4. Conclusions
A simple and sensitive analytical method with HPLC–FDL is proposed to determine the OH–PAHs, 1–hydroxypyrene (1–OHPYR) and 2–hydroxyphenantrene (2–OHPH) in concentrations of the order of pg m–3, applicable to the analysis of atmospheric aerosol samples. Monitoring of airborne samples collected in Madrid over an entire year indicated the levels of these compounds varied from 1.7 pg m–3 to 244.1 pg m–3, showing clear seasonal behavior. Using several statistical tools, this behavior was confirmed and correlations identified between 2–OHPH and 1–OHPYR concen– trations and those of chemical factors, mainly nitrogen and sulfur oxides, involved in photochemical reactions. In contrast, as temperature and solar radiation rise, ozone levels also increase reducing the OH–PAHs levels.