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

将蔬菜样品粉碎匀浆后于-20℃保存备用。取此样品10.00g与含1.3%(体积分数)甲酸溶液的乙腈10mL充分混匀后超声提取20min,加入无水硫酸钠8.2g作为脱水剂,氯化钠3.0g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2.0mL溶液,加入吸附剂N-丙基乙二胺(PSA)0.4g,C180.25g和石墨化碳黑(GCB)8.2mg,涡旋振荡2min进行净化处理,随即离心2min,取上清液经0.22μm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 120EC-C18色谱柱为固定相,进样量为5μL。用由不同比例的(A)20mmol·L^-1乙酸铵溶液(每升中含乙酸1mL)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0.200~100μg·L^-1,并测得其检出限(3S/N)为0.08~0.38μg·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%。

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

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 0.22μm filtering membrane.The filtrate was used as testing solution for determination of residual amounts of the6 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 0.200-100μg·L^-1,with their detection limits(3 S/N)in the range of 0.08-0.38μg·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%.