The growing requirement for laboratory accreditation and improved production control led to a demand for traceability to the international standards of length and mass of measurements made with aerosol and powder analysis equipment. This is particularly true for instruments based on optical techniques since currently available reference materials are irregular in shape and insufficiently defined in terms of their shape/optical properties to give unambiguous results. The new polydispersed certified reference materials being produced will remedy these deficiencies as they are spherical particles of known densities, refractive indices and porosity. The 14 materials cover 6 one decade size ranges between 0.1 and 650 mm, all distributions being unimodal and log-normal. For each size range materials with at least two different optical properties (transparent, opaque or coloured) will be available. Dependent upon size range, the materials will be certified by a combination of at least 3 of the following six methods: sieving , gravitational sedimentation, centrifugal sedimentation, optical microscopy, electron microscopy and electrozone analysis. The first three methods are traceable in terms of mass, the next two in terms of length and the last one in terms of both length and mass. The first materials will be certified in mid-1995.
Funding SchemeCSC - Cost-sharing contracts
CH3 7PB Chester