The Experts below are selected from a list of 1032 Experts worldwide ranked by ideXlab platform
Patrick G Hatcher - One of the best experts on this subject based on the ideXlab platform.
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Chemical compositional analysis of soil fulvic acids using Fourier transform ion cyclotron resonance mass spectrometry.
Rapid communications in mass spectrometry : RCM, 2020Co-Authors: Kosuke Ikeya, Patrick G Hatcher, Rachel L. Sleighter, Akira WatanabeAbstract:Rationale Soil fulvic acids (FAs) are considered to be a highly reactive pool of soil organic matter. The functions of FAs are related to their chemical structures, the details of which are largely unidentified. To better understand them, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) must be a useful but generally unused tool. Methods The structural properties of the components of five FA samples from a variety of soils were determined using FTICR-MS with negative-mode electrospray ionization. The peaks were assigned to molecular formulae, which were categorized into seven compound groups based on the H/C-O/C Van Krevelen Diagram. Ramp 13 C cross polarization/magic angle spinning nuclear magnetic resonance (NMR) spectra with phase-adjusted spinning side bands were also recorded to estimate the C composition. Results From FTICR-MS, molecular formulae were assigned to 1746-2605 peaks across the m/z range of 200-700. Those aligned in the lignin-like, tannin-like, and condensed aromatic regions of the Van Krevelen Diagram accounted for 49-58%, 4-20%, and 18-39% of the total peak magnitude, respectively. The proportion of the summed peak magnitudes that were detected in the lignin-like and condensed aromatic regions correlated positively to the aromatic C% as estimated by 13 C NMR. From Kendrick mass defect analysis using a carboxyl group, 94 molecular formulae were assigned to condensed aromatic acids, of which the maximum ring number was 4-7, as potential structures. Conclusions A high proportion of lignin-like formulae and condensed aromatics, including those probably condensed aromatic acids with small ring numbers, as well as the existence of tannin-like formulae, which were generally lacking in soil humic acids, was suggested as a common feature of soil FAs.
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Two Dimensional Correlation Analysis of Fourier Transform Ion Cyclotron Resonance Mass Spectra of Dissolved Organic Matter: A New Graphical Analysis of Trends
Analytical chemistry, 2013Co-Authors: Hussain A.n. Abdulla, Rachel L. Sleighter, Patrick G HatcherAbstract:Two-dimensional (2D) correlation analysis was applied to 20 Fourier transform ion cyclotron resonance mass spectra (FTICR-MS) of ultrafiltered dissolved organic matter samples from a salinity transect of the lower Chesapeake Bay. We were able to investigate the chemical changes in the dissolved organic matter pool at the molecular level and classify the individual peaks based on their biogeochemical reactivity. The power of this technique is its ability to be used on either the presence/absence of the individual peaks or their normalized magnitudes. The presence or absence of the peaks are utilized to identify the reactivity and correlation between peaks that plot in different regions of the Van Krevelen Diagram, whereas the normalized magnitudes are used to correlate the changes among individual peaks. One of the promising adVantages of 2D correlation of FTICR-MS data is the ability to associate the variations of the individual peaks with the changes in the functional groups that are measured by other sp...
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multivariate statistical approaches for the characterization of dissolved organic matter analyzed by ultrahigh resolution mass spectrometry
Environmental Science & Technology, 2010Co-Authors: Rachel L. Sleighter, Patrick G HatcherAbstract:We apply multivariate statistics to explore the large data sets encountered from Fourier transform ion cyclotron resonance mass spectra of dissolved organic matter (DOM). Molecular formula assignments for the individual constituents of DOM are examined by hierarchal cluster analysis (HCA) and principal component analysis (PCA), to measure the relationships between numerous DOM samples. We compare two approaches: (1) using averages of elemental ratios and double bond equivalents calculated from the formulas, and (2) employing individual formulas and either their presence/absence or relative magnitude in each sample. With approach 2, PCA deciphers which of the thousands of formulas are significant to particular samples, and then a Van Krevelen Diagram highlights what types of compounds are molecular signatures to the samples. Our dual approach, especially approach 2, allows for complex data sets to be more easily interpreted, aiding in the characterization of DOM from various sources. By applying this metho...
