AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Using Aluminum Foil Impaction Substrates for Elemental Analysis of Airborne Particulate Matter Samples
WEI XUE, Jian Xue, Peter Green, Michael Kleeman, University of California, Davis
Abstract Number: 598 Working Group: Instrumentation and Methods
Abstract Aluminum foil substrates and Teflon filters are the two main substrates for airborne particulate matter (PM) collection using Micro-Orifice Uniform Deposition Impactors (MOUDIs). Samples collected on foil substrates are analyzed for carbonaceous compounds while Teflon samples for ions and elements. The Teflon filters typically cost 10 times more than the foil substrates, so a method that could serve both desired chemical analyses from a single MOUDI instead of two would improve our ability to characterize regional trends of PM0.1 and other size fractions.
In this work we examine the feasibility of performing elemental analysis of PM samples collected foil substrates in MOUDIs. The PM extraction method developed at UC Davis for Teflon filters (sonication in a mixture of 75% acetone and 25% nitric acid followed by nitrogen evaporation of acetone) was modified by sonicating foil samples in pure acetone and then transferring them to a second vial where they are mixed with nitric acid. The original foil substrates are exposed to the acetone / nitric acid mixture for only a brief time to avoid excessive dissolution of the aluminum substrate. Acetone is then evaporated with nitrogen and analysis is conducted with ICPMS.
Two collocated MOUDIs - loaded with Teflon filters and foil substrates, respectively - were used to test the efficiency of the new method. Results showed that Teflon and foil gave similar PM size distributions for elements of interest. The modified method was able to measure 80% of the total mass of all elements of interest, suggesting that an extraction efficiency correction may be needed. The method detection limits of the foil method are similar to the Teflon method for most of the elements of interest, except for vanadium, gallium, thallium and lead. This study suggests feasibility of using a single MOUDI loaded with foil substrates for sampling networks.