Lashgari Maryam, Basheer Chanbasha, Kee Lee Hian
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Department of Chemistry, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia.
Talanta. 2015 Aug 15;141:200-6. doi: 10.1016/j.talanta.2015.03.049. Epub 2015 Apr 4.
In the present study, micro-solid phase extraction (µ-SPE) followed by liquid chromatography-triple tandem mass spectrometery (LC-MS/MS) was developed for the determination of perfluorocarboxylic acids (PFCAs) at trace levels in water samples. The µ-SPE device comprised of a porous polypropylene membrane bag containing 5mg sorbent. The membrane bag acted as a clean-up filter and prevented matrix compounds from interfering with the extraction process. Analysis was carried out by LC-MS/MS in negative electrospray ionization mode. MS/MS parameters were optimized for multiple reaction monitoring. Calcined and non-calcined MCM-41, as silica-ordered mesoporous materials, were used as sorbents in µ-SPE for the extraction of five PFCAs-perfluoropentanoic acid (PFPA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA)-from aqueous media. The performances of these two sorbents were compared with other sorbents such as octadecylsilane (C18) modified silica, HayeSep-A, HayeSep-B, and Porapak-R. It was found that non-calcined MCM-41 showed better extraction performance for the analytes considered. Parameters influencing extraction efficiency, such as desorption time, extraction time, desorption solvent, and salt concentration, were investigated. The effect of the matrix on MS signals (suppression or enhancement) was also evaluated. Only minor effects on ionization efficiencies were observed. The developed method proved to be convenient and offered good sensitivity and reproducibility. The limits of detection ranged from 0.02 to 0.08ng L(-1), with a relative standard deviations between 1.9 and 10.5. It was successfully applied to the extraction of PFCAs in river and rain water samples. As expected from the ubiquitous nature of PFCAs, contamination at low levels was detected for some analytes in the samples (with the highest concentration recorded for PFOA). Satisfactory relative recoveries ranging between 64% and 127% at spiking levels of 10ng L(-1) of each analyte were obtained.
在本研究中，开发了一种先进行微固相萃取（µ-SPE）再结合液相色谱-三重串联质谱（LC-MS/MS）的方法，用于测定水样中痕量的全氟羧酸（PFCA）。µ-SPE装置由一个装有5mg吸附剂的多孔聚丙烯膜袋组成。膜袋起到净化过滤器的作用，可防止基质化合物干扰萃取过程。分析通过LC-MS/MS在负电喷雾电离模式下进行。针对多反应监测对MS/MS参数进行了优化。煅烧和未煅烧的MCM-41作为二氧化硅有序介孔材料，被用作µ-SPE中的吸附剂，用于从水介质中萃取五种PFCA，即全氟戊酸（PFPA）、全氟庚酸（PFHpA）、全氟辛酸（PFOA）、全氟壬酸（PFNA）和全氟癸酸（PFDA）。将这两种吸附剂的性能与其他吸附剂进行了比较，如十八烷基硅烷（C18）改性硅胶、HayeSep-A、HayeSep-B和Porapak-R。结果发现，未煅烧的MCM-41对所考虑的分析物表现出更好的萃取性能。研究了影响萃取效率的参数，如解吸时间、萃取时间、解吸溶剂和盐浓度。还评估了基质对MS信号（抑制或增强）的影响。仅观察到对电离效率有轻微影响。所开发的方法证明是方便的，具有良好的灵敏度和重现性。检测限范围为0.02至0.08ng L⁻¹，相对标准偏差在1.9%至10.5%之间。该方法成功应用于河水和雨水样品中PFCA的萃取。正如PFCA普遍存在的性质所预期的那样，在样品中检测到了一些分析物的低水平污染（PFOA的浓度最高）。在每种分析物的加标水平为10ng L⁻¹时，获得了64%至127%的令人满意的相对回收率。
