SCREENING OF POLYCYCLIC AROMATIC-HYDROCARBONS IN SOIL BY ONLINE FIBER-OPTIC-INTERFACED SUPERCRITICAL-FLUID EXTRACTION SPECTROFLUOROMETRY

An interface for spectrofluorometric measurements in the supercritical (SC) CO2 emerging from the extraction cell of a supercritical fluid e xtractor prior to depressurization was developed. The windowless now c ell designed for this purpose is furnished with an inlet and outlet fo r the SC-CO2 stream; it can withstand pressures up to at least 350 bar and is connected to the light source and detector by means of two fib er-optic cables. The combined system allows the real-time on-line fluo rometric monitoring of the supercritical fluid extraction (SFE) proces s and provides qualitative and semiquantitative information from super critical extracts of real and spiked samples. The determination of fiv e polycyclic aromatic hydrocarbons (PAHs) in spiked soil by SFE with o n-line fluorescence detection provided relative standard deviations le ss than 5%, as well as benzo[k]fluoranthene recoveries from several sp iked soils between 93 and 107%, with an RSD less than 10%. Also, cryse ne-benzo[a]anthracene binary mixtures in spiked soil were resolved wit h recoveries of 89-103% and an RSD of about 10%. The use of the propos ed equipment for screening real soil samples for PAHs using on-line SF E spectrofluorometry is demonstrated.