Direct Determination of Isomeric Polycyclic Aromatic Hydrocarbons in Environmental Samples by Conventional and Laser Excited Shpol'Skii Spectroscopy

Various modes of Shpol'skii spectroscopy have been employed to directly determine a number of isomeric four to six-membered ring polycyclic aromatic hydrocarbons (PAHs) in crude extracts of soil and sediment samples with different levels of pollution. The high selectivity of conventional Shpol'skii spectroscopy (lamp excitation-fluorescence and phosphorescence detection) enabled besides several priority PAHs, unambiguous identification of individual monomethylpyrenes, five- and six-membered ring PAH isomers. For a 10 μl sample volume, the absolute limit of detection varied from 0.2 picomole for benzo[e]pyrene (phosphorescence measurements) to 3 femtomole for perylene (lamp excitation/fluorescence detection). Application of laser excited Shpol'skii spectroscopy (LESS) with time-resolved fluorescence detection allowed direct ultra-selective determination of the most potent known to date carcinogen—dibenzo[a,l]pyrene (DB[a,l]P). For this compound, a low 2 femtomole limit of detection (15 percent repeatability) was achieved. DB[a,l]P contents were in the range of tens to hundreds ng/g for different samples.