The certification of particle size distribution of corundum : ERM-FD069

This report describes the production of ERM-FD069, which is a corundum material certified for the particle size distribution as determined by laser diffraction (ISO 13320) and optical microscopy (ISO 13322). This material was produced following ISO Guide 34:2009 and is certified in accordance with ISO Guide 35. Two grades of commercial corundum were mixed, repeatedly divided and packed into glass bottles. These bottles are equipped with three flow-breakers made of glass to allow thorough homogenisation of the material inside the bottle. Between unit-homogeneity was quantified and stability during dispatch and storage was assessed in accordance with ISO Guide 35:2006. The minimum sample intake was determined as the lowest amount that gave repeatable results in the characterisation study. The material was characterised by an interlaboratory comparison of laboratories of demonstrated competence and adhering to ISO/IEC 17025. Technically invalid results were removed but no outlier was eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties related to possible inhomogeneity, instability and characterisation. The material is intended for the quality control and assessment of method performance. As with any reference material, it/they can be used for establishing control charts or be used in validation studies. The CRMs is available in glass bottles containing at least 40 g of corundum powder. The minimum amount of sample to be used is 100 mg.