title: Quaternary ammonium-functionalized silica sorbents for the solid-phase extraction of aromatic amines under normal phase conditions.
abstract: Quaternary ammonium-functionalized silica materials were synthesized and applied for solid-phase extraction (SPE) of aromatic amines, which are classified as priority pollutants by US Environmental Protection Agency. Hexamethylenetetramine used for silica surface modification for the first time was employed as SPE sorbent under normal phase conditions. Hexaminium-functionalized silica demonstrated excellent extraction efficiencies for o-toluidine, 4-ethylaniline and quinoline (recoveries 101-107%), while for N,N-dimethylaniline and N-isopropylaniline recoveries were from low to moderate (14-46%). In addition, the suitability of 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica as SPE sorbent was tested under normal phase conditions. The recoveries achieved for the five aromatic amines ranged from 89 to 99%. The stability of the sorbent was evaluated during and after 150 extractions. Coefficients of variation between 4.5 and 10.2% proved a high stability of the synthesized sorbent. Elution was carried out using acetonitrile in the case of hexaminium-functionalized silica and water for 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent. After the extraction the analytes were separated and detected by liquid chromatography ultraviolet detection (LC-UV). The retention mechanism of the materials was primarily based on polar hydrogen bonding and π-π interactions. Comparison made with activated silica proved the quaternary ammonium-functionalized materials to offer different selectivity and better extraction efficiencies for aromatic amines. Finally, 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent was successfully tested for the extraction of wastewater and soil samples.
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, PO Box 55, University of Helsinki, FI-00014 Helsinki, Finland. lorena.vidal@ua.es
authors.forename: Lorena
authors.initials: L
authors.lastname: Vidal
authors.forename: Orlane
authors.initials: O
authors.lastname: Robin
authors.forename: Jevgeni
authors.initials: J
authors.lastname: Parshintsev
authors.forename: Jyri-Pekka
authors.initials: JP
authors.lastname: Mikkola
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Riekkola
mesh_terms: D000588:Amines / Q000032:analysis / Q000302:isolation & purification*; D002853:Chromatography, Liquid; D004355:Drug Stability; D004785:Environmental Pollutants / Q000032:analysis / Q000302:isolation & purification; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry; D008709:Methenamine / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D052616:Solid Phase Extraction / Q000295:instrumentation* / Q000379:methods; D062065:Wastewater / Q000737:chemistry
chemical_list: D000588:Amines; D004785:Environmental Pollutants; D007093:Imidazoles; D052578:Ionic Liquids; D008709:Methenamine; D000644:Quaternary Ammonium Compounds; D012822:Silicon Dioxide; D012987:Soil; D062065:Wastewater