Comparison of sampling methods for semi-volatile organic carbon associatedwith PM2.5

This study evaluates the influence of denuder sampling methods and filter c ollection media on the measurement of semi-volatile organic carbon (SVOC) a ssociated with PM2.5. Two types of collection media, charcoal (activated ca rbon) and XAD, were used both in diffusion denuders and impregnated back-up filters in two different samplers, the VAPS and the PC-BOSS. The two organ ic diffusion denuders were XAD-coated glass annular denuders and charcoal-i mpregnated cellulose fiber filter (CIF) denuders. In addition, recently dev eloped XAD-impregnated quartz filters were compared to CIF filters as back- up filter collection media. The two denuder types resulted in equivalent me asurement of particulate organic carbon and particle mass. The major differ ence observed between the XAD and charcoal BOSS denuders is the higher effi ciency of charcoal for collection of more volatile carbon. This more volati le carbon does not contribute substantially to the particle mass or SVOC me asured as OC on quartz filters downstream of the denuders. This volatile ca rbon does result in high OC concentrations observed in charcoal filters pla ced behind quartz filters downstream of the SAD denuders and would result i n overestimating the SVOC in that configuration.