[Comparison of EC/OC in PM2.5 between filter sampling off-line analysis and in situ on-line measurement]
Min Hu1, Zhi-qiang Deng, Yi Wang
1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China. minhu@pku.edu.cn
Abstract:
Elemental carbon (EC) and organic carbon (OC) in PM2.5 were measured simultaneously at the campus of Peking University from January 2006 to April 2007 by two common used methodologies. One is quartz filter sampling followed by off-line SUNSET Lab EC/OC analyzer and the other is SUNSET in-situ on-line EC/OC analyzer. The comparison shows significant differences on OC measurements between the two methods. The results by filter sampling off-line analysis were as twice high as those by in-situ on-line method. The volatile organic carbons (VOCs) adsorbed by quartz filter led to considerable positive error of OC. The use of parallel plate organic denuder can eliminate such error but cause the evaporation of semi-volatile organic carbon on the filter which induces another negative error of OC, about 10%. The improved method of filter sampling off-line analysis using both parallel plate organic denuder and backup filter has a good agreement with in-situ online measurement.
