Isotopic Analysis of Sub-Nanogram Nd Samples Using New ATONA Amplifiers
Abstract
New lines of inquiry in geochemistry and adjacent fields like nuclear forensics have created a consistent push to make high precision isotope ratio measurements of smaller samples. This push has led to a variety of new amplifier technologies for mass spectrometry like the ATONA amplifiers (Isotopx®) used in this study. The ATONA amplifiers utilize a capacitor in the amplification circuit for a faraday cup instead of a traditional high ohm resistor, leading to an amplifier with a greater dynamic range, greater long term gain stability, and lower noise. Here we present new 143Nd/144Nd data collected on a GV instruments IsoprobeT thermal ionization mass spectrometer (TIMS) upgraded with the ATONA amplifiers. We will present modified loading techniques and activators for analyses of small Nd samples to be analyzed in the oxide form (NdO+). We present a large (and expanding) data set of repeated 143Nd/144Nd analyses of a standard material for Nd loads of 10 ng (n=15), 1 ng (n=13), and 100 pg (n=30). For these analyses the external reproducibilities were 7.9 ppm, 18 ppm, and 37 ppm (2RSD), respectively. We also present 143Nd/144Nd analyses of olivine hosted melt inclusions as an example of the ability of our technique to measure high precision isotopic ratios on small samples. With the techniques presented and new ATONA amplifier technology we have generated a data set that represents a significant improvement in external reproducibility for 143Nd/144Nd measurements of 100 pg loads of Nd compared to previously published work. This work showcases the potential capability of the ATONA amplifiers using 143Nd/144Nd as an example of how this technology can be applied to additional isotopic systems to explore smaller systems. LA-UR-19-27446
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V11D0111R
- Keywords:
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- 1040 Radiogenic isotope geochemistry;
- GEOCHEMISTRY;
- 1041 Stable isotope geochemistry;
- GEOCHEMISTRY;
- 1065 Major and trace element geochemistry;
- GEOCHEMISTRY;
- 1094 Instruments and techniques;
- GEOCHEMISTRY