DIRECT ANALYSIS OF POLYCYCLIC AROMATIC-HYDROCARBONS IN CLOUD-AFTER AEROSOL FILTRATES USING LASER-DESORPTION MASS-SPECTROMETRY

A novel technique for the rapid screening of polyaromatic hydrocarbons (PAHs) in atmospheric particulates is presented Two-step laser desorp tion laser photoionisation time-of-flight mass spectrometry was used t o assay for PAHs in cloud-water particulates collected near Peebles in southern Scotland. The particulates were examined in situ on their ho st filters removing the requirement for time-consuming sample extracti on and separation. The mass spectra obtained from a single filter are shown. The principal components of these are assigned to PAH contamina nts and phthalate contaminants. A distribution of PAHs was observed us ing 193 nm laser photoionisation. The mass spectrum obtained on using 248 nm laser photoionisation exhibits a different intensity distributi on demonstrating an ionisation wavelength dependence. The utility of t he technique for rapid screening of PAHs and other polyaromatic specie s is discussed.