| 1. |
- Marshall, John
(författare)
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Continuous in situ measurements of water stable isotopes in soils, tree trunk and root xylem: Field approval
- 2022
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- Rationale New methods to measure stable isotopes of soil and tree water directly in the field enable us to increase the temporal resolution of obtained data and advance our knowledge on the dynamics of soil and plant water fluxes. Only few field applications exist. However, these are needed to further improve novel methods and hence exploit their full potential. Methods We tested the borehole equilibration method in the field and collected in situ and destructive samples of stable isotopes of soil, trunk and root xylem water over a 2.5-month experiment in a tropical dry forest under natural abundance conditions and following labelled irrigation. Water from destructive samples was extracted using cryogenic vacuum extraction. Isotope ratios were determined with IRIS instruments using cavity ring-down spectroscopy both in the field and in the laboratory. Results In general, timelines of both methods agreed well for both soil and xylem samples. Irrigation labelled with heavy hydrogen isotopes clearly impacted the isotope composition of soil water and one of the two studied tree species. Inter-method deviations increased in consequence of labelling, which revealed their different capabilities to cover spatial and temporal heterogeneities. Conclusions We applied the novel borehole equilibration method in a remote field location. Our experiment reinforced the potential of this in situ method for measuring xylem water isotopes in both tree trunks and roots and confirmed the reliability of gas permeable soil probes. However, in situ xylem measurements should be further developed to reduce the uncertainty within the range of natural abundance and hence enable their full potential.
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| 2. |
- Milestone, Craig B., et al.
(författare)
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Non-target profiling of bitumen-influenced waters for the identification of tracers unique to oil sands processed-affected water (OSPW) in the Athabasca watershed of Alberta, Canada
- 2021
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 35:3
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Tidskriftsartikel (refereegranskat)abstract
- Rationale The objective of this study was to identify unique chemical tracers of oil sands process-affected water (OSPW) to enable definitive discrimination of tailings pond seepage from natural bitumen-influenced waters from the Canadian Alberta McMurray formation. Methods The approach involved comparing unknowns from an unprecedented sample set of OSPW (n = 4) and OSPW-affected groundwaters (n = 15) with natural bitumen-influenced groundwaters (n = 20), using high-performance liquid chromatography/electrospray ionisation high-resolution mass spectrometry (HPLC/ESI-HRMS) operated in both polarities. Results Four unknown chemical entities were identified as potential tracers of OSPW seepage and subsequently subjected to structural elucidation. One potential tracer, tentatively identified as a thiophene-containing carboxylic acid [C15H23O3S](-), was only detected in OSPW and OSPW-affected samples, thereby showing the greatest diagnostic potential. The remaining three unknowns, postulated to be two thiochroman isomers [C17H25O3S](+) and an ethyl-naphthalene isomer [C16H21](+), were detected in one and two background groundwaters, respectively. Conclusions We advanced the state of knowledge for tracers of tailings seepage beyond heteroatomic classes, to identifying diagnostic substances, with structures postulated. Synthesis of the four proposed structures is recommended to enable structural confirmations. This research will guide and inform the Oil Sands Monitoring Program in its efforts to assess potential influences of oil sands development on the Athabasca River watershed.
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| 3. |
- Oliw, Ernst H, 1948-, et al.
(författare)
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Charge migration fragmentation in the negative ion mode of cyclopentenone and cyclopentanone intermediates in the biosynthesis of jasmonates
- 2020
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Ingår i: Rapid Communications in Mass Spectrometry. - : WILEY. - 0951-4198 .- 1097-0231. ; 34:8
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Jasmonates are formed from 12-oxo-10,15(Z)-phytodienoic acid (12-OPDA) in plants and also from 12-oxo-10-phytoenoic acid (12-OPEA) in fungi. Collision-induced dissociation (CID) of [M-H](-) generates characteristic product anions at m/z 165 [C11H17O](-). Our goal was to investigate the structure and mode of formation of this anion by CID of 12-OPDA, 12-OPEA, and 12-oxophytonoic acid (12-OPA).Methods: We investigated the CID of the [M-H](-), [M-H-CO2](-), and [M-H-H2O](-) anions using electrospray ionization and MS/MS analysis of 12-OPDA, 12-OPEA, and 12-OPA, and compared the results with the data obtained with the corresponding compounds labeled with H-2 at C-6 and C-7 and with structural and side chain analogs.Results: CID of [6,6,7,7-H-2(4)]12-OPEA and [6,6-H-2(2)]12-OPDA ([M-H](-) and [M-H-CO2](-)) showed that one or two H-2 atoms were transferred to anions at m/z 165 as judged by the signal intensities of m/z 165 + 1 or 165 + 2, respectively. CID of [6,6-H-2(2)]- and [6,6,7,7-H-2(4)]-12-OPA ([M-H](-) and [M-H-CO2](-)) yielded the loss of H-2 from the cyclopentanone and displayed the transfer of one H-2 atom in analogy to 12-OPEA. In contrast, CID of [6,6,7,7-H-2(4)]12-OPEA and [6,6,7,7-H-2(4)]12-OPA [M-H-H2O](-) demonstrated the transfer of two H-2 atoms (m/z 165 + 2). All spectra obtained by CID of [6,6,7,7-H-2(4)]12-OPDA and [6,6,7,7-H-2(4)]12-oxo-9(13),15(Z)-phytodienoic acid showed that one or two additional H-2 atoms could be transferred to this anion at m/z 167 of [6,6-H-2(2)]12-OPDA due to isotope scrambling.Conclusions: CID of 12-OPDA and 12-OPEA generates cyclopentanone enolate anions at m/z 165 by charge-driven hydride transfer as a common mechanism and by bond cleavage between C-7 and C-8 of the carboxyl side chains with either gain or loss of a hydrogen atom.
