Determination of organic and elemental carbon in atmospheric aerosol samples by thermal evolution

Abstract

A simple apparatus is described for determination of volatile organic and elemental carbon fractions in filter-collected atmospheric aerosol samples. The two-step technique involves rapid heating and thermoevolution of organic carbon at 400/sup 0/C in helium carrier gas, followed by removal of elemental carbon at 700/sup 0/C in 10% O/sub 2//He. Evolved carbon is converted to CO/sub 2/ on copper oxide catalyst, purified, and analyzed by nondispersive infrared (NDIR) spectrometry. Flash heating of ambient aerosol samples minimizes organic-to-elemental carbon conversion, allowing determination of organic and elemental carbon fractions with relative standard deviations of +/-8% and +/-12%, respectively, for total carbon loadings of 6-50 ..mu..g of C/cm/sup 2/ filter area. Blank filter variability, sample heating duration, and the effects of sample heating rates and pyrolysis temperature are evaluated. Ambient aerosol carbon data from both urban and remote sampling sites are presented and discussed.