title: An advanced LC-MS (Q-TOF) technique for the detection of amino acids in atmospheric aerosols.
abstract: Methodology for detection of native (underivatized) amino acids (AA) in atmospheric aerosols has been developed. This article describes the use of LC-MS (Q-TOF) and microwave-assisted gas phase hydrolysis for detection of free and combined amino acids in aerosols collected in a Southeastern U.S. forest environment. Accurate mass detection and the addition of isotopically labeled surrogates prior to sample preparation allows for sensitive quantitation of target AA in a complex aerosol matrix. A total of 16 native AA were detected above the reporting threshold as water-soluble free AA, with an average concentration of 22 ± 9 ng m(-3) (N = 13). Following microwave-assisted gas phase hydrolysis, the total AA concentration in the forest environment increased significantly (70 ± 35 ng m(-3)) and additional compounds (methionine, isoleucine) were detected above the reporting threshold. The ability to quantify AA in aerosol samples without derivatization reduces time-consuming preparation procedures while providing the advancement of selective mass determination for important organic nitrogen (ON) species. Details on sample preparation that eliminates the freeze-drying approach typically practiced for water removal with biological samples, and vapor phase microwave hydrolysis parameters are provided. Method application for determination of atmospheric ON is discussed.
authors.affiliation: National Risk Management Research Laboratory (NRMRL), U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
authors.forename: Shar
authors.initials: S
authors.lastname: Samy
authors.forename: James
authors.initials: J
authors.lastname: Robinson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hays
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000388:Air / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*
chemical_list: D000336:Aerosols; D000596:Amino Acids