HIGH-SPEED SUPERCRITICAL-FLUID EXTRACTION METHOD FOR ROUTINE MEASUREMENT OF POLYCYCLIC AROMATIC-HYDROCARBONS IN ENVIRONMENTAL SOILS WITH DICHLOROMETHANE AS A STATIC MODIFIER

Supercritical fluid extraction (SFE) modified for the high-speed and efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from polluted soil samples was evaluated and shown to be usable in a routine setting. On starting SFE, a small amount of dichloromethane is added to a chemically dried and cryogenic-ground soil sample. The SFE extract is collected within 15-20 min and the PAHs are determined by HPLC equipped with fluorescence and UV detectors. Within-day and day-to-day reproducibilities were comparable to those obtained after a 4-h sample preparation including liquid-liquid extraction. A good correlation was found between the PAH concentrations measured after modified SFE and liquid-liquid extraction. Recoveries of samples spiked with PAHs were of the order of 100%. In two samples used in a quality control programme, PAH concentrations were similar to those obtained by eleven other laboratories. The modified SFE procedure fulfils the requirements of rapidity, high extraction efficiency and simple performance.