(Laser-excited) Shpol'skii fluorometry: applications in marine environmental analysis of polynuclear aromatic hydrocarbons

Abstract

Shpol'skii spectroscopy is a technique that can be employed to obtain highly resolved spectral signatures of molecules. The high-resolution spectra are obtained by using n-alkanes as solvents that form neat crystalline matrices at low temperatures. The specificity and sensitivity of the Shpol'skii method can be further improved by application of selective laser excitation. Summarizing, Shpol'skii spectra show the highly specific fingerprinting properties of IR spectra, but at the same time have the inherently high sensitivity of fluorescence techniques. In this paper attention will be given to principles and general experimental aspects of the Shpol'skii technique. Furthermore, some applications in environmental analysis will be discussed in more detail: (1) the qualitative determination of polycyclic aromatic hydrocarbons (PAH) in suspended matter collected in estuarine water; (2) the quantitative determination of PAH in NRCC sediment reference material SES-1; and (3) the application of laser-excited Shpol'skii spectroscopy for the qualitative determination of PAH in crude extracts of biotic samples. It is shown that the Shpol'skii technique can be used successfully as an independent reference method for both qualitative and quantitative checks of conventionally used determination methods. Because of the high selectivity of the low-temperature method, PAH can be quantitatively determined without any sample clean-up, even in extremely complex biotic samples.