title: Proton sponge-functionalized silica as high performance adsorbents for solid-phase extraction of trace perfluoroalkyl sulfonates in the environmental water samples and their direct analysis by MALDI-TOF-MS.
abstract: 1,8-Bis(dimethylamino)naphthalene (DMAN), a classical 'proton sponge', was functionalized on silica particles as a novel solid-phase extraction (SPE) adsorbent (DMAN@silica) for extracting perfluoroalkyl sulfonates (PFSs). High reproducibility and excellent extraction capability for PFSs were obtained in a wide pH range (3.0~8.5). The adsorbed PFSs on DMAN@silica sorbents could be efficiently eluted by 1,8-bis(tetramethylguanidino)naphthalene (TMGN) solution which is a proton sponge with higher proton affinity than DMAN. The elution could be directly analyzed by MALDI-TOF-MS using TMGN as matrix. Clear mass spectra for the PFSs were obtained due to no matrix ions interference observed. Furthermore, a novel strategy based on the DMAN@silica-SPE enrichment, followed by MALDI-TOF-MS analysis, was proposed and applied for PFSs quantification in environmental water samples. The calibration curves of each of the target analytes showed a wide linear dynamic range of response (0.1-10 ng L(-1) for perfluorooctane sulfonate (PFOS), perfluorohexyl sulfonate (PFHxS) and perfluorobutylsulfonate (PFBS)), which were over 2 orders of magnitude. The detection limits for PFOS, PFHxS, and PFBS were 0.021, 0.016, and 0.013 ng L(-1), respectively (S/N = 3). Recoveries of PFOS, PFHxS, and PFBS are in the ranges of 92-104%, 95-102%, and 98-109% for spiked river water samples. These results indicated that the prepared DMAN@silica adsorbents could efficiently enrich PFSs and that the proposed method is reliable.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Haidian district, Beijing 100085, People's Republic of China.
authors.forename: Dong
authors.initials: D
authors.lastname: Cao
authors.forename: Ming
authors.initials: M
authors.lastname: Hu
authors.forename: Chunguang
authors.initials: C
authors.lastname: Han
authors.forename: Jiyao
authors.initials: J
authors.lastname: Yu
authors.forename: Lin
authors.initials: L
authors.lastname: Cui
authors.forename: Yongxue
authors.initials: Y
authors.lastname: Liu
authors.forename: Hailin
authors.initials: H
authors.lastname: Wang
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Cai
authors.forename: Yuehui
authors.initials: Y
authors.lastname: Kang
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D000327:Adsorption; D004777:Environment; D006863:Hydrogen-Ion Concentration; D011522:Protons; D012822:Silicon Dioxide / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013451:Sulfonic Acids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D014867:Water / Q000737:chemistry*
chemical_list: D011522:Protons; D013451:Sulfonic Acids; D014867:Water; C418992:1,8-bis(dimethylamino)naphthalene; D012822:Silicon Dioxide; D015057:1-Naphthylamine