Nanoparticle Analysis for Reference Materials: The Small-Angle X-ray Scattering Method

Reliable certification of nanoparticle reference materials is crucial for advancing nanoparticle analysis. Here, we demonstrate the use of small-angle X-ray scattering (SAXS) as a robust method for certifying a silver nanoparticle reference material (BAM-N008) exhibiting exceptional long-term stability─maintaining its properties for at least 10 years without special storage precautions. Comprehensive characterization in accordance with ISO 17867 and ISO 23484 supports the suitability of SAXS for nanoparticle metrology. Homogeneity and stability studies underpin value assignment and uncertainty evaluation, with metrologically traceable values established for particle diameter and number density, and reference values assigned for the width of the size distribution and particle mass concentration. The assigned values are D = 5.8 nm, σ = 1.33 nm, N = 3.7 × 10-6 mol L-1, and c = 3.0 g L-1, with expanded uncertainties (k = 2) of 9%, 14%, 19%, and 17%, respectively. These results provide a reliable basis for validating and verifying analytical methods for nanoparticle dispersion analysis.