Department of Analytical Chemistry, Faculty of Sciences, Marie Curie Annex Building, Campus of Rabanales, 14071 Córdoba, Spain.
J Chromatogr A. 2010 Sep 17;1217(38):5913-21. doi: 10.1016/j.chroma.2010.07.032. Epub 2010 Jul 21.
A new solvent extraction system was developed for extraction of PFCs from food. The extraction is carried out with 75:25 (v/v) tetrahydrofuran:water, a solvent mixture that provides an appropriate balance of hydrogen bonding, dispersion and dipole-dipole interactions to efficiently extract PFCs with chains containing 4-14 carbon atoms from foods. This mixture provided recoveries above 85% from foods including vegetables, fruits, fish, meat and bread; and above 75% from cheese. Clean-up with a weak anion exchange resin and Envi-carb SPE, which were coupled in line for simplicity, was found to minimize matrix effects (viz. enhancement or suppression of electrospray ionization). The target analytes (PFCs) were resolved on a perfluorooctyl phase column that proved effective in separating mass interferences for perfluorooctane sulfonate (PFOS) in fish and meat samples. The mass spectrometer was operated in the negative electrospray ionization mode and used to record two transitions per analyte and one per mass-labeled method internal standard. The target PFCs were quantified from solvent based calibration curves. The limits of detection (LODs) were as low as 1-5 pg analyte g(-1) food; by exception, those for C(4) and C(5) PFCs were somewhat higher (25-30 pg g(-1)) owing to their less favourable mass response. To the best of our knowledge these are among the best LODs for PFCs in foods reported to date. The analysis of a variety of foods revealed contamination with PFCs at levels from 4.5 to 75 pg g(-1) in 25% of samples (fish and packaged spinach). C(10)-C(14) PFCs were found in fish, which testifies to the need to control long-chain PFCs in this type of food. The proposed method is a useful tool for the development of a large-scale database for the presence of PFCs in foods.
建立了一种从食品中萃取全氟化合物(PFCs)的新型溶剂萃取体系。该萃取体系采用 75:25(v/v)四氢呋喃/水作为溶剂,这种溶剂混合物具有适当的氢键、分散和偶极-偶极相互作用平衡,可从包含 4-14 个碳原子的 PFC 链的食品中高效萃取 PFCs。该混合溶剂从蔬菜、水果、鱼、肉和面包等食品中获得了 85%以上的回收率;从奶酪中获得了 75%以上的回收率。通过简单在线耦合弱阴离子交换树脂和 Envi-carb SPE 进行净化,最大限度地减少了基质效应(即电喷雾电离的增强或抑制)。目标分析物(PFCs)在全氟辛基相柱上得到分离,该柱对鱼肉样品中全氟辛烷磺酸(PFOS)的质量干扰具有有效的分离效果。质谱仪采用负电喷雾电离模式运行,用于记录每个分析物两个跃迁和一个质量标记内标一个跃迁。目标 PFCs 从溶剂校准曲线中定量。检测限(LOD)低至 1-5 pg 分析物 g(-1) 食品;但例外的是,C(4)和 C(5) PFC 的 LOD 略高(25-30 pg g(-1)),这是由于它们的质量响应较差。据我们所知,这是迄今为止报道的食品中 PFC 检测限中较好的结果之一。对各种食品的分析表明,在 25%的样品(鱼和包装菠菜)中存在 PFC 污染,水平为 4.5 至 75 pg g(-1)。在鱼中发现了 C(10)-C(14) PFC,这证明需要控制这种食品中的长链 PFC。所提出的方法是建立食品中 PFC 存在情况的大型数据库的有用工具。