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| Titel |
Major to ultra trace element bulk rock analysis of nanoparticulate pressed
powder pellets by LA-ICP-MS |
| VerfasserIn |
Daniel Peters, Thomas Pettke |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127353
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| Publikation (Nr.) |
 EGU/EGU2016-7219.pdf |
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| Zusammenfassung |
| An efficient, clean procedure for bulk rock major to trace element analysis by 193 nm
Excimer LA-ICP-MS analysis of nanoparticulate pressed powder pellets (PPPs) employing a
binder is presented. Sample powders are milled in water suspension in a planetary ball mill,
reducing average grain size by about one order of magnitude compared to common dry
milling protocols. Microcrystalline cellulose (MCC) is employed as a binder, improving the
mechanical strength of the PPP and the ablation behaviour, because MCC absorbs 193 nm
laser light well. Use of MCC binder allows for producing cohesive pellets of materials that
cannot be pelletized in their pure forms, such as quartz powder. Rigorous blank quantification
was performed on synthetic quartz treated like rock samples, demonstrating that
procedural blanks are irrelevant except for a few elements at the 10 ng g−1 concentration
level. The LA-ICP-MS PPP analytical procedure was optimised and evaluated using
six different SRM powders (JP-1, UB-N, BCR-2, GSP-2, OKUM, and MUH-1).
Calibration based on external standardization using SRM 610, SRM 612, BCR-2G, and
GSD-1G glasses allows for evaluation of possible matrix effects during LA-ICP-MS
analysis.
The data accuracy of the PPP LA-ICP-MS analytical procedure compares well to that
achieved for liquid ICP-MS and LA-ICP-MS glass analysis, except for element
concentrations below ∼30 ng g−1, where liquid ICP-MS offers more precise data and
in part lower limits of detection. Uncertainties on the external reproducibility of
LA-ICP-MS PPP element concentrations are of the order of 0.5 to 2 % (1σ standard
deviation) for concentrations exceeding ∼1 μg g−1. For lower element concentrations
these uncertainties increase to 5-10% or higher when analyte-depending limits of
detection (LOD) are approached, and LODs do not significantly differ from glass
analysis. Sample homogeneity is demonstrated by the high analytical precision,
except for very few elements where grain size effects can rarely still be resolved
analytically.
Matrix effects are demonstrated for PPP analysis of diverse rock compositions and basalt
glass analysis when externally calibrated based on SRM 610 and SRM 612 glasses;
employing basalt glass GSD-1G or BCR-2G for external standardisation basically eliminates
these problems. Perhaps the most prominent progress of the LA-ICP-MS PPP analytical
procedure presented here is the fact that trace elements not commonly analysed, i.e. new,
unconventional geochemical tracers, can be measured straightforwardly, including volatile
elements, the flux elements Li and B, the chalcophile elements As, Sb, Tl, Bi, and elements
that alloy with metal containers employed in conventional glass production approaches. The
method presented here thus overcomes many common problems and limitations in analytical
geochemistry and is shown to be an efficient alternative for bulk rock trace elements analysis. |
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