Accuracy, standardisation and interlaboratory calibration standards for foraminiferal Mg/Ca thermometry [Technical Brief]

Greaves, M. J. and Barker, S. and Daunt, C. and Elderfield, H. (2005) Accuracy, standardisation and interlaboratory calibration standards for foraminiferal Mg/Ca thermometry [Technical Brief]. G3 Geochemistry Geophysics Geosystems, 6 (2). DOI 10.1029/2004GC000790

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Abstract

The use of liquid and solid standards for foraminiferal Mg/Ca and Sr/Ca determinations and interlaboratory calibration has been investigated. Preparation of single element standard solutions from primary solid standard material enables the preparation of mixed standard solutions with Mg/Ca and Sr/Ca ratios of known accuracy to better than 0.1%. We also investigated commercial reference materials to determine whether existing carbonate standards could be used as reference material for Mg/Ca determinations in foraminiferal calcite. We propose that, in the absence of a pure calcium carbonate standard certified for Mg/Ca, ECRM 752-1, a limestone CRM containing Mg/Ca within the range of typical foraminifera, is a suitable solid standard for interlaboratory calibration. Replicate Mg/Ca determinations showed that, provided silicate phases are removed by centrifugation, this material is homogenous within the precision of daily instrumental Mg/Ca determinations over a range of sample weights from 10 to 1000 mg, taken from two separate bottles of ECRM 752-1. Results gave an average value of Mg/Ca = 3.75 mmol/mol (0.015 s.d., 0.41% r.s.d.) on 118 determinations from the two bottles.

Item Type: Article
Uncontrolled Keywords: 2005 PUBL 2005 AREP IA46 IA47
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: G3 Geochemistry Geophysics Geosystems
Volume: 6
Identification Number: 10.1029/2004GC000790
Depositing User: Sarah Humbert
Date Deposited: 11 Apr 2011 10:52
Last Modified: 23 Jul 2013 09:58
URI: http://eprints.esc.cam.ac.uk/id/eprint/1663

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