Experimental design approach for the optimization of supercritical fluid extraction of chlorophenols from polluted soils.

Supercritical fluid extraction and liquid chromatography-electrochemical detection (LC-ECD) were used to the determination of chlorophenols in contaminated soil samples. Full factorial design experiments were used in order to optimize the extraction parameters: pressure, extraction cell temperature and percentage of modifier. Pressure and percentage of modifier (methanol) had statistically significant effects on the recovery of the chlorophenols. Good repeatability (4.9-11.8%) and reproducibility (4.9-12.5%) were achieved and low detection limits (3-150 ng g-1) were obtained. The method was validated by comparing the results with those obtained in a European intercomparison exercise.