FIELD-EVALUATION OF THE SFE-INFRARED METHOD FOR TOTAL PETROLEUM HYDROCARBON (TPH) DETERMINATIONS

The determination of total petroleum hydrocarbons (TPH) in contaminated soils using supercritical C02 extraction with quantitation based on infrared spectrometry (SFE-IR) has been compared by performing the SFE-IR measurements in the field and in the laboratory, and by conventional Soxhlet extraction. Generator-powered SFE and infrared instruments were operational only about 20 min after arriving at the sampling locations, and no specialized support vehicle was required. SFE-IR analyses of gasoline-, diesel-, motor-oil-, and crude-oil- contaminated soils yielded virtually identical results (less than 10% variation), whether the samples were extracted and analyzed in the field or in the laboratory. The concentrations of TPH determined using 30-min SFE and 4-h Soxhlet extractions agreed within 20%. Except for the motor-oil-contamined soil, SFE for 10 min yielded 70-95% of the quantity that was extracted after 30 min, indicating that short SFE extractions would be useful for minimizing analysis time for field surveys. © Oxford University Press 1993.