Comparison of supercritical fluids and enhanced-fluidity liquids for the extraction of phenolic pollutants from house dust

The supercritical fluid extraction (SFE) of polar analytes and/or complex and adsorptive matrices is often difficult. The use of enhanced-fluidity liquid extraction (EFLE) as an alternative is investigated herein, Enhanced-fluidity liquids are prepared by combining a large proportion of an associated organic solvent with a low-viscosity liquid, such as CO2. The extraction of 11 phenolic and nitroaromatic pollutants from house dust was tested with Soxhlet extraction, SFE, and EFLE. The addition of methanol to CO2 greatly improved the extraction rate compared to CO2 alone, A 20/80 mol % methanol/CO2 mixture at enhanced-fluidity liquid conditions yielded statistics higher recoveries than other methanol/CO2 mixtures for the majority of analytes. Enhanced-fluidity liquid methanol/H2O/CO2 mixtures showed gains in extraction yields relative to methanol/CO2 mixtures. For example, recoveries of all 11 analytes averaged 50% with 10/90 mol % methanol/CO2, 61% with 20/80 mol % methanol/CO2, and 69% with 32.1/7.9/60.0 mol % methanol/H2O/CO2. The addition of methanol or H2O directly to the sample as static modifier was also tested; methanol yielded higher recoveries, although the results were 10-20% lower than those obtained with methanol/CO2 and methanol/H2O/ CO2 mixtures, Recoveries by SFE and EFLE at various conditions were comparable to or better than Soxhlet extraction for all of the analytes studied.