Quantifying the impact of solid-phase extraction on chromophoric dissolved organic matter composition

Abstract

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Selective Adsorption of Terrestrial Dissolved Organic Matter to Inorganic Surfaces Along a Boreal Inland Water Continuum

“…Since long emission wavelength FDOM correlates with unsaturated compounds identified by mass spectrometry (Kellerman et al, ; Stubbins et al, ), both methods of investigating DOM composition show the same general pattern of selective adsorption of DOM with a terrestrial or allochthonous character. We recognize that both fluorescence and mass spectrometry capture only a fraction, and not necessarily a corresponding fraction (Hawkes et al, ; Wünsch et al, ), of the total DOM pool, as certain DOM fractions (nonfluorescent DOM and DOM molecules that are excluded in the various steps of the mass spectrometry method, e.g., SPE, ionization; Stubbins et al, ; Raeke et al, ) are not considered in these analyses. However, both methods have revealed meaningful patterns in DOM compositional data and are in agreement with regard to which types of compounds might be lost after exposure to the clay and which are unaffected.…”

Complexity of dissolved organic matter in the molecular size dimension: insights from coupled size exclusion chromatography electrospray ionisation mass spectrometry

“…The size range difference between optically active and ionisable DOM probably explains why solid phase extraction, which is poor at extracting high molecular weight components, 53,54 has a minimal effect on ESI-MS results, 54 but a large effect on absorption and uorescence spectroscopy. 55 Great care should therefore be taken in studies that aim to link the optical and MS character of terrestrial DOM [56][57][58][59][60] or the concentration of DOC and MS signal, 61 as the results being compared are not necessarily representing the same pools of carbon, 47,48,62 and relationships are likely to be coincidental, albeit related. This larger molecular weight pool, which we refer to as phenolic compounds (Fig.…”

Electrochemical characterization of natural organic matter by direct voltammetry in an aprotic solvent

“…The indeterminant composition of NOM is oen dealt with by (i) fractionation to decrease structural diversity and/or (ii) ngerprinting to encompass the whole range of NOM structural diversity. The various methods for fractionation of NOM have been optimized, standardized, compared, and criticized over many years of study, 7,[20][21][22][23][24] and during this process they have become deeply embedded in the literature on all aspects of NOM. The methods used to ngerprint NOM have expanded with advancements in the availability of high-resolution instrumentation, beginning with Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), 15,[25][26][27][28][29][30][31][32][33][34] then uorescence excitation emission matrices (EEMs), [35][36][37][38][39] and most recently Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS).…”

“…5,6,9,10,19,20,22,24,[40][41][42][43] The increasingly wholistic characterizations of NOM obtained from ngerprinting methods have renewed concerns over the representativeness of NOM samples obtained by extraction methods, 7,21,24 and growing recognition that sample preparation for ngerprinting can introduce biases due to fractionation. 19,20,[22][23][24]44 The ultimate motivation for on-going work on the characterization of NOM structure and composition is to enable new insights into its fate and effects. Currently, the main focus of this work is on the bioavailability of carbon in NOM, because of its role in the global carbon cycle, and implications for climate change.…”