Field-portable determination of polychlorinated biphenyls and polynuclear aromatic hydrocarbons in soil using supercritical fluid extraction

Abstract

A single SFE method for field extraction of PCBs and PAHs in soils was developed for use in combination with capillary GC-ECD or FID without the need for cleanup steps after extraction. The method involves 20-min extractions using pure CO 2 at 150°C and 400 bar. GC analysis was performed with 15-min (PCBs) or 22-min (PAHs) temperature programs. The final analytical method was demonstrated in field experiments (with the use of portable power sources) at different waste sites and was shown to give results in excellent agreement with conventional laboratory Soxhlet extraction. The practical determination limits of the method (as concentrations of the 5-g soil samples) without any concentration or cleanup of the SFE extracts was 2≈200 ppb of individual PAHs and 2≈10 ppb of individual PCBs (2≈100 ppb of total PCB as Aroclor 1260) Since the SFE collection solvent was acetone, the extracts were compatible with enzyme-linked immuno-sorbent assay (ELISA). ELISA and GC-ECD determinations of PCBs as total Aroclors agreed within 2≈50% when ELISA was performed in the laboratory. However, ELISA failed to yield useable results when performed outdoors under field conditions.