprodinil,pyraclostrobin,pyrimethanil,azoxystrobin,pirimiphos-methyl,fenarimol and mepanipyrim) were kept in the range of 0.005-0.5 mg·L−1, with detection limits (3S/N) in the range of 0.004 1-0.008 4 mg·kg−1. Test for recovery was made according to the standard addition method, giving recoveries in the range of 86.3%-110%, and RSDs (n=6) of the determined values were all less than 5.0%. The proposed method was used for the analysis of 5 actual samples, and cyprodinil and pyrimethanil were detected in two samples, with detection amounts of 0.032, 0.051 mg·kg−1, respectively.

       

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