The European Commission’s Joint Research Centre (JRC) has published a Technical Report, entitled Basic Comparison of Particle Size Distribution Measurements of Pigments and Fillers using Commonly Available Industrial Methods. Work was carried out ‘to evaluate a number of analytical methods of measuring particle size distributions as required for classification with respect to the EC Recommendation for the definition on nanomaterials’; however, the authors state that guidelines ‘regarding some aspects of the definition and its implementation’ are necessary in order to avoid ‘lab-to-lab variability that is likely to arise from the inherent difficulties associated with all the techniques examined’.
The study ‘examined the use of give instrumental methods applied to a range of eight very different but industrially-relevant powder pigments’ – four of these ‘are commonly used in the pigment industry’. It was nevertheless the fifth method, electron microscopy, that was found to be the method which ‘probably…comes closest to being able to provide’ the information required, with none of the others being considered suitable for the task. Researchers determined, however, that ‘there are many issues related to sample preparation and counting protocols which need to be resolved and standardised before EM [Electron Microscopy] could provide reasonable comparability’. It was also noted that ‘expertise and knowledge of the specific substance in question is necessary to obtain reliable results’.
The report notes that the aim of the study ‘was not to determine the optimum conditions for every individual sample but rather to produce and evaluate data which could be considered representative of that obtainable in industrial laboratories using existing experimental facilities operated by experienced but not specialised operators’.
Follow this link to read the full report.