Liu, Chun‐Yao;
Pogge von Strandmann, Philip AE;
Tarbuck, Gary;
Wilson, David J;
(2022)
Experimental Investigation of Oxide Leaching Methods for Li Isotopes.
Geostandards and Geoanalytical Research
, 46
(3)
pp. 493-518.
10.1111/ggr.12441.
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Abstract
To examine the applicability of different leaching methods used to extract secondary oxides from silicate solids for lithium isotope (δ7Li) analysis, this study has conducted leaching experiments on five different types of silicate solids, including a fresh basalt, two weathered basalts, a Yellow River sediment (loess-dominated) and a shale. Four factors were assessed in the experiments: the concentration of the leaching reagent hydroxylamine hydrochloride (HH), the leaching temperature (20 °C versus 95 °C), the leaching time and the reagent/solid ratio. Based on elemental concentrations and Li isotopes, 0.04 mol l-1 hydroxylamine hydrochloride (HH) in 25% v/v acetic acid at room temperature for 1 hour with 40 ml g-1 reagent/solid ratio is recommended. At high temperature, low δ7Li and high magnesium/iron ratios indicate that minerals other than secondary oxides are dissolved. With increased leaching time, there is no evidence for Li isotopic fractionation at room temperature. However, longer leaching time or increased reagent/solid ratios may increase the risk of leaching from non-oxide phases. Meanwhile, results suggest that low concentrations of HH are not sufficient to target the secondary oxides evenly, while high concentrations of HH can leach out more non-oxides. We also examined the optimal oxide leaching method within a full sequential leaching procedure (i.e., exchangeable, carbonate, oxide, clay and residual phases). Elemental concentrations show that no elements exist exclusively in oxides, so it is essential to analyse multi-elemental concentrations to verify that the leaching has accessed this phase in a given sample. Comparing secondary oxides with their corresponding solutions, we estimate the isotopic fractionation (Δ7Lioxide-solution) is -16.8‰ to -27.7‰.
| Type: | Article |
|---|---|
| Title: | Experimental Investigation of Oxide Leaching Methods for Li Isotopes |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1111/ggr.12441 |
| Publisher version: | https://doi.org/10.1111/ggr.12441 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Li isotopes, oxides, sequential leaching, hydroxylamine hydrochloride, BCR-2, SGR-1b, Yellow River sediment |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10149587 |
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