Fractional Determination of Elemental Carbon and Total Soluble and Insoluble Organic Compounds in Airborne Particulate Matter by Thermal Analysis Combined with Extraction and Heavy Liquid Separation

A thermal method for the fractional determination of elemental carbon (EC) and total soluble and insoluble organic compounds (TSOC and TIOC) in airborne particulate matter has been developed by the optimization of its heating schedule and the pre-separation of other thermal degradable matter. Mixtures of cotton, sucrose or starch as model insoluble organic compounds and carbon black or activated carbon as model EC were subjected to thermogravimetry-differential scanning calorimetry (TG-DSC), and its heating schedule was investigated to separate an exothermic peak of carbon generated from organic compounds from that of EC. The heating schedule with a holding step at 430°C for 60 min gave the best recoveries for such carbonaceous components. Weight losses of 180–485°C and 485–665°C in TG curves were adopted for the determination of TIOC and EC, respectively. In order to determine TSOC and to separate thermal degradable inorganic compounds like sulfate, carbonate and hydroxide, systematic separation consisting of acetone, water and 0.1 M hydrochloric acid extraction and heavy liquid separation of its residue was applied to real samples prior to thermal analysis. The fractions were subjected to TG-DSC; EC and TIOC were successfully determined fractionally.