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    QuEChERS结合气相色谱-串联质谱法和液相色谱-串联质谱法测定豇豆制品中69种农药的残留量

    Determination of 69 Pesticide Residues in Cowpea Products by Gas Chromatography-Tandem Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry Combined with QuEChERS

    • 摘要: 豇豆因其生长习性和种植环境的特殊性,易发生农药残留问题,而生产、加工酸豆角和干豆角制品时也会引入农药,进一步增加了豇豆制品的潜在食品安全风险,但是豇豆制品中农药残留检测方法的研究比较缺乏,因此提出了题示方法。将酸豆角、干豆角样品粉碎后,分取10 g酸豆角样品(分取5 g干豆角样品,加入5 mL水),加入10 mL乙腈,涡旋提取2 min。加入1颗陶瓷均质子和一个含4 g硫酸镁、1 g氯化钠、1 g柠檬酸钠和0.5 g柠檬酸氢二钠的QuEChERS萃取盐包,涡旋提取2 min,离心2 min。将上清液置于含900 mg无水硫酸镁、150 mg N-丙基乙二胺(PSA)和15 mg石墨化碳黑(GCB)的QuEChERS净化管中,涡旋1 min,离心2 min。分取1 mL上清液,过0.22 μm有机滤膜,滤液用液相色谱-串联质谱法(LC-MS/MS)分析;取1 mL上清液,于40 ℃氮吹至近干,加入1 mL丙酮,涡旋30 s,过0.22 μm有机滤膜,滤液用气相色谱-串联质谱法(GC-MS/MS)分析。在GC-MS/MS分析中,41种农药在Thermo TG-5SILMS色谱柱上以程序升温条件分离,以电子轰击离子(EI)源电离,多反应监测(MRM)模式检测,基质匹配法定量;在LC-MS/MS分析中,28种农药在ACQUITY UPLC BEH C18色谱柱上用不同体积比的含0.01%(体积分数,下同)甲酸的5 mol·L−1乙酸铵溶液和含0.01%甲酸的甲醇溶液的混合溶液进行梯度洗脱分离,以电喷雾离子源正离子(ESI+)模式电离,MRM模式检测,基质匹配法定量。结果显示,各农药的质量浓度分别在0.010~0.400 mg·L−1内(GC-MS/MS)和0.005~0.150 mg·L−1内(LC-MS/MS)和峰面积呈线性关系,相关系数均大于0.998 0,测定下限(10S/N)为0.01 mg·kg−1。按标准加入法进行回收试验,回收率为70.6%~117%,测定值的相对标准偏差(n=6)为0.45%~7.0%。方法用于26批酸豆角和22批干豆角样品的分析,阳性样品检出率高达81.2%,检出的农药多达57种。

       

      Abstract: Cowpea is prone to pesticide residues due to its growth habits and unique planting environment, while pesticides are also introduced when producing and processing sour and dry bean products, further increasing the potential food safety risks of cowpea products. However, research on pesticide residue detection methods of cowpea products lacked, so the title method was proposed. After crushing the sour and dry bean samples, 10 g of sour bean sample was taken (5 g of dry bean sample was taken, and 5 mL of water was added), and 10 mL of acetonitrile was taken. The mixture was extracted by vortex for 2 min, and 1 ceramic average proton and a QuEChERS extraction salt package containing 4 g of magnesium sulfate, 1 g of sodium chloride, 1 g of sodium citrate, and 0.5 g of disodium hydrogen citrate were added. The mixture was extracted by vortex for 2 min, and centrifuged for 2 min. The supernatant was placed into a QuEChERS purification tube containing 900 mg of anhydrous magnesium sulfate, 150 mg of PSA, and 15 mg of GCB, and the tube was vortexed for 1 min, and centrifuged for 2 min. An aliquot (1 mL) of the supernatant was passed through a 0.22 μm organic filter membrane, and the filtrate was analyzed by LC-MS/MS. An aliquot (1 mL) of the supernatant was taken, and blown to near dryness by nitrogen at 40 ℃. After 1 mL of acetone was added, the mixture was vortexed for 30 s, and passed through a 0.22 μm organic filter membrane, and the filtrate was analyzed by GC-MS/MS. In GC-MS/MS analysis, the 41 pesticides were separated on Thermo TG-5SILMS chromatographic column under temperature programmed conditions, ionized by EI source, detected by MRM mode, and quantified by matrix matching method. In LC-MS/MS analysis, the 28 pesticides were separated by gradient elution on ACQUITY UPLC BEH C18 column with mixed solutions composed of 5 mol · L−1 ammonium acetate solution containing 0.01% (volume fraction, the same below) formic acid and methanol solution containing 0.01% formic acid at different volume ratios, ionized by ESI+ mode, detected by MRM mode, and quantified by matrix matching method. It was shown that linear relationships between values of the mass concentration and peak area of pesticides were kept in the ranges of 0.010-0.400 mg · L−1 for GC-MS/MS and 0.005-0.150 mg · L−1 for LC-MS/MS, with correlation coefficients greater than 0.998 0, and lower limits of determination (10S/N) of 0.01 mg · kg−1. Test for recovery was made according to standard addition method, giving recoveries in the range of 70.6%-117%, and RSDs (n=6) of the determined values ranged from 0.45% to 7.0%. The proposed method was applied to the analysis of 26 batches of sour samples and 22 batches of dry bean samples, the detection rate of the positive samples was up to 81.2%, and the number of pesticides detected was up to 57 kinds.

       

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