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graphical method for analysis of ultrahigh resolution broadband mass spectra of natural organic matter the Van Krevelen Diagram
Analytical Chemistry, 2003Co-Authors: And Robert W Kramer, Patrick G HatcherAbstract:Electrospray ionization mass spectrometry (ESI-MS) is becoming an important tool in the study of natural organic matter (NOM) at the molecular level.1 Ultrahigh-resolution ESI-MS analyses of NOM often produce very complicated spectra; therefore, visual presentation and structural interpretations of the spectra are difficult. To meet this analytical challenge, we herein propose and demonstrate an approach using the Van Krevelen Diagram. With this approach, complicated mass spectra can be visualized in a way that allows for (1) possible reaction pathways to be identified and presented, and (2) qualitative analyses on major classes of compounds that comprise ultrahigh-resolution spectra. The qualitative analyses are in a good agreement with results obtained from analyses by other analytical techniques. Additionally, the Van Krevelen Diagram can be expanded to a 3D plot by using peak intensities or relative intensities as the z-axis. The 3D Van Krevelen Diagram allows for an evaluation of the relative signifi...
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artificial coalification of a fossil wood from brown coal by confined system pyrolysis
Energy & Fuels, 1995Co-Authors: Francoise Behar, Patrick G HatcherAbstract:Artificial coalification of a sample of fossil wood of lignitic rank by a confined system pyrolysis in gold tubes reveals that such a simulation only partially mimics natural coalification processes. Analysis of gaseous products by gas chromatography, liquid products by gas chromatography/mass spectrometry, and solid products by elemental analysis, quantitative solid-state 13 C NMR, and flash pyrolysis/gas chromatography/mass spectrometry allows mass balance calculations. It is clear that, for this sample, confined system pyrolysis reproduces well the natural transformations of aromatic rings, but the reactions of aliphatic structures, derived predominantly from the side-chain carbons of lignin, are not simulated by such an artificial maturation process. This partially explains the deviations from the normal Van Krevelen Diagram observed in most artificial maturation experiments. The primary gaseous product, CO 2 , appears to originate from carboxyl and carbonyl groups and the methane, generated during the most severe stages of thermal treatment, appears to derive from methyl substituents on aromatic rings. The main liquid products observed are phenols, alkylbenzenes, and naphthalenes, with the phenolic products predominating at low severity and the naphthalenes and alkylbenzenes at high severity.
Maria João Cabrita - One of the best experts on this subject based on the ideXlab platform.
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Revisiting 3D Van Krevelen Diagrams as a tool for the visualization of volatile profile of varietal olive oils from Alentejo region, Portugal.
Talanta, 2019Co-Authors: Nuno Martins, Nicasio T. Jiménez-morillo, Flavia Freitas, Raquel Garcia, Marco Silva, Maria João CabritaAbstract:This paper aims to study the volatile composition of monovarietal extra-virgin olive oils from different varieties from Alentejo region (Portugal). Volatile profile of 82 olive oils was performed by head-space solid phase micro-extraction hyphenated with gas chromatography/mass spectrometry (HS-SPME-GC/MS). A total of 107 volatile compounds, belonging to several class of compounds, like aldehydes, hydrocarbons, alcohols, terpenoids, ketones, sulphurous compounds, acids and esters were identified, assigned to a specific biogenic origin and total abundances were plotted in modified 3D Van Krevelen Diagrams. The 3D plots showed that there are compositional differences among olive oil varieties. Discriminant analysis confirmed that the pattern of volatile compounds includes enough information to group sample variety amongst discrete monovarietal olive oil. Combining statistical analysis (t-Student) and graphical-tools (Van Krevelen Diagram) seems to be a powerful tool to determine what molecular families were characteristic of each olive oil variety, contributing to the valorization of monovarietal Portuguese olive oil.
Rachel L. Sleighter - One of the best experts on this subject based on the ideXlab platform.
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Chemical compositional analysis of soil fulvic acids using Fourier transform ion cyclotron resonance mass spectrometry.
