EXAMINATION OF A PROCEDURE FOR THE PRODUCTION OF A SIMULATED FILTER-BASED AIR PARTICULATE MATTER REFERENCE MATERIAL

An approach for producing simulated air particulate matter (APM) depos ited on filters has been developed and investigated as to its usefulne ss for yielding large batches of filters as a future reference materia l. The APM deposited on the filters was a material collected from an u rban industrial area, and had been milled to approximate a material of PM-2.5 particle size distribution. The milled APM material was loaded onto filter substrates (Nuclepore) through the deposition of aliquots from a liquid suspension via vacuum filtration. It should be noted th at these filters do not represent a typical PM-2.5 elemental compositi on, since the milling increased the proportion of crustal materials an d the suspension in liquid decreased the sulfate content. Homogeneity between filters was tested using INAA (whole filter analysis) and ED-X RF and PIXE and was estimated to be in the 5% range (relative standard deviation). Homogeneity within the filters and among the filters was also tested using micro-XRF and found to be acceptable for the element s tested. The results of the tests carried out on the filters indicate that this approach is appropriate for large-scale production of simil ar filters for distribution as reference materials.