A novel approach for solid–liquid extraction laser-excited time-resolved Shpolʹskii spectrometry

A new procedure is presented for the analysis of polycyclic aromatic hydrocarbons by solid–liquid extraction (SLE) and laser-excited time-resolved Shpolʹskii spectrometry (LETRSS). Microliters of Shpolʹskii solvent are spiked on the surface of the extraction membrane and LETRSS is directly performed on the organic layer above the surface of the solid substrate. Fluorescence measurements are easily performed with a fiber-optic cell specifically designed for cryogenic measurements at 77 and 4.2 K. In comparison to the SLE–LETRSS procedure previously reported (Environ. Sci. Technol. 35 (2001) 2566), the spiking procedure eliminates the eluting step, reduces solvent consumption and improves limits of detection for at least one order of magnitude.