Extraction and Recovery of Organic Pollutants from Environmental Solids and Tenax-GC Using Supercritical CO2

Abstract

The use of supercritical CO₂ extractions to yield rapid and quantitative recovery of polycyclic aromatic hydrocarbons (PAHs) from both solid samples and Tenax-GC sorbent traps is described. Supercritical CO₂ extractions of National Bureau of Standards SRM1650 (diesel exhaust particulate) with and without 5% methanol modifier yielded quantitative recovery of the PAHs with extraction times as short as 30 min. Quantitative analysis of the extracted PAHs using gas chromatography/mass spectrometry (GC/MS) gave excellent agreement with certified values. Class-specific extractions of alkanes and PAHs from diesel exhaust particulates were also obtained by varying extraction pressures. Supercritical CO₂ extraction of Tenax-GC sorbent traps were shown to give satisfactory blanks and quantitative recovery of PAHs as large as coronene (molecular weight = 300) at low temperatures (45°C). Finally, direct coupling of the supercritical fluid extraction step with on-column cryogenic trapping in a gas chromatographic column (analogous to thermal desorption/cryogenic trapping techniques) is demonstrated.