Field-based supercritical fluid extraction and immunoassay for determination of PAHs in soils

Abstract

A field-compatible supercritical-fluid extraction (SFE) device and method for extraction of organic contaminants from soil has been developed and combined with field-based immunoassay for on-site PAH (polycyclic aromatic hydrocarbon) determination. The optimised extraction method was tested in field experiments on natural samples with varying water content (0–32% w/w) without any sample pretreatment, yielding an average PAH recovery of 80% versus Soxhlet. The immunoassay functioned in buffer-diluted 10% v/v MeOH SFE extracts, allowing direct determination of PAHs with minimum sample manipulation. Immunoassay served as a reliable semi-quantitative technique for rapid screening of PAHs in SFE preparations of natural samples extracted in the field. Poor performance of the commercial solvent-shake extraction (SSE) method further supported the on-site SFE/immunoassay method.

Keywords:

• Field-based technology
• Environmental risk assessment
• Soil
• Organic contaminants
• Supercritical-fluid extraction
• ELISA

Acknowledgements

The authors gratefully acknowledge European Commission funding of PURE (Protection of Underground Water Resources at Industrially Contaminated Sites, EVK1-CT1999-00030). Thanks are also due to Dan Scott of VHE Ltd., for site access and sample provision.