FTIR based instrument employing a coiled hollow waveguide cell for rapid field analysis of volatile organic compounds

R. H. Micheels, K. Richardson, D. J. Haan, J. A. Harrington

Research output: Contribution to journalConference article

3 Scopus citations

Abstract

An instrument has been developed which combines a portable Fourier Transform Infrared (FTIR) spectrometer with a hollow waveguide infrared gas cell. This instrument has been applied to the multi-component analysis of 5 volatile organic compounds (VOCs), that are common contaminants in soil. The instrument is designed for rapid field screening of these VOC compounds in soil or water. The instrument employs headspace sampling in small sample vials to measure the VOC content of soil or water samples. The instrument employs either a straight or coiled hollow waveguide gas cell to achieve a long infrared absorption pathlength of 1-2 m with a very low cell volume in the range of 2 to 5 cc. These cell dimensions permit high detection sensitivity along with a rapid system response time. A theoretical model has been developed to predict the infrared light attenuation in the coiled waveguide cell as a function of coil radius and waveguide bore size. Incoherent infrared light transmission losses associated with coiling of waveguides with a 0.197 m coil radius have been found to have an average value of 0.312 dB/m. Calibration experiments have been performed with a series of 5 component VOC gas mixtures with concentrations in the range of 20-200 ppm (volume). Measurements of the partitioning of the VOCs between the soil and gas phase have also been conducted.

Original languageEnglish (US)
Pages (from-to)66-74
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3540
StatePublished - Jan 1 1999

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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