title: An anion-exchange high-performance liquid chromatography method coupled to total organic carbon determination for the analysis of water-soluble organic aerosols.
abstract: The chemical composition of water-soluble organic carbon (WSOC) in atmospheric aerosol particles is largely unexplored, due to the myriad of individual compounds, which has hampered attempts to attain a full characterization at the molecular level. An alternative approach, focusing on the analysis of a few main chemical classes, allowed the quantitative fractionation of WSOC into neutral compounds (NC), mono- and di-acids (MDA) and polyacids (PA) through an anion-exchange liquid chromatographic method. Previous attempts to quantify NC, MDA and PA relied on a low-pressure chromatographic technique using a volatile buffer, followed by total organic carbon (TOC) analysis of the fractions, or alternatively on a faster HPLC-UV method which provided a quantification of the fractions based on empirical relationships between UV signal and TOC concentration. Here, we report an upgraded anion-exchange HPLC technique, allowing direct TOC analysis of the eluted fractions, without any pre-treatment, thus permitting a great simplification of quantitative analysis and preventing sample losses. The new HPLC-TOC methodology, employing completely inorganic eluents shows the same efficiency of the former HPLC-UV method employing organic additives, with the exception of phenolic compounds, which are retained on the column by secondary interactions, and low-molecular weight tricarboxylic acids, which are recovered among MDA. The new anion-exchange liquid chromatographic method can recover a substantial amount (86-100%) of water-soluble organic carbon from atmospheric aerosol extracts, thus allowing a higher retention and fractionation capacity with respect to alternative techniques, like solid phase extraction.
authors.affiliation: Institute of Atmospheric Sciences and Climate, National Research Council, via Gobetti 101, 40129 Bologna, Italy.
authors.forename: Valeriana
authors.initials: V
authors.lastname: Mancinelli
authors.forename: Matteo
authors.initials: M
authors.lastname: Rinaldi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Finessi
authors.forename: Lorenza
authors.initials: L
authors.lastname: Emblico
authors.forename: Mihaela
authors.initials: M
authors.lastname: Mircea
authors.forename: Sandro
authors.initials: S
authors.lastname: Fuzzi
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Facchini
authors.forename: Stefano
authors.initials: S
authors.lastname: Decesari
mesh_terms: D000336:Aerosols; D000837:Anion Exchange Resins; D002244:Carbon / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D009930:Organic Chemicals / Q000032:analysis*; D012015:Reference Standards; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D014867:Water
chemical_list: D000336:Aerosols; D000837:Anion Exchange Resins; D009930:Organic Chemicals; D014867:Water; D002244:Carbon