Carbon compound specific stable isotope analysis (CSIA) of polycyclic aromatic hydrocarbons (PAH) in air particulate matter (PM) for source apportionment

Compound specific isotopic ratio is performed by using a gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS). Polycyclic aromatic hydrocarbons (PAHs) find their origin in different processes and are present in particles polluting air as particulate matter. The different sources of PAHs hypothetically result in different carbon isotopic ratios (13C/12C) in these compounds. Hence analysis of this ratio potentially links pollution to source, allowing source apportionment. Two capillary columns (AT-5ms and AT-50ms) for separation of polycyclic aromatic hydrocarbons (PAHs) in certified reference materials: BCR-fluoranthene, BCR-pyrene and reference mixtures certified for concentrations: EPA16 PAHs and SRM 2260a are compared in this report. On this ground the compound specific isotopic measurement method (CSIA) for carbon isotopes in PAHs was developed. The method was tested on samples provided within the JRC-IES Krakow Integrated Methodology Project on Emissions and Health. The measurements show that the required concentration for CSIA measurement is 5-10 ng/μl per each PAH for precision 0.5 ‰ (δ13C). It was not possible to measure PAHs in Krakow samples due to the low concentration of PAHs of 0.03 to 1 ng/μl and the presence of interfering compounds. For CSIA measurements of PAHs extracted from particulate matter sample clean up is necessary to eliminate aliphatic hydrocarbons and other interfering compounds co-extracted with PAHs.