Open AccessAccuracy, standardization, and interlaboratory calibration standards for foraminiferal Mg/Ca thermometry
Author(s) -
Greaves Mervyn,
Barker Stephen,
Daunt Caroline,
Elderfield Henry
Publication year - 2005
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2004gc000790
Subject(s) - calcite , calibration , carbonate , standard solution , certified reference materials , mineralogy , analytical chemistry (journal) , calcium carbonate , standard addition , silicate , accuracy and precision , foraminifera , strontium , seawater , reproducibility , geology , chemistry , environmental chemistry , materials science , chromatography , metallurgy , detection limit , mathematics , statistics , oceanography , organic chemistry , benthic zone
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.