title: Determination of total petroleum hydrocarbons in soil by dynamic on-line supercritical fluid extraction with infrared photometric detection.
abstract: Total petroleum hydrocarbons (TPHs) in soil are determined by on-line dynamic supercritical fluid extraction (SFE) using infrared filter photometry detection. The filter photometer was constructed in the laboratory using a tungsten lamp, an optical notch filter that selects the C-H stretching vibration of the extracted organics, an optical chopper with demodulation electronics, and a PbSe detector. A modified high-pressure fiber optic flow cell was used to couple the SFE system to the photometer. Quantitation of TPHs was accomplished through the construction of calibration curves of integrated absorbance of C-H stretching (over time) versus concentration. Our studies show that the sensitivity of this system is affected by both the optical path length in the high-pressure cell and the SFE fluid flow-rate, and detection limits for TPHs are in the mid part-per-million range. The results of the application of this on-line SFE-IR instrument to the determination of TPHs in real-world samples show good agreement with those obtained from standard Soxhlet extraction-IR methods.
authors.affiliation: Department of Chemistry, Box 9024, University of North Dakota, Grand Forks, ND 58202-9024, USA.
authors.forename: Shijiang
authors.initials: S
authors.lastname: Liang
authors.forename: David C
authors.initials: DC
authors.lastname: Tilotta
mesh_terms: D002138:Calibration; D006838:Hydrocarbons / Q000032:analysis*; D010578:Petroleum / Q000032:analysis*; D012680:Sensitivity and Specificity; D012989:Soil Pollutants / Q000032:analysis*; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D012989:Soil Pollutants