Li Weiwei, Morgan Marsha K, Graham Stephen E, Starr James M
Oak Ridge Institute for Science and Education Fellow at the U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park, NC 27711 USA.
U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, USEPA MD D205-05, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711 USA.
Talanta. 2016 May 1;151:42-50. doi: 10.1016/j.talanta.2016.01.009. Epub 2016 Jan 11.
Pyrethroid insecticides are used extensively in agriculture, and they, as well as their environmental degradates, may remain as residues on foods such as fruits and vegetables. Since pyrethroid degradates can be identical to the urinary markers used in human biomonitoring, it is important to understand the contribution of these degradates when studying sources of human pyrethroid exposure. We modified the widely used Quick Easy Cheap Effective Rugged Safe (QuEChERS) method to measure several current-use pyrethroids (cis/trans-permethrin, cypermethrin, deltamethrin, esfenvalerate, bifenthrin, cyfluthrin, and cyhalothrin) and their environmental degradation products (3-PBA, cis/trans-DCCA, 4-F-3-PBA, DBCA, and MPA) in selected fresh fruits and vegetables. Using fortified samples, we determined extraction efficiencies from: tomatoes, oranges (whole, peeled, and rind), grapes, apples, bananas (peeled and rind only), onions, lettuce, green peppers, carrots and broccoli. For a subset of these food items (apples, grapes, tomatoes, lettuce and banana peel), we also established limits of detection (MDLs) and quantitation (MQLs). Each sample was homogenized (1kg) then spiked with the target pyrethroids and their degradation products. Sub-samples (15g) were extracted with acetonitrile, then salted out and partitioned with NaCl and MgSO4. The extract was divided and further cleaned using solid phase extraction (SPE) cartridges containing either graphitized non-porous carbon (pyrethroids) or C18 (degradation products). Sample analysis was via liquid chromatography/tandem mass spectrometry (LC-MS/MS). Considering the mean recoveries each of the 14 analytes in all 13 matrices: 42% of the recoveries were ≥90%, 70% were ≥80%, and 90% were ≥70%. All MDL's were less than 100ng/kg, except 3-PBA (132ng/kg, tomato), MPA (129ng/kg, tomato), and trans-permethrin (141ng/kg, banana peel). We then applied the method to non-spiked samples (subset of 5 for which the MDLs/MQLs had been determined) collected weekly for four weeks from local supermarkets. At least one pyrethroid was present in measureable concentrations in all matrices except banana peels. In contrast, the only degradation products detected were cis/trans-DCCA, in one lettuce sample.
拟除虫菊酯类杀虫剂在农业中广泛使用，它们及其环境降解产物可能会残留在水果和蔬菜等食物上。由于拟除虫菊酯降解产物可能与人体生物监测中使用的尿液标志物相同，因此在研究人体拟除虫菊酯暴露源时，了解这些降解产物的贡献非常重要。我们改进了广泛使用的快速、简便、廉价、有效、耐用、安全（QuEChERS）方法，以测定选定新鲜水果和蔬菜中的几种现行使用的拟除虫菊酯（顺式/反式氯菊酯、氯氰菊酯、溴氰菊酯、乙氰菊酯、联苯菊酯、氟氯氰菊酯和氯氟氰菊酯）及其环境降解产物（3-苯氧基苯甲酸、顺式/反式二氯菊酸、4-氟-3-苯氧基苯甲酸、二溴菊酸和甲基吡啶磷）。使用加标样品，我们测定了以下样品的提取效率：西红柿、橙子（整个、去皮和果皮）、葡萄、苹果、香蕉（仅去皮和果皮）、洋葱、生菜、青椒、胡萝卜和西兰花。对于这些食品中的一部分（苹果、葡萄、西红柿、生菜和香蕉皮），我们还确定了检测限（MDL）和定量限（MQL）。每个样品（1kg）均进行均质化处理，然后加入目标拟除虫菊酯及其降解产物。子样品（15g）用乙腈提取，然后用氯化钠和硫酸镁进行盐析和分配。提取物分成两份，分别使用含有石墨化无孔碳（用于拟除虫菊酯）或C18（用于降解产物）的固相萃取（SPE）柱进一步净化。样品分析通过液相色谱/串联质谱（LC-MS/MS）进行。考虑到所有13种基质中14种分析物各自的平均回收率：42%的回收率≥90%，70%的回收率≥80%，90%的回收率≥70%。除3-苯氧基苯甲酸（132ng/kg，西红柿）、甲基吡啶磷（129ng/kg，西红柿）和反式氯菊酯（141ng/kg，香蕉皮）外，所有检测限均低于100ng/kg。然后，我们将该方法应用于从当地超市每周收集四周的未加标样品（已测定MDL/MQL的5个样品子集）。除香蕉皮外，所有基质中均检测到至少一种可测量浓度的拟除虫菊酯。相比之下，仅在一个生菜样品中检测到唯一的降解产物顺式/反式二氯菊酸。