Rapid communications in mass spectrometry : RCM, 2020Co-Authors: Kosuke Ikeya, Patrick G Hatcher, Rachel L. Sleighter, Akira WatanabeAbstract:Rationale Soil fulvic acids (FAs) are considered to be a highly reactive pool of soil organic matter. The functions of FAs are related to their chemical structures, the details of which are largely unidentified. To better understand them, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) must be a useful but generally unused tool. Methods The structural properties of the components of five FA samples from a variety of soils were determined using FTICR-MS with negative-mode electrospray ionization. The peaks were assigned to molecular formulae, which were categorized into seven compound groups based on the H/C-O/C Van Krevelen Diagram. Ramp 13 C cross polarization/magic angle spinning nuclear magnetic resonance (NMR) spectra with phase-adjusted spinning side bands were also recorded to estimate the C composition. Results From FTICR-MS, molecular formulae were assigned to 1746-2605 peaks across the m/z range of 200-700. Those aligned in the lignin-like, tannin-like, and condensed aromatic regions of the Van Krevelen Diagram accounted for 49-58%, 4-20%, and 18-39% of the total peak magnitude, respectively. The proportion of the summed peak magnitudes that were detected in the lignin-like and condensed aromatic regions correlated positively to the aromatic C% as estimated by 13 C NMR. From Kendrick mass defect analysis using a carboxyl group, 94 molecular formulae were assigned to condensed aromatic acids, of which the maximum ring number was 4-7, as potential structures. Conclusions A high proportion of lignin-like formulae and condensed aromatics, including those probably condensed aromatic acids with small ring numbers, as well as the existence of tannin-like formulae, which were generally lacking in soil humic acids, was suggested as a common feature of soil FAs.
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Two Dimensional Correlation Analysis of Fourier Transform Ion Cyclotron Resonance Mass Spectra of Dissolved Organic Matter: A New Graphical Analysis of Trends
Analytical chemistry, 2013Co-Authors: Hussain A.n. Abdulla, Rachel L. Sleighter, Patrick G HatcherAbstract:Two-dimensional (2D) correlation analysis was applied to 20 Fourier transform ion cyclotron resonance mass spectra (FTICR-MS) of ultrafiltered dissolved organic matter samples from a salinity transect of the lower Chesapeake Bay. We were able to investigate the chemical changes in the dissolved organic matter pool at the molecular level and classify the individual peaks based on their biogeochemical reactivity. The power of this technique is its ability to be used on either the presence/absence of the individual peaks or their normalized magnitudes. The presence or absence of the peaks are utilized to identify the reactivity and correlation between peaks that plot in different regions of the Van Krevelen Diagram, whereas the normalized magnitudes are used to correlate the changes among individual peaks. One of the promising adVantages of 2D correlation of FTICR-MS data is the ability to associate the variations of the individual peaks with the changes in the functional groups that are measured by other sp...
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multivariate statistical approaches for the characterization of dissolved organic matter analyzed by ultrahigh resolution mass spectrometry
Environmental Science & Technology, 2010Co-Authors: Rachel L. Sleighter, Patrick G HatcherAbstract:We apply multivariate statistics to explore the large data sets encountered from Fourier transform ion cyclotron resonance mass spectra of dissolved organic matter (DOM). Molecular formula assignments for the individual constituents of DOM are examined by hierarchal cluster analysis (HCA) and principal component analysis (PCA), to measure the relationships between numerous DOM samples. We compare two approaches: (1) using averages of elemental ratios and double bond equivalents calculated from the formulas, and (2) employing individual formulas and either their presence/absence or relative magnitude in each sample. With approach 2, PCA deciphers which of the thousands of formulas are significant to particular samples, and then a Van Krevelen Diagram highlights what types of compounds are molecular signatures to the samples. Our dual approach, especially approach 2, allows for complex data sets to be more easily interpreted, aiding in the characterization of DOM from various sources. By applying this metho...
Ph. Schmitt-kopplin - One of the best experts on this subject based on the ideXlab platform.
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Comparison of humic substances isolated from thermal water and surface water by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry
European journal of mass spectrometry (Chichester England), 2010Co-Authors: K. Kovacs, Andras Gaspar, Ph. Schmitt-kopplin, Cs. Sajgó, E. TombáczAbstract:Characterization of humic substances isolated from thermal water and surface water was carried out by elemental analysis and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Atomic ratios derived from elemental analysis represented compositional differences of humic substances. Hydrogen-to-carbon and oxygen-to-carbon atomic ratios were also calculated from molecular formulae determined by ultra high-resolution mass spectrometry. The Van Krevelen Diagram was used to illustrate the bias between the atomic ratios from elemental analysis and mass spectrometry.
