Comparison of supercritical chlorodifluoromethane, nitrous oxide, and carbon dioxide for the extraction of polychlorinated biphenyls and polycyclic aromatic hydrocarbons

Supercritical fluid extraction (SFE) recoveries for native pollutants including PCBs from a standard reference material sediment (SRM 1939), PAHs from a petroleum waste sludge, and PAHs from railroad bed soil were compared using supercritical CHCIF 2 (Freon-22), N 2 O, and CO 2 . While SFE with pure CO 2 yielded the lowest recoveries for each sample, CHCIF 2 consistently yielded the highest extraction efficiencies, most likely because of its high dipole moment