The optimization of sample clean-up for the analysis of air particulate matter PAHs' stable carbon isotope ratio
using Solid Phase Extraction (SPE) cartridges is described in this paper. Various adsorbents, such as silica gel, alumina,
and florisil, commercially available for sample purification were compared. Best performance for the cleanup
of 24-h air particulate matter samples was obtained with activated silica-gel columns in terms of selectivity
and reproducibility. One step clean-up was optimized for concentration determination and in case of coelutions,
a second stepwas additionally used for carbon isotope ratio analysis. The methodwas subsequently validatedwith
standard reference material andwas checked for carbon isotope fractionation artifacts. No significant
differences in δ13C values were found for unprocessed solution of PAHs and solution subjected to the extraction
and purification procedure. The procedure was tested on air particulate matter samples collected in three different
locations in Belgium. Statistically significant differences in carbon isotope ratio of PAHs between Borgerhout
location and Zelzate or Gent were noticed, confirming the differences in distribution and diagnostic ratios found
during the concentration analyses and different PAH sources in these locations. The results, therefore, seemvery
promising for the use of δ13C of PAHs as an additional information helpful in source identification of these
pollutants