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    QuEChERS提取-超高效液相色谱-串联质谱法测定蔬菜中氨基甲酸酯类农药的残留量

    Determination of Carbamate Pesticides Residues in Vegetables by UPLC-MS/MS with QuEChERS Extraction

    • 摘要: 将蔬菜样品粉碎匀浆后于-20℃保存备用。取此样品10.00 g与含1.3%(体积分数)甲酸溶液的乙腈10 mL充分混匀后超声提取20 min,加入无水硫酸钠8.2 g作为脱水剂,氯化钠3.0 g作为盐析剂,混合后离心5 min。取出上清液并保留。对留下的样品按上述方法重复提取1次。将2次所得上清液合并,并从中分取2.0 mL溶液,加入吸附剂N-丙基乙二胺(PSA)0.4 g,C18 0.25 g和石墨化碳黑(GCB)8.2 mg,涡旋振荡2 min进行净化处理,随即离心2 min,取上清液经0.22 μm滤膜过滤。取滤液,按超高效液相色谱-串联质谱法测定其中6种氨基甲酸酯类农药的残留量。用Agilent Poroshell 120 EC-C18色谱柱为固定相,进样量为5 μL。用由不同比例的(A)20 mmol·L-1乙酸铵溶液(每升中含乙酸1 mL)和(B)乙腈组成混合液作为流动相进行梯度洗脱。串联质谱分析选择电喷雾离子源和多反应监测模式。所测定的6种氨基甲酸酯类农药的工作曲线的线性范围均为0.200~100 μg·L-1,并测得其检出限(3S/N)为0.08~0.38 μg·kg-1。按标准加入法进行回收试验,测得回收率为81.0%~111%,测定值的相对标准偏差(n=6)为2.8%~4.9%。

       

      Abstract: Vegetable samples were homogenized and kept at -20℃ separately for use as analytical samples. 10.00 g of the homogenized sample were mixed with 10 mL of a mixture of acetonitrile containing 1.3% (volume fraction) formic acid, and extracted ultrasonically for 20 min. After adding 8.2 g of anhydrous sodium sulfate (as dehydrator) and 3.0 g of sodium chloride (as salting-out agent), the mixture was centrifuged for 5 min. The supernatant was separated and preserved. The sample was extracted once more as described above. The supernatants were combined, and an aliquot of 2.0 mL was taken and purified by swirling with 0.4 g of PSA, 0.25 g of C18 and 8.2 mg of GCB for 2 min, and then centrifuged for 2 min. The supernatant was taken and filtered through 0.22 μm filtering membrane. The filtrate was used as testing solution for determination of residual amounts of the 6 carbamate pesticides by UPLC-MS/MS. In UPLC separation, Agilent Poroshell 120 EC-C18 column was used as stationary phase and mixtures in various ratios of (A) 20 mmol·L-1 NH4OAc solution (containing 1 mL of acetic acid perliter) and (B) acetonitrile were used as mobile phases in programed gradient elution. ESI and MRM mode were adopted in MS/MS. Linear relationships were found between values of peak areas of the 6 carbamate presticides and the respective mass concentrations in the same range of 0.200-100 μg·L-1, with their detection limits (3S/N) in the range of 0.08-0.38 μg·kg-1. Test for recovery was made by standard addition method, giving results in the range from 81.0% to 111%, and values of RSDs (n=6) ranged from 2.8% to 4.9%.

       

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