Shpolʹskii spectroscopy as a tool in environmental analysis for amino- and nitro-substituted polycyclic aromatic hydrocarbons: A critical evaluation

Aiming at the development of an alternative isomer-specific spectral method favourable for identification of mutagenic amino- and nitro-substituted polycyclic aromatic hydrocarbons (PAHs) in environmental samples, the possibility to utilize Shpolʹskii spectroscopy, a high-resolution cryogenic molecular luminescence technique, is critically investigated. New data representing specific, vibrationally resolved cryogenic fluorescence and phosphorescence spectra of a number of individual amino-substituted naphthalenes, anthracenes and fluorenes are presented in addition to spectra of four- and five-membered ring amino-PAHs reported earlier. Room temperature fluorescence, photostability of the amino-PAHs and the influence of the cooling rate on spectral quality are considered. For determination of the nitro-PAHs, an off-line chemical reduction with zinc powder was optimized to convert these non-fluorescent compounds to the corresponding aromatic amines. Furthermore, the Shpolʹskii technique was successfully applied to a mixture of certified standard reference materials (SRM 1587 and SRM 1647), containing a range of parent and nitro-PAHs. Finally, in combination with normal-phase liquid Chromatographic separation, the methods developed enabled the determination of 1-nitropyrene in a diesel paniculate SRM 1650.