Modern methods for the measurement and characterization of particle size in geosdandards reference materials

The geosdandards reference materials have been the metrological standard of geoanalysis. They are frequently used in geoanalysis and play an important role in the quality controlling of analytical results, instrument calibration and analytical method evaluation. Most of the geosdandards reference materials are powder materials, while the particle size is a very important characteristic index for powder materials. From the beginning of the preparation of reference materials, the particle size of geological reference materials had been measured by sieving method; In recent years, laser particle size analyzer had been introduced into the preparation of ultra-fine size reference materials, so the results of particle size analysis can be represented by the intuitive particle size distribution plot and concise specific particle sizes. The introduction of this technique improved the measurement and characterization level for particle size of geological powder reference materials markedly. In this paper, we report the particle size distribution results obtained by this new technique for the typical geosdandards reference materials, which had been widely used for the analysis of geological samples. It will be helpful for the correct usage and the evaluation of sampling uncertainty. In addition, we introduced the modern methods measuring particle size of powder materialment and discussed the differences of concept between geoanalysis and particle size analysis. Some suggestions are presented for the future measurement and characterization of particle size for geological reference materials as well as for routine geoanalytical samples.