Isotopic analysis of sub‐nanogram neodymium loads using new ATONA™ amplifiers

Abstract

Rationale Emerging research in the geological and nuclear forensics fields demands increasing analytical precision of isotope ratio measurements with decreasing sample sizes. Here we demonstrate the capability of a newly developed amplification technology to make precise neodymium (Nd) isotopic measurements on 100‐pg standard loads. Methods The reference materials were analyzed as NdO+ to increase the ionization efficiency of the small analyte loads. The Nd isotopic measurements were made using an IsotopX Isoprobe‐T thermal ionization mass spectrometer upgraded with the ATONA™ amplifier system. The ATONA™ amplifier system uses capacitance‐based amplification as opposed to traditional impedance‐based amplification. Results The long‐term gains of the ATONA™ amplifiers are shown to have less than 1 ppm variability. Repeat measurements of the JNdi‐1 reference material demonstrate the ability of the ATONA™ amplification technology to make measurements of 143Nd/144Nd ratios with 23 ppm external reproducibility on 100‐pg loads. The effect of increasing integration time on analytical reproducibility is also displayed as increasing integration time from 10 to 30 s reduced the external measurement uncertainty from 37 to 23 ppm. Conclusions These measurements represent an improvement of more than a factor of 3 in external measurement reproducibility relative to previously published 143Nd/144Nd measurements of 100‐pg loads. This new technology will allow for the measurement of smaller samples for precise isotope ratios and open new avenues of research in the geological and nuclear forensic communities.

New Perspectives on the 143Nd/144Nd Palaeoceanographic Tracer on Foraminifera: The State‐of‐the‐Art Frontiers of Analytical Methods

“…Our experiments with 100 pg Nd loads of JNd‐1 using 10 13 Ω amplifiers and two different approaches–double and single filament configurations–yielded identical average 143 Nd/ 144 Nd values (Figure 2) practically identical with those from previous studies on similar Nd loads (Chu et al., 2009; Reinhard et al., 2021), suggesting that the two methods are equally accurate. Similarly, the overlapping results for JLs‐1 and JCp‐1 reference materials (limestone and coral, respectively) for the two methods employed argue for the overall robustness of single filament measurements.…”

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

“…Thermal ionisation mass spectrometry with an ATONA amplier upgrade was used by Reinhard et al for measuring 143 Nd/ 144 Nd isotope ratios from starting materials with mass of only 100 pg. 182 Compared with the previous setup, the external measurement reproducibility was improved by a factor of three, with an external measurement uncertainty of 23 ppm, contributing to measurement of smaller samples for geological and forensic applications.…”

Application of ATONA Amplifiers to the Measurement of Uranium Isotopic Ratios by Thermal Ionization Mass Spectrometry

“…Recently Isotopx Ltd. (Manchester, UK) developed the ATONA (Atto- to Nano-Amp) amplifier system which utilizes capacitance based amplification, replacing the traditional high ohmage resistor amplifier used with traditional Faraday-based detection systems. ,, This new technology allows a Faraday cup to have an extremely large dynamic range (10 –9 A to 10 –18 A), with very low dark noise (10 –18 A). The fundamental physical properties of capacitors provide an advantage in dark noise over resistors; capacitor noise scales as the inverse of time, whereas with a resistor noise scales as the inverse of the square root of time .…”

“…The broad utility of uranium isotopic composition data has created a demand to measure isotopic ratios with increasing precision for small sample sizes while maintaining or increasing sample throughput. This demand has pushed recent innovations in multicollector mass spectrometry, particularly in detection systems. ,− One of the most promising recent developments for uranium isotope measurements is the ATONA capacitive transimpedance amplifier developed by Isotopx Ltd., which can accurately measure extremely low signals without sacrificing the dynamic range inherent to Faraday-based detection systems. , …”