An automated method for thermal-optical separation of aerosol organic/elemental carbon for 13C analysis at the sub-?gC level: A comprehensive assessment

We describe and thoroughly evaluate a method for 13C analysis in different fractions of carbonaceous aerosols, especially elemental carbon (EC). This combines Sunset thermal-optical analyzer an isotope ratio mass spectrometer (IRMS) via custom-built automated separation, purification, injection system. Organic (OC), EC, other specific from aerosol filter samples can be separated analyzed automatically based on protocols (EUSAAR_2 this study) at sub-?gC levels. The main challenges isolating EC are the possible artifacts during OC/EC including premature loss formation pyrolyzed OC (pOC) that is difficult to separate EC. Since those accompanied with fractionation, their influence stable isotopic composition was comprehensively investigated various test compounds. results show relatively successful separation analysis. further tested real aerosols samples. For biomass-burning source samples, (partial) inclusion pOC into has negligible signature However, ambient significant, if it not well which true many current methods measuring A case study Xi'an, China, where enriched compared shows lead overestimate coal underestimate traffic emissions isotope-based apportionment.