Air Particulate Matter on Filter Media

This Reference Material (RM) 8785 is intended primarily for use in the evaluation of analytical methods used to characterize the carbon composition of atmospheric fine-particulate matter (PM) for national air quality monitoring programs.

This RM consists of only the fine fraction (nominally < 2.5 µm aerodynamic diameter) of SRM 1649a Urban Dust resuspended in air and filtered onto quartz-fiber filter.

RM 8785 also provides the atmospheric chemistry and ocean-sciences community with a means to inter-compare methods and laboratories for the measurement of elemental (black) carbon.

RM 8785 has value-assignments for total carbon, elemental carbon and organic carbon measured according to two thermal-optical methods: the NIOSH and IMPROVE protocols.

A unit of RM 8785 consists of three loaded filters, each uniquely identified by its APM identification number (e.g., APM 1257), its production characteristics, i.e., batch and chamber-column-row (e.g., 12959-30 and IV-D-5, respectively) and its mass of fine SRM 1649a on the filter (e.g., 1948 µg).

For the most part, filters contained in each unit were randomly selected from the population of 2231 filters (Table 1; see Appendix); however, if all three filters selected per unit had a loading nominally less than (or greater than) the 50th percentile, then the next available filter in the greater than (or less than) 50th percentile was substituted for one of the three original filters.

Therefore, the expectation is that each unit represents at least one filter from the lower 50th percentile and one filter from the upper 50th percentile; however, this distribution cannot be guaranteed due to uncertainties in the packaging process.

A filter (process) blank is available as RM 8786.

Manufacturer: NIST ( National Institute of Standards and Technology)