S.O.P. No. MLD 055 - Standard Operating Procedure for the Determination
of PM2.5 Mass in Ambient Air by Gravimetric Analysis
This document describes the methodology used by Monitoring and Laboratory Division (MLD) Inorganics Laboratory Section (ILS) staff to analyze the mass of PM2.5 samples collected on Teflon filters.
SUMMARY OF METHOD
Individual Teflon filters (46.2 mm diameter) are weighed on an electronic microbalance before and after field sampling. Particulate matter less than 2.5 um in diameter is collected from ambient air over a 24-hour period. PM2.5 filters are sampled on two different types of samplers: Rupprecht and Patashnick (R&P) (either a single channel or sequential sampler), or Speciation Air Sampling System (SASS™) low-volume sampler. The net difference between pre- and post-sampling filter weights is used to calculate the ambient air mass concentration. After post-weighing, all filters are archived; however, samples from the SASS™ sampler are stored for subsequent analysis.