Nano-Powdered Calcium Carbonate Reference Materials: Significant Progress for Microanalysis?

Homogeneity, mass fractions of about forty trace elements and Sr isotope composition of Ca carbonate reference materials (RMs) between original and nano-powdered pellets are compared. Our results using nanosecond and femtosecond LA-(MC)-ICP-MS show that the nano-pellets of the RMs MACS-3NP, JCp-1NP and JCt-1NP are about a factor of 2–3 more homogeneous than the original samples MACS-3, JCp-1 and JCt-1, and are therefore much more suitable for microanalytical purposes. With the exception of Si, the mass fractions of the synthetic RM MACS-3 agree with its fine-grained analogue MACS-3NP. Very small, but significant, differences between original and nano-pellets are observed in the RMs JCp-1 and JCt-1 for some trace elements with very low contents, indicating the need for re-certification. Strontium mass fractions in the analysed RMs are high (1500–7000 mg kg−1), and their isotope compositions determined by LA-MC-ICP-MS in the original and the nano-pellets agree within uncertainty limits.