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。

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.