City centre concentrations of polycyclic aromatic hydrocarbons using supercritical fluid extraction

A method has been developed to allow routine quantitative analysis of polycyclic aromatic hydrocarbons (PAH) in urban dust particulates with a 12 h sampling time. Supercritical CO2 with polar modifier was used for extraction from sampling media and subsequent sample clean-up and analysis was performed using on-line HPLC-GC. Recoveries of PAH from a NIST certified urban dust sample SRM1649 were comparable with those quoted by NIST. A sample of data from three continuous monitoring programs of particulate phase PAH is presented along with accompanying results from ambient gas analysis of NOx, SO2, O3, and CO. One sampling period includes a meteorological temperature inversion, when PAH levels rose to 6–7 times their mean values. Pearson correlation coefficients have been calculated to test for correlations between PAH levels and other atmospheric pollutants. The PAH show a very strong correlation within a given ring group and strong correlation between ring groups. The temporal variations of the PAH are also quite closely correlated with NOx and CO.