Partition infrared method for total gasoline range organics in water based on solid phase microextraction

A new method is described for determining total gasoline-range organics (TGRO) in water that combines solid-phase microextraction (SPME) and infrared (IR) spectroscopy. In this method, the organic compounds are extracted from 250-mL of water into a small square (3.2 cm x 3.2 cm x 130 mu m thick) of Teflon PFA film. This film, a perfluoroalkoxyethylene polymer, lacks C-H bonds and makes it possible to quantitate the extracted organics directly in it via their C-H stretching vibrations. Three gasoline-range fuels, unleaded gasoline, aviation gas, and lighter fuel (petroleum naphtha), were chosen to evaluate the SPME/ IR procedure. Preliminary experiments show that method detection limits are in the 0.5-1.5 ppm range for spiked solutions, and precision is relatively good (6-11% RSDs). Linear dynamic ranges of calibration extend to the water solubility limits for all fuels studied. Finally, the potential of this SPME/IR method for determining TGRO in natural "real world" water samples was investigated by extracting wastewater contaminated with gasoline. In this procedure, a commercially available gas chromatography standard was used to calibrate the SPME/IR method. The results obtained from the SPME/IR determination of the TGRO in two wastewater samples were in reasonable agreement with those obtained from standard purge-and-trap gas chromatographic analysis.