Semivolatile behaviour and filter sampling artifacts for dicarboxylic acids during summer campaigns at three forested sites in Europe

The sampling artifacts for C 2 -C 5 dicarboxylic acids (DCAs) were studied by collecting high-volume PM 2.5 samples using front and back quartz-fibre filters.The filters were analysed for carbonaceous components, and for inorganic cationic and anionic and organic anionic species.Back/front filter ratios were determined for the C 2 -C 5 DCAs, but also for methanesulphonate (MSA -), the various inorganic species, and the carbonaceous components.The sampling artifacts for the inorganic species were small (< 5%) with the exception of those for nitrate.The median back/front filter ratios for MSA -and the C 2 -C 5 DCAs increased in the following order: oxalate (1.5%)-succinate (3%)-MSA -(4%)-malonate (2%-9%)-glutarate (7%-26%).Most of these ratios are smaller than those that were obtained for organic carbon, total carbon, and especially water-soluble organic carbon.Our back/front ratios for the C 2 -C 5 DCAs are lower to much lower than those found in other studies.