Development of aromatic compounds of urban aerosols in the course of a 24-hour period - A study using two-step laser mass spectrometry

Laser desorption/laser photoionization mass spectrometry (two-step laser ma ss spectrometry, L2MS) is a powerful tool for the selective analysis of par ticle-bound organic compounds. After infrared laser-induced thermal desorpt ion, the analytes are photoionized by an ultraviolet laser pulse. The ions are then mass separated and detected in a time-of-flight mass spectrometer. The main feature of this analytical method is an excellent sensitivity, al lowing the direct analysis of very small quantities of particles collected on a filter. This allowed us to follow the temporal development of selected polycyclic aromatic hydrocarbons on urban aerosol samples with only 15 min utes time resolution. Data obtained over the course of one day in February 1998 is presented. The temporal behavior was found to be quite different fo r different mass spectral peaks, which may be due to different emission sou rces.