title: Structural and compositional changes of dissolved organic matter upon solid-phase extraction tracked by multiple analytical tools.
abstract: Although PPL-based solid-phase extraction (SPE) has been widely used before dissolved organic matter (DOM) analyses via advanced measurements such as ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), much is still unknown about the structural and compositional changes in DOM pool through SPE. In this study, selected DOM from various sources were tested to elucidate the differences between before and after the SPE utilizing multiple analytical tools including fluorescence spectroscopy, FT-ICR-MS, and size exclusion chromatography with organic carbon detector (SEC-OCD). The changes of specific UV absorbance indicated the decrease of aromaticity after the SPE, suggesting a preferential exclusion of aromatic DOM structures, which was also confirmed by the substantial reduction of fluorescent DOM (FDOM). Furthermore, SEC-OCD results exhibited very low recoveries (1-9 %) for the biopolymer fraction, implying that PPL needs to be used cautiously in SPE sorbent materials for treating high molecular weight compounds (i.e., polysaccharides, proteins, and amino sugars). A careful examination via FT-ICR-MS revealed that the formulas lost by the SPE might be all DOM source-dependent. Nevertheless, the dominant missing compound groups were identified to be the tannins group with high O/C ratios (>0.7), lignins/carboxyl-rich alicyclic molecules (CRAM), aliphatics with high H/C >1.5, and heteroatomic formulas, all of which were prevailed by pseudo-analogous molecular formula families with different methylene (-CH2) units. Our findings shed new light on potential changes in the compound composition and the molecular weight of DOM upon the SPE, implying precautions needed for data interpretation. Graphical Abstract Tracking the characteristics of DOM from various origins upon PPL-based SPE utilizing EEMPARAFAC, SEC-OCD, and FT-ICR-MS.
authors.affiliation: Department of Environment & Energy, Sejong University, Gwangjin-gu, Seoul, 143-747, Republic of Korea.
authors.forename: Meilian
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Kyungpook National University, Daegu, 702-701, Republic of Korea.
authors.forename: Sunghwan
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Environment & Energy, Sejong University, Gwangjin-gu, Seoul, 143-747, Republic of Korea.|Research Group for Mass Spectrometry, Korea Basic Science Institute, Chungbuk, 363-883, Republic of Korea.
authors.forename: Jae-Eun
authors.initials: JE
authors.lastname: Park
authors.affiliation: Department of Environment & Energy, Sejong University, Gwangjin-gu, Seoul, 143-747, Republic of Korea.
authors.forename: Heon-Jae
authors.initials: HJ
authors.lastname: Jung
authors.affiliation: Department of Environment & Energy, Sejong University, Gwangjin-gu, Seoul, 143-747, Republic of Korea. jinhur@sejong.ac.kr.
authors.forename: Jin
authors.initials: J
authors.lastname: Hur
keywords: DOM sources; EEM-PARAFAC; FT-ICR-MS; Molecular weight; SEC-OCD; Solid-phase extraction