An assessment of calibration strategies for the quantitative and semi-quantitative analysis of calcium carbonate matrices by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)

Calibration procedures for the analysis of natural calcium carbonate-rich materials by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are herein evaluated. Calibration lines were constructed using: (a) commercially available glass reference materials; (b) high-purity calcium carbonate powder spiked with the analytes of interest, and (c) natural geological reference materials. The analytes initially considered were Ba, Cd, Fe, Mg, Mn, Pb, Sr, U and V, although some low concentrations, or lack of reference data, particularly for Cd and U, precluded a complete assessment. Calcium and indium were evaluated as internal standard candidates; data were subsequently corrected using calcium as this was the more reliable internal standard. The analysis of geological reference materials using glass calibration lines shows a systematic offset in measured versus reference, or accepted, values; future derivation of a `correction factor' may therefore be possible. The preferred calibration strategy, for the LA-ICP-MS analysis of calcium carbonate samples, uses selected natural geological reference materials.