| 1. |
- Liao, Xin, et al.
(författare)
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Allanite U–Th–Pb geochronology by ion microprobe
- 2020
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Ingår i: Journal of Analytical Atomic Spectrometry. - : The Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 35:3, s. 489-497
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Tidskriftsartikel (refereegranskat)abstract
- Allanite, an epidote group mineral, occurs as a common accessory mineral in igneous, metamorphic rocks and hydrothermal deposits. It contains radioactive elements Th and U, making it a valuable U–Th–Pb geochronometer for various geological processes. Due to the structural and compositional complexity of allanite, in situ dating method is a better choice when the allanite is heterogeneous or has crystallized in multi-stage events. The wide variation of chemical compositions, however, raises the potential for matrix effects and complicates the use of in situ methods for allanite U–Th–Pb chronology. To address this issue, we made a comprehensive investigation on allanite U–Th–Pb chronology using Secondary Ion Mass Spectrometry (SIMS). Five allanite samples (CAP, Daibosatsu, SQ-51, Toba OTT, TARA allanite) with variable elemental compositions and common lead concentrations have been used. Allanites with variations in FeO (from 12.8 to 16.1 wt%) and similar ThO2 contents (around 1–2%) do not show significant matrix effects, as suggested by a previous study. While, obvious changes in calibration parameters (UO2+/U+, ThO2+/Th+) were noticed for allanites with a large range of Th contents (from 300 ppm to 2.0 wt%). By employing power law relationships between Pb+/U+versus UO2+/U+, Pb+/Th+versus ThO2+/Th+ with suitable exponentials, we do not observe obvious matrix effects with ThO2 concentrations variations. This study demonstrates that allanite can be a good geochronometer for multi-stage mineralization of hydrothermal deposits, providing valuable complementary information to zircon and monazite.
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| 2. |
- Lindahl, Patric, et al.
(författare)
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Performance and optimisation of triple quadrupole ICP-MS for accurate measurement of uranium isotopic ratios
- 2021
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 36:10, s. 2164-2172
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Tidskriftsartikel (refereegranskat)abstract
- The performance characteristics of the Agilent 8900 triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) system were evaluated and optimised concerning stability in measurements of uranium isotopic ratios. Multiple measurement parameters were evaluated for the determination of U isotopic ratios in certified standard solutions containing U-233, U-235 and U-238. Large irregular biases during repeated measurements of U isotopic ratios were observed using two identical ICP-MS/MS instruments. Depending on the mass filter resolution settings, the accuracy of U isotopic ratios can deviate up to 100% from the certified reference value. These variations in U isotopic ratios are primarily recognised as irregular drifts in the mass calibration of the two mass filters. This mass calibration drift is dependent on the isotope mass with a more pronounced drift for heavier isotopes. In order to solve the problem the resolution settings were optimised for both mass filters, which resulted in considerable improvement in precision and accuracy. A precision of 0.07% (relative standard deviation) for long-term measurement of U-233/U-235 ratios was achieved. Mass bias corrected U isotopic ratios agree very well with certified reference values with overall relative deviations from reference values of 0.005% and 0.17% for the SQ mode and MS/MS mode, respectively. The impact of the first mass filter in the MS/MS mode has a significant effect on the mass bias discrimination process and hence the accuracy of U isotopic ratios.
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| 3. |
- Redaa, A., et al.
(författare)
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Assessment of elemental fractionation and matrix effects during in situ Rb-Sr dating of phlogopite by LA-ICP-MS/MS: implications for the accuracy and precision of mineral ages
- 2021
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 36:2, s. 322-344
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Tidskriftsartikel (refereegranskat)abstract
- Laser-ablation inductively-coupled plasma tandem mass-spectrometry (LA-ICP-MS/MS) allows for rapid and interference free analyses of Rb and Sr isotopes, permitting in situ Rb-Sr dating of minerals. However, the general lack of matrix matched reference materials remains one of its main obstacles, affecting both precision and accuracy. This study systematically investigates the impact of matrix effects and down-hole fractionation (DHF) on the in situ Rb-Sr ages of an igneous phlogopite mineral (MDC) analysed by an ICP-MS/MS using two different LA systems: (i) a RESOlution ArF (193 nm) excimer and (ii) a NWR (213 nm) Nd-YAG laser system. A phlogopite reference material (Mica-Mg), originating from the same location as the MDC, was prepared as a pressed nano-powder pellet (NP) and used in this study as a primary reference material. The results revealed that the accuracy of the Rb-Sr ages is typically within about 3% (for 70% of analysed samples), but occasionally higher ranging between 4 to 8% (ca. 30% of cases). We hypothesize that the above bias and uncertainty in the Rb-Sr ages are related to matrix effects between Mica-Mg-NP and MDC, due to their specific ablation characteristics and different physical properties. In addition, the elemental fractionation effects observed in this study for Rb-87/Sr-86 are also dependent on laser wavelength (i.e., 193 nm vs. 213 nm). Hence, developing an improved nano-powder reference material, or a mineral or glass with better matrix matching to natural phlogopite minerals would be desirable to further improve the accuracy of in situ Rb-Sr dating. Currently, regular monitoring of secondary and matrix-matched reference minerals such as the MDC phlogopite can be used to assess and evaluate the accuracy of in situ Rb-Sr dating of phlogopite, yielding ages within accuracy of ca. 3% or better.
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| 4. |
- Tulej, Marek, et al.
