A Comparison of Bulk with Micro-Volume Elemental Values for NIST SRM 610 and NIST SRM 612

Published

June 26, 2025

Author(s)

Nicholas Sharp, Maria Isabel Vega Martinez, Ruthmara Corzo, Blaza Toman, Rick Paul, Jamie Weaver

Abstract

NIST SRM 610 and 612 (Trace Elements in Glass) are routinely used for microanalytical measurements but were designed to be bulk-scale reference materials. This study investigates an approach to quantify the differences between values for elements obtained using the bulk techniques ICP-OES, INAA and CNPGAA, and values obtained using the predominant microanalytical technique LA-ICP-MS. The results from bulk techniques and LA-ICP-MS were also compared with currently accepted mass fractions reported in the Certificates of Analysis (CoA) and the literature. The element suite measured was based on the needs of the forensic and geological microanalysis communities, and included B, Ce, Hf, K, La, Li, Ti and Zr. These additional elements are either not included or do not have uncertainty values in the CoAs for NIST SRMs 610 and 612 but are available as community consensus values, which include uncertainties. The measurement results were processed using Monte Carlo (MC) uncertainty analysis for each technique to provide a comprehensive calculation of expanded uncertainties for use in future research. Measurements of mass fractions of the same element both within and between fragments in the LA-ICP-MS data were observed to be correlated due to the use of only one calibration material, which was Float Glass Standard (FGS) 2, as that reference material is not directly traceable to NIST SRMs 610 and 612, and is predominantly used in the forensic community. The MC treatment was expected to cause increases in the overall uncertainty values compared with traditional Guide to the Expression of Uncertainty in Measurement (GUM) treatment for all measurements, which was the case for LA-ICP-MS measurements of all elements in NIST SRM 610 and NIST SRM 612 (except for Mn in NIST SRM 610). However, for bulk measurements of Ce, Li and Rb in NIST SRM 610, and bulk measurements of Li, Mn, Ti and Zr for NIST SRM 612, the uncertainty decreased due to MC more precisely determining the uncertainty contribution compared with a more conservative approximation from GUM. All results were compared by using En scores to assess the relative agreement between bulk- and micro-scale measurements, CoA values and to community consensus values. The findings point out the limitations of the current forensic glass reference materials for high precision microanalytical measurements, especially due to the relatively high uncertainty values associated with Float Glass Standard (FGS) 2. This situation underscores the need for new reference materials specifically designed for homogeneity at the micro-scale for trace element measurement.

Citation

Geostandards Newsletter-The Journal of Geostandards and Geoanalysis

Pub Type

Journals

Download Paper

https://doi.org/10.1111/ggr.12615

Local Download

Keywords

Microanalysis, Glass, Uncertainty, LA-ICP-MS, INAA, SRM

Citation

Sharp, N. , Vega Martinez, M. , Corzo, R. , Toman, B. , Paul, R. and Weaver, J. (2025), A Comparison of Bulk with Micro-Volume Elemental Values for NIST SRM 610 and NIST SRM 612, Geostandards Newsletter-The Journal of Geostandards and Geoanalysis, [online], https://doi.org/10.1111/ggr.12615, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956773 (Accessed July 12, 2025)