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| 4. |
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| 5. |
- Romson, Joakim, et al.
(författare)
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Chemical mass shifts of cluster ions and adduct ions in quadrupolar ion traps revisited and extended
- 2023
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 37:3
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Tidskriftsartikel (refereegranskat)abstract
- RationaleChemical mass shifts in quadrupolar ion traps have been studied previously but only for a limited number of analytes and mass ranges. Here, mass shifts of cluster ions, commonly used as calibrants, and other analytes are qualitatively evaluated on the Bruker amaZon spherical ion trap (QIT) and the Finnigan LXQ linear ion trap (LIT). To extend the mass range from previous experiments m/z up to 4000 are investigated. MethodsChemical mass shifts of CsI, Y(HCOO)(3), and NaCF3COO cluster ions, CF3COO-, Na+, and Cs+ adduct ions, protonated commercial calibration solutions and peptides, and deprotonated peptides were investigated on the Bruker amaZon speed QIT and some of these were also investigated on the Finnigan LXQ LIT. ResultsOn both instruments, peak distortions and mass shifts toward lower m/z became apparent as m/z approached 1000. To some extent, the issues were more severe at slower scans. Peak distortions included loss of resolution, tailing, or fronting and were different between the amaZon QIT and the LXQ LIT. The noncluster and nonadduct ions analyzed showed no obvious mass shifts or peak distortions under the same analysis conditions. ConclusionsAs expected, the ion traps investigated here showed mass shift and peak distortion issues, and such issues persisted at m/z up to 4000 on both instruments. Peak distortions were different between the amaZon QIT and the LXQ LIT, and were not always visible despite mass shifts. Both mass shifts and peak distortions make cluster ions and some adduct ions unsuitable for ion trap calibration.
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| 6. |
- Romson, Joakim, et al.
(författare)
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SpheriCal(R)-ESI : A dendrimer-based nine-point calibration solution ranging from m/z 273 to 1716 for electrospray ionization mass spectrometry peptide analysis
- 2021
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 35:5
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Tidskriftsartikel (refereegranskat)abstract
- Rationale A calibration solution for mass spectrometry needs to cover the range of interest with intense and sufficiently narrowly spaced peaks. Limited options fulfilling this may lead to compromises between performance and ease of use. SpheriCal(R)-ESI was designed to combine high calibration performance for electrospray ionization (ESI) mass spectrometric analysis of peptides in positive mode with quick and easy use. Methods The developed calibration solution was tested using three mass spectrometers: two ion traps and one tandem quadrupole. The m/z errors of SpheriCal(R)-ESI itself and of a tryptic digest of cytochrome C were measured after calibration. The results were compared with those achieved with ESI Tuning Mix. The memory effects of the dendrimers, and contamination from Na+ in the calibration solution, were evaluated. Results SpheriCal(R)-ESI showed good shelf life as powder and was quickly reconstituted for use. Achieving intense and stable signals was straightforward. The accuracies and precisions were as expected for the instruments. SpheriCal(R)-ESI was more precise and at least as accurate as ESI Tuning Mix. The memory effects and Na+ contamination were found to be negligible in typical peptide solvents. In addition, the dendrimers showed predictable dissociations with product ions common to collision-induced dissociation in both ion trap and tandem quadrupole mass spectrometers. Conclusions SpheriCal(R)-ESI provided easily accessible calibration by showing intense signals at low infusion rates and at source settings equal or similar to those used in peptide analysis. Nine calibration points in the range of interest gave precise and accurate results. Memory effects and contamination were negligible even without rinsing.
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| 7. |
- Yu, Longfei, et al.
(författare)
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What can we learn from N2O isotope data? - Analytics, processes and modelling
- 2020
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 34:20
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Tidskriftsartikel (refereegranskat)abstract
- The isotopic composition of nitrous oxide (N2O) provides useful information for evaluating N2O sources and budgets. Due to the co-occurrence of multiple N2O transformation pathways, it is, however, challenging to use isotopic information to quantify the contribution of distinct processes across variable spatiotemporal scales. Here, we present an overview of recent progress in N2O isotopic studies and provide suggestions for future research, mainly focusing on: analytical techniques; production and consumption processes; and interpretation and modelling approaches. Comparing isotope-ratio mass spectrometry (IRMS) with laser absorption spectroscopy (LAS), we conclude that IRMS is a precise technique for laboratory analysis of N2O isotopes, while LAS is more suitable forin situ/inline studies and offers advantages for site-specific analyses. When reviewing the link between the N2O isotopic composition and underlying mechanisms/processes, we find that, at the molecular scale, the specific enzymes and mechanisms involved determine isotopic fractionation effects. In contrast, at plot-to-global scales, mixing of N2O derived from different processes and their isotopic variability must be considered. We also find that dual isotope plots are effective for semi-quantitative attribution of co-occurring N2O production and reduction processes. More recently, process-based N2O isotopic models have been developed for natural abundance and(15)N-tracing studies, and have been shown to be effective, particularly for data with adequate temporal resolution. Despite the significant progress made over the last decade, there is still great need and potential for future work, including development of analytical techniques, reference materials and inter-laboratory comparisons, further exploration of N2O formation and destruction mechanisms, more observations across scales, and design and validation of interpretation and modelling approaches. Synthesizing all these efforts, we are confident that the N2O isotope community will continue to advance our understanding of N2O transformation processes in all spheres of the Earth, and in turn to gain improved constraints on regional and global budgets.
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