(författare)
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Determination of the microscopic mineralogy of inclusion in an amygdaloidal pillow basalt by fs-LIMS
- 2021
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 36:1, s. 80-91
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Tidskriftsartikel (refereegranskat)abstract
- We present chemical depth profiling studies on mineralogical inclusions embedded in amygdale calcium carbonate by our Laser Ablation Ionisation Mass Spectrometer designed for in situ space research. An IR femtosecond laser ablation is employed to generate ions that are recorded by a miniature time-of-flight mass spectrometer. The mass spectra were measured at several locations on the sample surface and yield chemical depth profiles along the depth length of about 30 mu m. The presence of oxides and sulphides within inclusion material allows us to derive elemental abundance calibration factors (relative sensitivity coefficients, RSCs) for major and minor elements. These are obtained from the atomic intensity correlations performed on the depth profiling data. With the RSCs corrections the quantitative analysis of more complex mineralogical phases within the inclusion is conducted by correlating atomic abundance fractions in ternary diagrams, typically used in geology. The spatial resolution of the depth profiles was sufficient to study chemically distinct micrometre-sized objects, such as mineralogical grains and thin layers of minerals including micrometre-sized filamentous structures. The method presented here is well-suited for the quantitative chemical analyses of highly heterogeneous materials where the ablation condition can vary locally with the material composition making the application of standard reference materials less accurate. The presented method is developed to distinguish between abiotic and biological material while searching for micrometre-sized extinct or extent life forms on the surfaces of Solar System bodies.
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| 5. |
- Tuoriniemi, Jani, et al.
(författare)
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Measurement of number concentrations and sizes of Au nano-particles spiked into soil by laser ablation single particle ICPMS
- 2020
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 35, s. 1678-1686
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Tidskriftsartikel (refereegranskat)abstract
- A novel method to directly quantify nanoparticles (NPs) in a soil matrix by laser ablation single particle inductively coupled plasma mass spectrometry (LA-sp-ICPMS) was developed. Different concentrations of 60, 100, or 250 nm diameter gold NPs (AuNP) were deposited directly on polyether sulfone (PES) ultrafiltration membranes or immersed in soil. The ICPMS sensitivity was calibrated using aqueous dissolved Au standards and an aqueous AuNP size standard dispersion was used to calculate the transmission efficiency. In the case of the soil samples, sizing proved to be more accurate when calibration occurred while ablating a non-spiked soil. A linear relation was found between the spiked AuNP number concentrations and the particle event frequencies measured in the ablated area. Particle recovery on PES filters ranged only between 29 to 42% and recovery of soil-spiked AuNP on thin tape was between 15 and 60% and increased with size. However, 70-85% mass recovery in the ablated area was obtained when the soil sample was deposited on a thicker, opaque double sided tape suggesting that the substrate material is instrumental in absorbing excess laser energy thus enhancing recovery. The rate of soil ablation and mass transfer into the plasma was quantified to calculate the recovery using the same soils spiked with indium. The presented method thus has significant potential to be used for routine quantification of the particle size distributions of engineered or natural NPs in soil and possibly other powder samples with significantly fewer artifacts than extraction followed by aqueous analysis.
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| 6. |
- Velimirovic, Milica, et al.
(författare)
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Mass spectrometry as a powerful analytical tool for the characterization of indoor airborne microplastics and nanoplastics
- 2021
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 36:4, s. 695-705
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Forskningsöversikt (refereegranskat)abstract
- Development of analytical methods for the characterization (particle size determination, chemical identification, and quantification) of the low mu m-range microplastics (MPs; 1-10 mu m) and nanoplastics (NPs; 1 nm to 1 mu m) in air - coarse (PM10; <10 mu m), fine (PM2.5; <2.5 mu m) and ultrafine (PM1; <1 mu m) particulate matter - is a quickly emerging scientific field as inhalation has been identified as one of the main routes of human exposure. The respiratory tract may serve as both target tissue and port of entry to the systemic circulation for the inhaled MPs and NPs with their small particle size. As an outcome, the interest of the scientific community, policy makers, and the general public in indoor airborne MPs and NPs increased tremendously. However, there is a lack of detailed knowledge on the indoor and outdoor sources of MPs and NPs, their levels, and their health impact. This is mainly related to a lack of standardized sampling and analytical methods for size determination, chemical identification, and quantification. In this review, recent developments in mass spectrometry-based analytical methods for size determination, chemical identification, and quantification of the MPs and NPs in indoor air and dust, are discussed.
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| 7. |
- Zhu, Zhifeng, et al.
(författare)
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Effect of gas temperature on composition concentration measurements by laser-induced breakdown spectroscopy
- 2023
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 38:2, s. 382-390
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced Breakdown Spectroscopy (LIBS) is widely applied to the quantitative measurement of gas composition concentrations. However, studies on the effect of gas temperature on LIBS are still lacking. Here, we investigated the effect of gas temperature on LIBS in terms of composition measurements in an air flow field. The air flow field was heated using a resistance wire to different gas temperatures ranging from 300-930 K in a heating tube. We evaluated the effect of gas temperature on the ratio of spectral line pairs, which is typically used for the calibrations of LIBS measurements. The variations in gas temperature change the ratio of spectral line pairs, which ultimately affects the accuracy of LIBS measurements. Further, the effect of gas temperature on the accuracy of LIBS measurements with different acquisition strategies was compared. The effects of gate width and delay time were investigated. An optimized acquisition strategy was proposed to reduce the effect of gas temperature on LIBS measurements. For LIBS measurements in gas flow fields, the effect of gas temperature on LIBS measurements can be reduced by using a large gate width and a suitable long delay time. The optimized acquisition strategy uses long-time averaging after an appropriate delay time to reduce the effect of gas temperature on plasma parameters. Finally, higher laser energy also helps to reduce the effect of gas temperature on LIBS measurements. In this paper, the LIBS measurement error caused by increasing the gas temperature from 300 K to 930 K is about 5%, roughly 0.8% per 100 K, with the optimized acquisition strategy. This paper can provide some help for LIBS measurements in gas samples with temperature variations.
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