The determination of ozone precursors with a built-in preconcentrator and capillary GC/dual FID
- Varian Chromatography Systems, Walnut Creek, CA (United States)
Title 1 of the Clean Air Act Amendments of 1990 requires cities or air quality districts that are non-compliant with the Ozone National Ambient Air Quality Standard of 120 ppbv to make continuous measurements of targeted ozone precursors. Air samples must be obtained on a one to three hour basis with the requirement that a high percentage of the time interval will be spent in the sample collection process. The preconcentration of the target analytes from these samples by absorbent trapping rather than the traditional use of cryogenic preconcentration on glass beads with liquid nitrogen has been utilized over the past few years for this application. An Ozone Precursor GC system has been configured with a new built-in sample preconcentration trap (SPT) and associated valving capable of preconcentrating a 200 mL air sample. The sample which may be drawn either from a canister or directly from the ambient air first passes through a stripper column for moisture removal and then through an adsorbent trap. The adsorbent trap is cooled to initial conditions with a very small amount of liquid carbon dioxide providing many runs from one cylinder. Following trapping, the precursors are quickly desorbed with the fast heating (40 C/sec) SPT to parallel columns of Alumina Plot and DB-1 for chromatographic separation and quantitation of the trapped analytes. Dual FIDs provide detection. Optimization of the trapping and chromatographic parameters has been performed using a 60 component EPA precursor standard. The results of these studies and a description of the integrated system will be presented.
- OSTI ID:
- 197344
- Report Number(s):
- CONF-9405167-; TRN: IM9612%%118
- Resource Relation:
- Conference: Measurement of toxic and related air pollutants, Durham, NC (United States), 3-6 May 1994; Other Information: PBD: 1994; Related Information: Is Part Of Measurement of toxic and related air pollutants. Proceedings of the 1994 U.S. EPA/A and WMA international symposium; PB: 1075 p.
- Country of Publication:
- United States
- Language:
- English
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