Performance of analytical centrifugation for the particle size analysis of real-world materials

Analytical centrifugation (AC) is a powerful technique for the measurement of particle size distributions. This study evaluates its performance for the grouping of particulate materials according to the European Commission's recommendation on the definition of a nanomaterial, which bases on the number-weighted median diameter. The focus lies on cuvette-type AC with turbidity detector and on the performance in the case of polydisperse, non-spherical real-world materials. Two grades of barium sulfate (nano and non-nano) were analysed. This study compares the repeatability of the measurement and the method precision including sample preparation, measurement and conversion into number-weighted particle size distributions. Experimental results show that the selected radiation wavelengths of 470 nm and 865 nm have only little impact on the number-weighted median diameter, but affect the intermediate precision of these values. However, the intermediate precision of the method is mainly determined by sample preparation up to 12.6% with respect to the number-weighted median diameter (x50,0). This paper provides information on particle sizing on real-world materials for the first time.