کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6437029 | 1637674 | 2011 | 15 صفحه PDF | دانلود رایگان |
We report composition-dependent matrix effects in the in-situ measurement of Mg and Si isotope ratios by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) in natural and synthetic silicate glasses. These were determined using two 193 nm wavelength excimer laser ablation-multicollector ICPMS systems, one employing a double-focusing mass spectrometer (ThermoFinnigan Neptune) and one employing a single-focusing mass spectrometer with a hexapole/collision cell (GV Instruments IsoProbe). Observed matrix effects in isotopic measurements by LA-ICPMS range from subtle (i.e., less than â 0.7â° per amu for Si isotope measurements in natural and synthetic glasses in all instrumental configurations) to significant but mass-dependent (i.e., less than 1.2â° per amu for Mg isotope measurements performed using the Neptune) to large and significantly non-mass-dependent (i.e., up to 6â° mass dependent/3â° non-mass dependent for Mg isotope measurements of natural glasses made with the IsoProbe). Composition-dependent differences in the magnitude and direction of within-run isotopic fractionation (particularly for Mg isotope measurements) suggest that isotopic fractionation at the site of ablation is the main source of matrix effects in measurements employing the double-focusing mass spectrometer. However, the large and significantly non-mass dependent (but systematic and reproducible) matrix effects affecting LA-ICPMS Mg isotope data obtained using the single-focusing IsoProbe appear to be largely due to non-linear scattering processes occurring in the hexapole/collision cell as Mg becomes increasingly diluted by matrix elements.
Research Highlights⺠Mg and Si isotopes measured by LA-MC-ICPMS in glasses show matrix effects. ⺠Composition-dependent effects are larger for Mg than for Si isotope measurements. ⺠Largest Mg isotope matrix effects in measurements using single-focusing MC-ICPMS.
Journal: Chemical Geology - Volume 281, Issues 1â2, 2 February 2011, Pages 26-40