Molecular Level Analysis Reveals Changes in Chemical Composition of Dissolved Organic Matter From South Texas Rivers After High Flow Events

Lu, Kaijun; Liu, Zhanfei

doi:10.3389/fmars.2019.00673

Cited by 24 publications

(26 citation statements)

References 88 publications

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“…Any feature detected in the 14 N‐Phe incubation that had a counterpart with a matched LC retention time, but a higher molecular mass equal to an integer multiple of 0.9970 (the mass difference between 15 N and 14 N) in the 15 N‐Phe incubation, was determined as an N‐containing molecule originated from the degradation of Phe (hereinafter Phe‐DON; Text S4 in Supporting Information ). A preferred ID list was created based on the detected features and applied in the subsequent data‐dependent tandem MS (MS/MS) analysis under ESI + mode (K. Lu & Liu, 2019; K. Lu et al., 2018, 2021). This is the first time that stable isotope labeling in combination with high resolution mass spectrometry is applied to investigate the formation of natural organic matter in aquatic systems (Kolkman et al., 2015; Z. Liu et al., 2019; Tian et al., 2018; Y. Lu, Wang, et al., 2021).…”

Section: Methodsmentioning

confidence: 99%

The Formation of Refractory Dissolved Organic Nitrogen From Free Amino Acids in the Ocean

Liu

2022

Geophysical Research Letters

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Dissolved organic nitrogen (DON) is actively involved in N cycling and transformation processes in the ocean, yet how this large N pool is formed remains elusive. Here we incubated 15N‐labeled individual amino acids (Ala, Val, and Phe) in seawater and monitored their fates over 21 days. About 25%–45% of Phe‐N and Val‐N were transformed to “uncharacterizable DON,” as compared to only about 6% for Ala‐N, indicating the formation of refractory DON is related to specific amino acids. Through a stable isotope probing approach, 5 Phe‐derived DON molecules from the incubations were found to be present in natural waters, and their possible structures were proposed. These results shed new lights on the formation mechanisms of refractory DON, including the roles of specific amino acids and particular chemical structures that may resist decomposition in millennial time scales.

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Section: Methodsmentioning

confidence: 99%

The Formation of Refractory Dissolved Organic Nitrogen From Free Amino Acids in the Ocean

Liu

2022

Geophysical Research Letters

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“…b An HPLC–MS/MS scan of isomeric mixture peaks from Nordic Reservoir natural organic matter (NRNOM) reference material, depicting the inability to distinguish fragmentation patterns from individual isomers from a molecular mass (adapted from Hawkes et al 2018 ). c An example of an assigned structure (C22H18O12) based on a riverine DOM MS/MS spectra and the METLIN database (adapted from Lu and Liu 2019 ). d The structural units identified by multidimensional nuclear magnetic resonance (NMR), in which each dot represents one structural feature (Hertkorn et al 2012 ) …”

Section: Molecular Characterization Of Marine Dom and Chemometricsmentioning

confidence: 99%

Marine dissolved organic matter: a vast and unexplored molecular space

Catalá

Shorte

Dittmar

2021

Appl Microbiol Biotechnol

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Marine dissolved organic matter (DOM) comprises a vast and unexplored molecular space. Most of it resided in the oceans for thousands of years. It is among the most diverse molecular mixtures known, consisting of millions of individual compounds. More than 1 Eg of this material exists on the planet. As such, it comprises a formidable source of natural products promising significant potential for new biotechnological purposes. Great emphasis has been placed on understanding the role of DOM in biogeochemical cycles and climate attenuation, its lifespan, interaction with microorganisms, as well as its molecular composition. Yet, probing DOM bioactivities is in its infancy, largely because it is technically challenging due to the chemical complexity of the material. It is of considerable interest to develop technologies capable to better discern DOM bioactivities. Modern screening technologies are opening new avenues allowing accelerated identification of bioactivities for small molecules from natural products. These methods diminish a priori the need for laborious chemical fractionation. We examine here the application of untargeted metabolomics and multiplexed high-throughput molecular-phenotypic screening techniques that are providing first insights on previously undetectable DOM bioactivities. Key points • Marine DOM is a vast, unexplored biotechnological resource. • Untargeted bioscreening approaches are emerging for natural product screening. • Perspectives for developing bioscreening platforms for marine DOM are discussed.

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“…Thus, a thorough knowledge of DOM chemical composition and structure at the molecular level is essential for the understanding of its role in the aquatic environments. Although the molecular features of DOM have been the focus of a multitude of studies over the last decades, − the elucidation of its chemical structure and a clear view of DOM isomeric complexity persist as one of the most challenging analytical problems. − …”

Section: Introductionmentioning

confidence: 99%

“…Analytical approaches integrating ultrahigh-resolution mass spectrometry, gas/liquid preseparation techniques, and tandem mass spectrometry strategies have provided much of the existing information on the chemical diversity of DOM. ,− An online HPLC-Orbitrap MS/MS method developed by Hawkes et al was used in an attempt to isolate single compounds in DOM samples from different ecosystems. Although the ubiquitous nature of DOM isomeric complexity was demonstrated, the proposed procedure was unable to separate individual compounds and differentiate fragmentation patterns from specific isomers of the same chemical formula.…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization of Dissolved Organic Matter at the Chemical Formula Level Using TIMS-FT-ICR MS/MS

2020

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TIMS-FT-ICR MS is an important alternative to study the isomeric diversity and elemental composition of complex mixtures. While the chemical structure of many compounds in the dissolved organic matter (DOM) remains largely unknown, the high structural diversity has been described at the molecular level using chemical formulas. In this study, we further push the boundaries of TIMS-FT-ICR MS by performing chemical formula-based ion mobility and tandem MS analysis for the structural characterization of DOM. The workflow described is capable to mobility select (R ∼ 100) and isolate molecular ion signals (Δm/z = 0.036) in the ICR cell, using single-shot ejections after broadband ejections and MS/MS based on sustained off-resonance irradiation collision-induced dissociation (SORI-CID). The workflow results are compared to alternative TIMS-q-FT-ICR MS/MS experiments with quadrupole isolation at nominal mass (∼1 Da). The technology is demonstrated with isomeric and isobaric mixtures (e.g., 4-methoxy-1-naphthoic acid, 2-methoxy-1-naphthoic acid, decanedioic acid) and applied to the characterization of DOM. The application of this new methodology to the analysis of a DOM is illustrated by the isolation of the molecular ion [C18H18O10-H]− in the presence of other isobars at nominal mass 393. Five IMS bands were assigned to the heterogeneous ion mobility profile of [C18H18O10-H]−, and candidate structures from the PubChem database were screened based on their ion mobility and the MS/MS matching score. This approach overcomes traditional challenges associated with the similarity of fragmentation patterns of DOM samples (e.g., common neutral losses of H2O, CO2, and CH2–H2O) by narrowing down the isomeric candidate structures using the mobility domain.

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Molecular Level Analysis Reveals Changes in Chemical Composition of Dissolved Organic Matter From South Texas Rivers After High Flow Events

Cited by 24 publications

References 88 publications

The Formation of Refractory Dissolved Organic Nitrogen From Free Amino Acids in the Ocean

The Formation of Refractory Dissolved Organic Nitrogen From Free Amino Acids in the Ocean

Marine dissolved organic matter: a vast and unexplored molecular space

Structural Characterization of Dissolved Organic Matter at the Chemical Formula Level Using TIMS-FT-ICR MS/MS

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