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Characterization of imazamox degradation by-products by using liquid chromatography mass spectrometry and high-resolution Fourier transform ion cyclotron resonance mass spectrometry
Analytical and bioanalytical chemistry, 2007Co-Authors: Mourad Harir, Moritz Frommberger, Andras Gaspar, D. Martens, Antonius Kettrup, M. El Azzouzi, Ph. Schmitt-kopplinAbstract:The photodecomposition of imazamox, a herbicide of the imidazolinone family, was investigated in pure water. The main photoproducts from the photolysis were followed over time by liquid chromatography mass spectrometry and structures were proposed from exact mass determinations obtained by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The method comprised exact mass determination with better than 0.2 ppm mass accuracy and a corresponding structural visualization taking care of respective isotopes with an adapted Van Krevelen Diagram that enabled a systematic approach to the characterisation of the elementary composition of each photoproduct. By taking adVantage of the high resolving power of FT-ICR MS to make precise formula assignments, the derived 2D Van Krevelen Diagram (O/C; H/C; m/z) enabled one to structurally differentiate the formed photoproducts and to propose a degradation pathway for imazamox.
Stan D. Wullschleger - One of the best experts on this subject based on the ideXlab platform.
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Indexing permafrost soil organic matter degradation using high-resolution mass spectrometry
PloS one, 2015Co-Authors: Benjamin F. Mann, Hongmei Chen, Elizabeth M. Herndon, Rosalie K. Chu, Nikola Tolic, Evan F. Portier, Taniya Roy Chowdhury, Errol W. Robinson, Stephen J. Callister, Stan D. WullschlegerAbstract:Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between –1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C Van Krevelen Diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.
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Van Krevelen Diagram of the compound classes associated with the H:C and O:C-coordinate plane and CHO Index plot with N:C coordinate.
2015Co-Authors: Benjamin F. Mann, Hongmei Chen, Elizabeth M. Herndon, Rosalie K. Chu, Nikola Tolic, Evan F. Portier, Taniya Roy Chowdhury, Errol W. Robinson, Stephen J. Callister, Stan D. WullschlegerAbstract:(a) The CHO index, 2×[O]−[H][C], is plotted along the top and right edges of the Van Krevelen Diagram to illustrate their relationships and associated compound classes of organic matter assigned by Kim et al. [42]. (b) Illustration of a Van Krevelen Diagram for a water-soluble SOM sample (WSF0) extracted from an Arctic soil. Colored symbols represent different molecular components plotted in (c), which is a CHO index plot with molecular components binned according to N:C ratio: N:C = 0 (gray circles), 0 < N:C ≤ 0.1 (red triangles), 0.1 < N:C ≤ 0.2 (blue squares), 0.2 < N:C (green diamonds); Compounds with similar N:C are localized to distinct regions of the Van Krevelen Diagram in (b).
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Illustration of the molecular formulae that were either degraded (grey color) or produced (orange color) in the WSF SOM during the 40-day incubation experiment.
2015Co-Authors: Benjamin F. Mann, Hongmei Chen, Elizabeth M. Herndon, Rosalie K. Chu, Nikola Tolic, Evan F. Portier, Taniya Roy Chowdhury, Errol W. Robinson, Stephen J. Callister, Stan D. WullschlegerAbstract:(a) Van Krevelen Diagram along with CHO index showing the molecular formulae that were either degraded (grey color) or produced (orange color) in the WSF SOM after incubation. (b) CHO Index plots of the number of molecular formulae that were either disappeared in the WSF after incubation (normalized to the total of 816 formulae) or (c) produced after incubation (normalized to the total of 212 formulae).
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Molecular distribution of extracted SOM compounds from a 40-day soil warming incubation experiment.
2015Co-Authors: Benjamin F. Mann, Hongmei Chen, Elizabeth M. Herndon, Rosalie K. Chu, Nikola Tolic, Evan F. Portier, Taniya Roy Chowdhury, Errol W. Robinson, Stephen J. Callister, Stan D. WullschlegerAbstract:(a) Box-and-whisker plots of the mass distribution of SOM compounds, including the base-soluble fraction (BSF) at day 0 (BSF0) and day 40 (BSF40) and the water-soluble fraction (WSF) at day 0 (WSF0) and day 40 (WSF40). (b and c) Van Krevelen Diagram along with CHO index showing the molecular distribution of WSF SOM compounds before (b) and after (c) incubation. (d) Percentages of molecular formulae identified with CHO index values between -2 and 2 before and after soil incubation and are normalized to the total number of formulae displayed in (b) and (c). Compound classes are labeled above colored bars as follows: (A) lipids, (B) unsaturated hydrocarbons, (C) peptides, (D) aminosugars, (E) carbohydrates, (F) lignin, (G) condensed hydrocarbons, (H) tannins.
