Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS

Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector–inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the appl...

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Bibliographic Details
Published in:Analytical and bioanalytical chemistry 2013-03, Vol.405 (9), p.2943-2955
Main Authors: Kappel, S., Boulyga, S. F., Dorta, L., Günther, D., Hattendorf, B., Koffler, D., Laaha, G., Leisch, F., Prohaska, T.
Format: Article
Language:English
Subjects:
Ablation
Aerosols
Analytical Chemistry
Biochemistry
Characterization and Evaluation of Materials
Chemical properties
Chemistry
Chemistry and Materials Science
Chromatography
Clusters
Composition
Computation
Data points
Food Science
Identification and classification
Isotope ratios
Isotopes
Joining
Laboratory Medicine
Lasers
Life sciences
Mass spectrometry
Methods
Monitoring/Environmental Analysis
Original Paper
Particles
Ratios
Regression
Scientific imaging
Signatures
Strategy
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Summary:Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector–inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. ‘point-by-point’, ‘integration’ and ‘linear regression slope’ method) for the computation of 235 U/ 238 U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their 235 U/ 238 U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the ‘point-by-point’ method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a ‘finite mixture model’ is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The 235 U/ 238 U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different 235 U/ 238 U isotope ratios of particles deposited on the NUSIMEP-7 test samples.
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-012-6674-3