Determination of B/Ca of natural carbonates by HR-ICP-MS

Misra, S.; Greaves, M.; Owen, R.; Kerr, J.; Elmore, A.C.; Elderfield, H.

Abstract

We report a new method for HR-ICP-MS based accurate and precise B/Ca determination from low mass natural carbonates (≤5 µg CaCO3), utilizing a mixed acid matrix (0.1 M HNO3 and 0.3 M HF) and accurate matrix matching technique. Our procedural B/Ca blank of 2.0 ± 1.0 µmol/mol, internal precision ≤1.0%, average within run external precision ≤4.0% (2σ), and rapid sample analysis (60 samples/day) make the method well suited for routine measurements. Established methods of B/Ca determination require ≥65 µg CaCO3 to achieve a comparable external precision of 3.5% (2σ). We report a B/Ca detection limit of 2 µmol/mol compared to ≥10 µmol/mol for previous methods, a fivefold improvement. The method presented here can determine a wide range of B/Ca (9.0–250 µmol/mol) in mass limited samples with considerable tolerance for matrix matching efficiency (≤±30%). The long-term reproducibility of B/Ca measured on Cambridge in-house consistency standards containing <20, ∼85, and ∼200 µmol/mol of B/Ca are ±3.7% (2σ, n = 100), ±3.9% (2σ, n = 150), and ±3.2% (2 s, n =180), respectively. A host of other trace element to Ca ratios can also be determined at comparable external precision from samples containing ≤5 µg CaCO3. This method is suitable for trace element analysis of single foraminifera shells.

Citation

Misra, S., Greaves, M., Owen, R., Kerr, J., Elmore, A., & Elderfield, H. (2014). Determination of B/Ca of natural carbonates by HR-ICP-MS. Geochemistry, Geophysics, Geosystems, 15(4), 1617-1628. https://doi.org/10.1002/2013gc005049

• Journal Article Type: Article
• Publication Date: Apr 2, 2014
• Deposit Date: Jan 28, 2014
• Publicly Available Date: Oct 12, 2016
• Journal: Geochemistry, Geophysics, Geosystems
• Publisher: American Geophysical Union
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 4
• Pages: 1617-1628
• DOI: https://doi.org/10.1002/2013gc005049