title: How representative are dissolved organic matter (DOM) extracts? A comprehensive study of sorbent selectivity for DOM isolation.
abstract: Solid phase extraction (SPE) has become a widespread method for isolating dissolved organic matter (DOM) of diverse origin such as fresh and marine waters. This study investigated the DOM extraction selectivity of 24 commercially available SPE sorbents under identical conditions (pH = 2, methanol elution) on the example of Suwannee River (SR) water and North Sea (NS) water by using DOC analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to assess leaching behavior, and HLB sorbent was found to leach substantially, among others. Variable DOC recoveries observed for SR DOM and NS DOM were primarily caused by the respective molecular composition, with subordinated and heterogeneous contributions of relative salinity. Scatter of average H/C and O/C elemental ratios and gross alignment in mass-edited H/C ratios according to five established coarse SPE characteristics was near identical for SR DOM and NS DOM. FTMS-based principal component analysis (PCA) provided essentially analogous alignment of SR DOM and NS DOM molecular compositions according to the five established groups of SPE classification, and corroborated the sorption-mechanism-based selectivity of DOM extraction in both cases. Evaluation of structural blanks and leaching of SPE cartridges requires NMR spectroscopy because FT-ICR mass spectrometry alone will not reveal inconspicuous displacements of continual bulk signatures caused by leaching of SPE resin constituents.
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany; Chair of Analytical Food Chemistry, Technische Universität München, 85354 Freising, Germany.
authors.forename: Mourad
authors.initials: M
authors.lastname: Harir
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Jenny
authors.initials: J
authors.lastname: Uhl
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Basem
authors.initials: B
authors.lastname: Kanawati
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Marianna
authors.initials: M
authors.lastname: Lucio
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Kirill S
authors.initials: KS
authors.lastname: Smirnov
authors.affiliation: Alfred-Wegener-Institut, Helmholtz Zentrum für Polar- und Meeresforschung, Ecological Chemistry, Am Handelshafen 12, 27570 Bremerhaven, Germany; Hochschule Bremerhaven, University of Applied Sciences, An der Karlstadt 8, 27568 Bremerhaven, Germany.
authors.forename: Boris P
authors.initials: BP
authors.lastname: Koch
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany; Chair of Analytical Food Chemistry, Technische Universität München, 85354 Freising, Germany.
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitt-Kopplin
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany. Electronic address: hertkorn@helmholtz-muenchen.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Hertkorn
mesh_terms: D005618:Fresh Water / Q000737:chemistry*; D013058:Mass Spectrometry; D009659:North Sea; D052616:Solid Phase Extraction; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water
keywords: DOM; FT-ICR MS; Leaching; NMR; SPE; Sorbent selectivity