ANSTO Publications Online >
Conference Publications >
Conference Publications >

Please use this identifier to cite or link to this item: http://apo.ansto.gov.au/dspace/handle/10238/3837

Title: Improving the accuracy of aluminium assay in purified quartz for in situ cosmogenic exposure dating
Authors: Fujioka, T
Fink, D
Mifsud, C
Keywords: Aluminium
Quartz
Quantitative Chemical Analysis
Age Estimation
Accuracy
ICP Mass Spectroscopy
Issue Date: 24-Mar-2011
Publisher: 12th International Conference on Accelerator Mass Spectrometry (AMS-12)
Citation: Fujioka, T., Fink, D., Mifsud, C. (2011). Improving the accuracy of aluminium assay in purified quartz for in situ, 12th International Conference on Accelerator Mass Spectrometry (AMS 12), 20th - 25th March 2011. Museum of New Zealand: Te Papa Tongarewa, Wellington, New Zealand.
Abstract: Precise and accurate measurement of the natural aluminium content in purified quartz powder, [Al], extracted from surface bedrock and/or sediment samples for in situ cosmogenic nuclide dating is critical for reliable 26Al exposure ages and 26Al/10Be ratios for burial dating. Numerous articles have cited issues regarding reliability of 26Al ages paired to 10Be ages, not only due to poor statistical error, but also due to uncertainty in [Al]. Loss of Al during aliquot preparation for ICPOES from bulk HF solutions of dissolved quartz or inaccurate assay via ICP (or AA) will result in reduced 26Al concentrations. In turn this will, depending on magnitude of the loss with respect to typical age errors, lead to lower-than-expected 26Al ages when compared to corresponding 10Be ages. If the loss is excessive, this may result in depressed 26Al/10Be ratios and thus a false burial signal. Over the past 4 years we have performed repetitive Al assays from a parent HF solution prepared from ~25 g of a low-iron glass sand (NIST-165a; ~320 ppm [Al]) using identical methods as for all quartz samples. The solution was used as an in-house laboratory standard for [Al] and shows a limiting 1σ of ±5% (n ~50) via ICP-OES at a commercial laboratory. The spread in paired NIST-165a duplicates measured per batch is better than ±1%. To determine the accuracy of our procedures, we prepared sets of solutions (1–10 ppm Al) from 3 different quartz powders using the standard addition method. Initial results indicate a 3-7% offset between [Al] based on the standard addition method and that based on the conventional calibration curve. Copyright (c) 2011 AMS12.
URI: http://www.gns.cri.nz/ams12/AMS-12_Abstracts_Book_Final.pdf
http://apo.ansto.gov.au/dspace/handle/10238/3837
Appears in Collections:Conference Publications

Files in This Item:

There are no files associated with this item.

Items in APO are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback