Characterisation of polycyclic aromatic hydrocarbons in liquid products from pyrolysis of Eucalyptus grandis by supercritical fluid extraction and GC/MS determination

Slow pyrolysis of Eucalyptus grandis wood was performed in an oven laboratory and liquid products were quantitatively collected. Polycyclic aromatic hydrocarbons (PAHs) content was obtained by partitioning the pyrolysis liquid products with supercritical CO2 extraction followed by GC/MS analysis. The SFE procedures were validated by comparing the PAH content with those obtained by means of adsorption column chromatography. While extracted amounts lower than 100 mu g/g could be obtained by using the column chromatography fractionation procedures at 80 degrees C, the SFE procedures were able to extract, at 100 and 371 bar, respectively, 17.2 and 69.3% (w/w) based on the initial mass of the anhydrous sample. In the pressure range from 100 to 371 bar, increasing the pressure increases the extraction yields obtained. However, the PAHs showed a different behaviour in the same pressure range. The lighter PAHs with molecular weight up to 192 were most successfully extracted at 100 bar. On the other hand, the PAHs with molecular weight from 202 to 278 were better recovered by SFE at 371 bar. (C) 1998 Elsevier Science Ltd. AII rights reserved.