title: Determination of sugar compounds in atmospheric aerosols by liquid chromatography combined with positive electrospray ionization mass spectrometry.
abstract: We here report a method for the determination of sugar compounds of known presence in atmospheric aerosols using liquid chromatography (LC) combined with positive electrospray ionization mass spectrometry (MS). The target analytes include C(3)-C(6) monosaccharide alcohols (glycerol, erythritol, xylitol, mannitol), C(5)-C(6) monosaccharides (xylose, glucose, and levoglucosan), a disaccharide (sucrose), and a trisaccharide (melezitose). A mobile phase consisting of 20% 10 mM aqueous ammonium acetate, 8% methanol, and 72% water was found to provide abundant [M+NH(4)](+) adduct ions when coupled with electrospray ionization. Use of a polymer-based amino analytical column resolved the target compounds from the bulk solvent and provided limited separation among the target compounds. The target analytes were quantified using their [M+NH(4)](+) ions. Sample pretreatment was greatly simplified in comparison with the more commonly used gas chromatographic methods. It involved extraction of aerosol filters in methanol, evaporation of the solvent, and reconstitution with 5 mM ammonium acetate in water prior to the LC-MS analysis. The analyte recoveries were measured at the levels of 100, 500 and 1000 microg/L to be in the range of 78-102%, 94-112%, and 92-110%, respectively. The detection limits were lower than 10 pmol/injection for the tested target compounds except for xylose. Xylose had a detection limit of 95 pmol/injection. The method was applied to analyze 30 atmospheric aerosol samples to demonstrate its feasibility. The LC-MS method made possible the detection of trisaccharides as aerosol constituents for the first time.
authors.affiliation: Department of Chemistry, Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Eric Chun Hong
authors.initials: EC
authors.lastname: Wan
authors.forename: Jian Zhen
authors.initials: JZ
authors.lastname: Yu
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D001272:Atmosphere; D002241:Carbohydrates / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D000336:Aerosols; D002241:Carbohydrates