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The primary crystallite size of titania powder relates to its properties in a number of applications. Transmission electron microscopy was used in this interlaboratory comparison (ILC) to measure primary crystallite size and shape distributions for a commercial aggregated titania powder. Data of four size descriptors and two shape descriptors were evaluated across nine laboratories. Data repeatability and reproducibility was evaluated by analysis of variance. One-third of the laboratory pairs had similar size descriptor data, but 83% of the pairs had similar aspect ratio data. Scale descriptor distributions were generally unimodal and were well-described by lognormal reference models. Shape descriptor distributions were multi-modal but data visualization plots demonstrated that the Weibull distribution was preferred to the normal distribution. For the equivalent circular diameter size descriptor, measurement uncertainties of the lognormal distribution scale and width parameters were 9.5% and 22%, respectively. For the aspect ratio shape descriptor, the measurement uncertainties of the Weibull distribution scale and width parameters were 7.0% and 26%, respectively. Both measurement uncertainty estimates and data visualizations should be used to analyze size and shape distributions of particles on the nanoscale.
Declining European natural gas resources and increasing legislation mean that diversification towards ‘non-conventional gases’ is essential. Accurate and traceable measurements of the composition of non- conventional gases are required to ensure gases can be transported in existing pipeline networks, and used with existing appliances. The EMRP ‘Characterisation of energy gases’ project is successfully developing a metrology infrastructure to underpin these measurements. New standards and methods have been developed for biogas composition, biogas impurities, coal mine gases, refinery gases and environmentally-friendly odorants. The project is set to conclude in 2013 with the challenging analysis of a series of real non-conventional gas samples.