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Patriarca, C. (2018). Characterization of dissolved organic matter: An analytical challenge. (Licentiate dissertation). Uppsala: Department of Chemistry
Open this publication in new window or tab >>Characterization of dissolved organic matter: An analytical challenge
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Dissolved organic matter (DOM) is the prevalent form of organic carbon in most aquatic environments. It is an ultra-complex mixture that plays a crucial role in global carbon cycling. Despite its importance it is still poorly understood due to its extreme heterogeneity and intricacy. Major advances in chemical characterization of DOM were possible with the introduction of high-resolution mass spectrometry (HRMS). This technique, in combination with direct infusion (DI) as sample introduction, is the most powerful tool for the DOM analysis to date. A compelling alternative to DI is represented by upfront separation with liquid chromatography (LC); however, current techniques involve only offline LC-HRMS approaches, which exhibit important logistical drawbacks, making DOM analysis more challenging.

The aim of the presented studies was to develop new methods able to enhance the analysis of the dissolved organic matter and enable a wider range of researchers to participate in the advancement of this field.

In the first study, the application of the Orbitrap mass spectrometer for resolving complex DOM mixtures was investigated and the results were compared to the more established state-of-the-art technique, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The Orbitrap was capable of excellent reproducibility and detection of the majority of ionizable organic molecules in typical aquatic mixtures. The main disadvantage of the technique is that fewer molecular formulas can be resolved and detected because of lower resolution and sensitivity. This means that many sulfur peaks and all phosphorous containing peaks are not determined. Despite this drawback, our results suggest that the Orbitrap is an appropriate technique for the investigation of very subtle biogeochemical processing of bulk DOM. The lower costs (purchase and maintenance) and wider availability of Orbitrap mass spectrometers allow a greater number of laboratories to participate in the characterization of DOM.

In the second study, the first online method involving reverse phase chromatography and ultrahigh resolution mass spectrometry for the analysis of DOM was developed. This method overcomes the disadvantages of typical offline approaches. It enhances enormously the amount of information achievable in a single run, maintaining high resolution data, reducing analysis time and potential contamination. The introduction of in silico fractionation makes the method extremely flexible, allowing an easy, fast, and detailed comparison of DOM samples from a variety of sources.

Place, publisher, year, edition, pages
Uppsala: Department of Chemistry, 2018. p. 46
National Category
Analytical Chemistry
Research subject
Chemistry with specialization in Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-341690 (URN)
Presentation
2018-03-09, B7:101a, BMC, Husargatan 3, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2018-03-02 Created: 2018-02-12 Last updated: 2018-03-02Bibliographically approved
Hawkes, J. A., Patriarca, C., Sjöberg, P. J. R., Tranvik, L. & Bergquist, J. (2018). Extreme isomeric complexity of dissolved organic matter found across aquatic environments. Limnology and Oceanography Letters, 3(2), 21-30
Open this publication in new window or tab >>Extreme isomeric complexity of dissolved organic matter found across aquatic environments
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2018 (English)In: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 3, no 2, p. 21-30Article in journal (Refereed) Published
Abstract [en]

The natural aquatic environment contains an enormous pool of dissolved reduced carbon, present as ultra‐complex mixtures that are constituted by an unknown number of compounds at vanishingly small concentrations. We attempted to separate individual structural isomers from several samples using online reversed‐phase chromatography with selected ion monitoring/tandem mass spectrometry, but found that isomeric complexity still presented a boundary to investigation even after chromatographic simplification of the samples. However, it was possible to determine that the structural complexity differed among samples. Our results also suggest that extreme structural complexity was a ubiquitous feature of dissolved organic matter (DOM) in all aquatic systems, meaning that this diversity may play similar roles for recalcitrance and degradation of DOM in all tested environments.

National Category
Chemical Sciences Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-369282 (URN)10.1002/lol2.10064 (DOI)000456695800001 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Energy Agency
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2019-02-12Bibliographically approved
Patriarca, C., Bergquist, J., Sjöberg, P. J., Tranvik, L. & Hawkes, J. A. (2018). Online HPLC-ESI-HRMS Method for the Analysis and Comparison of Different Dissolved Organic Matter Samples. Environmental Science and Technology, 52(4), 2091-2099
Open this publication in new window or tab >>Online HPLC-ESI-HRMS Method for the Analysis and Comparison of Different Dissolved Organic Matter Samples
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2018 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 4, p. 2091-2099Article in journal (Refereed) Published
Abstract [en]

Natural dissolved organic matter (DOM) is an ultracomplex mixture that is essential to global carbon cycling but is poorly understood because of its complexity. The most powerful tool for the DOM characterization is high-resolution mass spectrometry (HRMS) generally combined to direct infusion (DI) as sample introduction. Liquid chromatography (LC) represents a compelling alternative to DI; however, state-of-the-art techniques involve only offline LC-HRMS approaches, which have important logistical drawbacks that make DOM analysis more challenging. This study introduces a new method based on online coupling of liquid chromatography to high resolution mass spectrometry, able to overcome the disadvantages of usual approaches. It is characterized by high reproducibility (% Bray–Curtis dissimilarity among replicates ≈ 2.5%), and it reduces transient complexity and contaminant interferences, thus increasing the signal-to-noise ratio (S/N), leading to the identification of an overall larger number of formulas in the mixture. Moreover, the application of an in silico fractionation prior to the statistical analysis allows an easy, flexible, fast, and detailed comparison of DOM samples from a variety of sources with a single chromatographic run.

National Category
Analytical Chemistry
Research subject
Chemistry with specialization in Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-341015 (URN)10.1021/acs.est.7b04508 (DOI)000426143300045 ()
Funder
Knut and Alice Wallenberg Foundation, 2013.0091Swedish Research Council, SRC 2015-4870Swedish Research Council, SRC 2014-04264
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-12-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4301-3923

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