Accelerated solvent extraction of phenols from soil

Abstract

Accelerated solvent extraction (ASE) has been investigated as a method of sample preparation in environmental analysis. Using an experimental design approach the influence of operating variables (pressure, temperature and extraction time) on the recovery of seven phenols that have been slurry spiked on soil has been investigated. In every case, except 2-methylphenol, no variables were found to be significant within the limits investigated (pressure, 4–20 MPa; temperature, 30–70 °C; and extraction time, 5–25 min). ASE was compared with shake-flask extraction and found to give similar recoveries. The exception was 2,4-dimethylphenol which was not recovered by the shake-flask approach and was only poorly recovered using ASE (mean recovery, 24.5% with an RSD of 17.6%, based on 15 individual determinations). For shake-flask extraction the mean recoveries ranged from 70.3 to 116.1% with RSDs of 6.5 to 27.2% compared to ASE which gave mean recoveries from 73.8 to 90.2% and RSDs between 8.7 and 21.1%. It is expected that improvements in precision would be obtained using an automated ASE system. A cleaner UV chromatogram was obtained from the ASE extract. The feasibility of ASE in environmental analysis is demonstrated.