Analysis of Polynuclear Aromatic Hydrocarbon Mixtures Desorbed from Particulate Matter in a Low-Temperature Matrix by Shpol'skii Time-Resolved Fluorescence Spectroscopy

A simple approach for analyzing mixtures of polynuclear aromatic hydrocarbons (PAH) desorbed from particulate matter that does not involve any separations was studied with the use of anthracene, pyrene, and fluoranthene as model compounds. PAH absorbed on alumina was vaporized at elevated temperature in a sample cell and mixed with vapor-phase n-hexane in a stream of helium carrier gas. This gaseous mixture flowed through a nozzle into a vacuum chamber and was condensed onto a cold finger at 77 K to form a Shpol'skii matrix. In the time-resolved fluorescence emission spectra obtained for this low-temperature matrix, selectivity is improved relative to room-temperature studies. If the excitation wavelength of the source is changed, the identification of PAH in mixtures was further improved. The detection limits were less than 10 ng for pyrene and anthracene and 100 ng for fluoranthene, with 337.1-nm excitation.