Department of Applied Environmental Science (ITM), Stockholm University, SE-10691 Stockholm, Sweden.
J Chromatogr A. 2011 Sep 16;1218(37):6388-95. doi: 10.1016/j.chroma.2011.07.005. Epub 2011 Jul 8.
A trace analytical method based on high performance liquid chromatography coupled to quadrupole time-of-flight high resolution mass spectrometry was developed for simultaneous determination of perfluoroalkyl phosphonates (PFPAs, carbon chain lengths C6,8,10), perfluoroalkyl carboxylates (PFCAs, C5-12), and perfluoroalkyl sulfonates (PFSAs, C4,6,8,10) in drinking water (tap water). Analytes were enriched on a mixed mode co-polymeric sorbent (C8+quaternary amine) using solid phase extraction. Chromatographic separation was achieved on a Zorbax Extend C18 reversed phase column using a mobile phase gradient consisting of water, methanol, and acetonitrile containing 2mM ammonium acetate and 5 mM 1-methyl piperidine. The mass spectrometer was operated in electrospray negative ion mode. Use of 1-methyl piperidine in the mobile phase resulted in a significant increase in instrument sensitivity for PFPAs through improved chromatographic resolution, background suppression, and increased ionization efficiency. Method detection limits for extraction of 500 mL tap water were in the ranges of 0.095-0.17 ng/L, 0.027-0.17 ng/L, and 0.014-0.052 ng/L for PFPAs, PFCAs, and PFSAs, respectively. Whole method recoveries at a spiking level of 0.5 ng/L to 500 mL HPLC grade water were 40-56%, 56-97%, and 55-77% for PFPAs, PFCAs, and PFSAs, respectively. A matrix effect (signal enhancement) was observed in the detection of PFPAs in tap water extracts, leading to calculated recoveries of 249-297% at a 0.5 ng/L spiking level. This effect resulted in an additional improvement of method sensitivity for PFPAs. To compensate for the matrix effect, PFPAs in tap water were quantified using matrix-matched and extracted calibration standards. The method was successfully applied to the analysis of drinking water collected from six European countries. PFPAs were not detected except for perfluorooctyl phosphonate (PFOPA) at close to the detection limit of 0.095 ng/L in two water samples from Amsterdam, the Netherlands. Highest levels were found for perfluorobutane sulfonate (PFBS, 18.8 ng/L) and perfluorooctanoate (PFOA, 8.6 ng/L) in samples from Amsterdam as well as for perfluorooctane sulfonate (PFOS, 8.8 ng/L) in tap water from Stockholm, Sweden.
建立了一种基于高效液相色谱-四极杆飞行时间高分辨质谱联用的痕量分析方法，用于同时测定饮用水（自来水）中的全氟烷基膦酸酯（PFPAs，碳链长度 C6、8、10）、全氟烷基羧酸（PFCAs，C5-12）和全氟烷基磺酸盐（PFSAs，C4、6、8、10）。采用混合模式共聚物（C8+季铵盐）在固相萃取上富集目标物。采用水、甲醇和乙腈作为流动相，流动相中含有 2mM 乙酸铵和 5mM1-甲基哌啶，在 Zorbax Extend C18 反相柱上实现色谱分离。质谱仪采用电喷雾负离子模式。在流动相中使用 1-甲基哌啶可提高 PFPAs 的仪器灵敏度，这是因为它改善了色谱分辨率、背景抑制和增加了离子化效率。对 500mL 自来水进行萃取，PFPAs、PFCAs 和 PFSAs 的方法检测限分别为 0.095-0.17ng/L、0.027-0.17ng/L 和 0.014-0.052ng/L。在 0.5ng/L 至 500mL HPLC 级水的加标水平下，PFPAs、PFCAs 和 PFSAs 的整体方法回收率分别为 40-56%、56-97%和 55-77%。在自来水中检测 PFPAs 时观察到基质效应（信号增强），导致在 0.5ng/L 加标水平下计算的回收率为 249-297%。该效应进一步提高了 PFPAs 的方法灵敏度。为了补偿基质效应，采用基质匹配和提取校准标准品对自来水中的 PFPAs 进行定量。该方法成功应用于来自六个欧洲国家的饮用水分析。除了在荷兰阿姆斯特丹的两个水样中接近检测限（0.095ng/L）检出的全氟辛基膦酸（PFOPA）外，其他水样中均未检出 PFPAs。在阿姆斯特丹的水样中，全氟丁烷磺酸（PFBS，18.8ng/L）和全氟辛酸（PFOA，8.6ng/L）以及瑞典斯德哥尔摩的自来水中的全氟辛烷磺酸（PFOS，8.8ng/L）的浓度最高。
