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    自制Co3O4多孔材料净化-气相色谱法测定蔬菜中4种有机磷农药的残留量

    Determination of Residues of 4 Organophosphorus Pesticides in Vegetables by Gas Chromatography after Purification with Self-Made Co3O4 Porous Material

    • 摘要: 以题示方法测定蔬菜样品中磷胺、倍硫磷、喹硫磷、丙溴磷等4种有机磷农药的残留量。采用硝酸钴和甘氨酸燃烧法制备Co3O4多孔材料,通过粉末X射线衍射仪(XRD)、场发射电子扫描显微镜(FESEM)、吸附比表面测试(BET)、热重分析(TG)对材料进行了表征,结果表明,该净化剂为具有层状疏松多孔结构的尖晶石型Co3O4材料,比表面积为22.054 m2·g-1,Co3O4的质量分数为87.0%。蔬菜样品经切碎、研磨后,分取2.5 g,用甲苯5.0 mL涡旋提取5 min。离心,分取4.0 mL上清液,加入0.07 g Co3O4多孔材料,涡旋净化5 min。离心,分取0.6 mL上清液,过0.22 μm滤膜,滤液进入气相色谱仪,在HP-5毛细管色谱柱上用程序升温条件分离,用火焰光度检测器测定。结果显示,Co3O4多孔材料的用量仅为QuEChERS法的百分之一;4种有机磷农药均在15 min内实现了基线分离,磷胺还实现了顺反异构的拆分和分离;标准曲线的线性范围分别为0.032~0.60 mg·L-1(磷胺和丙溴磷)和0.016~0.30 mg·L-1(倍硫磷和喹硫磷),检出限(3S/N)为0.004~0.010 mg·L-1。对空白油麦菜样品进行4个浓度水平的加标回收试验,4种有机磷农药的回收率为89.2%~95.8%,测定值的相对标准偏差(n=6)均不大于7.0%;方法用于11种蔬菜样品的分析,均未检出4种有机磷农药的残留,符合GB 2763-2021的规定。

       

      Abstract: The residues of the 4 organophosphorus pesticides (phosphamidon, fenthion, quinalphos and profenofos) in vegetable samples were determined by the method mentioned by title. Porous material of Co3O4 was prepared by the combustion of Co(NO3)2 and glycine, and characterized by XRD, FESEM, BET and TG. As found by results, the purifier was spinel-type Co3O4 material with layered loose porous structure, its specific surface area was 22.054 m2·g-1, and mass fraction of Co3O4 was 87.0%. After chopping and grinding, 2.5 g of vegetable samples were extracted with 5.0 mL of toluene by vortex. After centrifugation, 0.07 g of Co3O4 porous material was added into 4.0 mL of supernatant, and the mixture was vortexed for 5 min. After centrifugation, an aliquot (0.6 mL) of the supernatant was taken out and passed through a 0.22 μm filter membrane. The filtrate was introduced into the gas chromatography, the 4 pesticides were separated on the HP-5 capillary column with temperature program, and detected by flame photometric detector. It was shown that the amount of porous material of Co3O4 was only 1% of that of QuEChERS method. A baseline separation of the 4 organophosphorus pesticides was achieved within 15 min, and the cis-and trans-isomers of phosphamidon were also separated. The linear ranges of standard curves were 0.032-0.60 mg·L-1 (for phosphamidon and profenofos) and 0.016-0.30 mg·L-1 (for fenthion and quinalphos), with detection limits (3S/N) of 0.004-0.010 mg·L-1. Test for the spiked recovery was made on the blank rapeseed samples at the 4 concentration levels, giving recoveries of the 4 organophosphorus pesticides in the range of 89.2%-95.8%, and RSDs (n=6) of the determined values were not more than 7.0%. The proposed method was applied to the analysis of 11 kinds of vegetable samples, and the residues of the 4 organophosphorus pesticides were not detected, which met the requirements of GB 2763-2021.

       

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