Abstract

Purpose: Dissolved organic matter (DOM) composition is influenced by and modulates biogeochemical processes, yet DOM characterization techniques are challenged by its heterogeneous properties and structures. In this paper, ultrahigh electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is used to characterize previously isolated and well-characterized four DOM fractions from a water reservoir in the southwestern part of the USA. Materials and methods: About 50–60 L water samples were collected from Lake Pleasant (a water reservoir of Colorado River) and isolated and fractionated using a sequential isolation and fractionation procedure. DOM was firstly fractionated to the colloids and soluble permeate, then hydrophobic acids (HPO-A) and neutrals (HPO-N) plus amphiphilic acids (AMP-A) and neutrals (AMP-N) were fractionated using the resin-in-tandem procedure. Approximately 0.7 mg sample was dissolved in 250 μL methanol/water mixture (1:1, v/v) and diluted twice with 0.1 % (by volume) NH4OH (in 1:1 methanol/water, v/v) and measured by ESI-FTICR in negative ion mode. Results and discussion: In the m/z range of <700, among the sum of 4107 peaks, HPO-N contained the most assigned 1763 molecules and HPO-A, AMP-N, and AMP-A contained 971, 990, and 293, respectively. Acid fractions were relatively more oxygenated than the corresponding neutrals. Except for the major assigned CHO molecules, a high portion of heteroatom-containing molecules were assigned in the neutral fractions. Van Krevelen and Venn diagrams analyses showed significant molecular differentiation among the fractions. Among the assigned formulas, the Venn diagram indicated only a small portion (<4 %) of distinct formulas overlapped. S-containing molecules were efficiently ionized and identified in the neutrals. Some of the S1-containing compounds with high signal magnitudes are tentatively assigned to alkylbenzene sulfonates and their biodegradation and biotransformation derivatives indicating anthropogenic input on site. Conclusions: By using the XAD resin-in-tandem approach and FTICR-MS, numbers of DOM molecules in fractions were distinctly separated, accordingly the complexity of DOM was reduced. Furthermore, to a great extent, the compositions and structures of each fraction in the molecular level are remarkably different as evidenced by only small portion of molecules overlapping.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalJournal of Soils and Sediments
DOIs
StateAccepted/In press - Oct 25 2016

Fingerprint

dissolved organic matter
Fourier transform
mass spectrometry
ion
acid
methanol
resin
ionization
diagram
sulfonate
biotransformation
colloid
water
water reservoir
comparison
biodegradation
fractionation
lake
river

Keywords

  • Amphiphilic
  • DOM
  • ESI
  • FTICR-MS
  • Hydrophobic

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Stratigraphy

Cite this

Comparison of hydrophobic and amphiphilic fractions of dissolved organic matter from a water reservoir by Fourier transform ion cyclotron resonance mass spectrometry. / Song, Guixue; Mesfioui, Rajaa; Dotson, Aaron; Westerhoff, Paul; Hatcher, Patrick.

In: Journal of Soils and Sediments, 25.10.2016, p. 1-14.

Research output: Contribution to journalArticle

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abstract = "Purpose: Dissolved organic matter (DOM) composition is influenced by and modulates biogeochemical processes, yet DOM characterization techniques are challenged by its heterogeneous properties and structures. In this paper, ultrahigh electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is used to characterize previously isolated and well-characterized four DOM fractions from a water reservoir in the southwestern part of the USA. Materials and methods: About 50–60 L water samples were collected from Lake Pleasant (a water reservoir of Colorado River) and isolated and fractionated using a sequential isolation and fractionation procedure. DOM was firstly fractionated to the colloids and soluble permeate, then hydrophobic acids (HPO-A) and neutrals (HPO-N) plus amphiphilic acids (AMP-A) and neutrals (AMP-N) were fractionated using the resin-in-tandem procedure. Approximately 0.7 mg sample was dissolved in 250 μL methanol/water mixture (1:1, v/v) and diluted twice with 0.1 {\%} (by volume) NH4OH (in 1:1 methanol/water, v/v) and measured by ESI-FTICR in negative ion mode. Results and discussion: In the m/z range of <700, among the sum of 4107 peaks, HPO-N contained the most assigned 1763 molecules and HPO-A, AMP-N, and AMP-A contained 971, 990, and 293, respectively. Acid fractions were relatively more oxygenated than the corresponding neutrals. Except for the major assigned CHO molecules, a high portion of heteroatom-containing molecules were assigned in the neutral fractions. Van Krevelen and Venn diagrams analyses showed significant molecular differentiation among the fractions. Among the assigned formulas, the Venn diagram indicated only a small portion (<4 {\%}) of distinct formulas overlapped. S-containing molecules were efficiently ionized and identified in the neutrals. Some of the S1-containing compounds with high signal magnitudes are tentatively assigned to alkylbenzene sulfonates and their biodegradation and biotransformation derivatives indicating anthropogenic input on site. Conclusions: By using the XAD resin-in-tandem approach and FTICR-MS, numbers of DOM molecules in fractions were distinctly separated, accordingly the complexity of DOM was reduced. Furthermore, to a great extent, the compositions and structures of each fraction in the molecular level are remarkably different as evidenced by only small portion of molecules overlapping.",
keywords = "Amphiphilic, DOM, ESI, FTICR-MS, Hydrophobic",
author = "Guixue Song and Rajaa Mesfioui and Aaron Dotson and Paul Westerhoff and Patrick Hatcher",
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T1 - Comparison of hydrophobic and amphiphilic fractions of dissolved organic matter from a water reservoir by Fourier transform ion cyclotron resonance mass spectrometry

