Micelle formation for improvement of continuous subcritical water extraction of polycyclic aromatic hydrocarbons in soil prior to high-performance liquid chromatography-fluorescence detection

A new method for the extraction-individual separation-determination of poly cyclic aromatic hydrocarbons (PAHs) in soil is reported. The method is base d on the integration of three steps: continuous subcritical extraction, sol id-phase clean-up I preconcentration, and HPLC separation with post-column fluorimetric determination. Sodium dodecyl sulfate (SDS) was added to the w ater for favouring the extractability of the low-polarity analytes. Soil sa mples spiked with the target PAHs were subjected to static-dynamic extracti on with SDS-water at 50 bar, 150 degreesC, for 15 min of static extraction and 10 min dynamic extraction at a how-rate of 3 ml/min. Recoveries from 73 .6 to 110.4% were obtained in the presence of SDS versus 30 to 80% obtained with water as extractant. The calibration graphs provided by HPLC-fluorime tric detection were run between 0.031 and 0.375 mug/ml for each analyte wit h regression coefficients between 0.917 and 0.999 and precision, expressed as RSD, between 1.2 and 11.5%. The method was applied to a certified refere nce material [CRM 524, BCR (Community Bureau of Reference), industrial soil /organic] for validation and the results obtained were in agreement with th e certified values. (C) 2000 Elsevier Science B.V. All rights reserved.