AU - Song, Guixue

AU - Mesfioui, Rajaa

AU - Dotson, Aaron

AU - Westerhoff, Paul

AU - Hatcher, Patrick

PY - 2016/10/25

Y1 - 2016/10/25

N2 - Purpose: Dissolved organic matter (DOM) composition is influenced by and modulates biogeochemical processes, yet DOM characterization techniques are challenged by its heterogeneous properties and structures. In this paper, ultrahigh electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is used to characterize previously isolated and well-characterized four DOM fractions from a water reservoir in the southwestern part of the USA. Materials and methods: About 50–60 L water samples were collected from Lake Pleasant (a water reservoir of Colorado River) and isolated and fractionated using a sequential isolation and fractionation procedure. DOM was firstly fractionated to the colloids and soluble permeate, then hydrophobic acids (HPO-A) and neutrals (HPO-N) plus amphiphilic acids (AMP-A) and neutrals (AMP-N) were fractionated using the resin-in-tandem procedure. Approximately 0.7 mg sample was dissolved in 250 μL methanol/water mixture (1:1, v/v) and diluted twice with 0.1 % (by volume) NH4OH (in 1:1 methanol/water, v/v) and measured by ESI-FTICR in negative ion mode. Results and discussion: In the m/z range of <700, among the sum of 4107 peaks, HPO-N contained the most assigned 1763 molecules and HPO-A, AMP-N, and AMP-A contained 971, 990, and 293, respectively. Acid fractions were relatively more oxygenated than the corresponding neutrals. Except for the major assigned CHO molecules, a high portion of heteroatom-containing molecules were assigned in the neutral fractions. Van Krevelen and Venn diagrams analyses showed significant molecular differentiation among the fractions. Among the assigned formulas, the Venn diagram indicated only a small portion (<4 %) of distinct formulas overlapped. S-containing molecules were efficiently ionized and identified in the neutrals. Some of the S1-containing compounds with high signal magnitudes are tentatively assigned to alkylbenzene sulfonates and their biodegradation and biotransformation derivatives indicating anthropogenic input on site. Conclusions: By using the XAD resin-in-tandem approach and FTICR-MS, numbers of DOM molecules in fractions were distinctly separated, accordingly the complexity of DOM was reduced. Furthermore, to a great extent, the compositions and structures of each fraction in the molecular level are remarkably different as evidenced by only small portion of molecules overlapping.

AB - Purpose: Dissolved organic matter (DOM) composition is influenced by and modulates biogeochemical processes, yet DOM characterization techniques are challenged by its heterogeneous properties and structures. In this paper, ultrahigh electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is used to characterize previously isolated and well-characterized four DOM fractions from a water reservoir in the southwestern part of the USA. Materials and methods: About 50–60 L water samples were collected from Lake Pleasant (a water reservoir of Colorado River) and isolated and fractionated using a sequential isolation and fractionation procedure. DOM was firstly fractionated to the colloids and soluble permeate, then hydrophobic acids (HPO-A) and neutrals (HPO-N) plus amphiphilic acids (AMP-A) and neutrals (AMP-N) were fractionated using the resin-in-tandem procedure. Approximately 0.7 mg sample was dissolved in 250 μL methanol/water mixture (1:1, v/v) and diluted twice with 0.1 % (by volume) NH4OH (in 1:1 methanol/water, v/v) and measured by ESI-FTICR in negative ion mode. Results and discussion: In the m/z range of <700, among the sum of 4107 peaks, HPO-N contained the most assigned 1763 molecules and HPO-A, AMP-N, and AMP-A contained 971, 990, and 293, respectively. Acid fractions were relatively more oxygenated than the corresponding neutrals. Except for the major assigned CHO molecules, a high portion of heteroatom-containing molecules were assigned in the neutral fractions. Van Krevelen and Venn diagrams analyses showed significant molecular differentiation among the fractions. Among the assigned formulas, the Venn diagram indicated only a small portion (<4 %) of distinct formulas overlapped. S-containing molecules were efficiently ionized and identified in the neutrals. Some of the S1-containing compounds with high signal magnitudes are tentatively assigned to alkylbenzene sulfonates and their biodegradation and biotransformation derivatives indicating anthropogenic input on site. Conclusions: By using the XAD resin-in-tandem approach and FTICR-MS, numbers of DOM molecules in fractions were distinctly separated, accordingly the complexity of DOM was reduced. Furthermore, to a great extent, the compositions and structures of each fraction in the molecular level are remarkably different as evidenced by only small portion of molecules overlapping.

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KW - ESI

KW - FTICR-MS

KW - Hydrophobic

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