Articles | Volume 7, issue 12
Atmos. Meas. Tech., 7, 4431–4444, 2014
Atmos. Meas. Tech., 7, 4431–4444, 2014
Research article
12 Dec 2014
Research article | 12 Dec 2014

Development of an automated high-temperature valveless injection system for online gas chromatography

N. M. Kreisberg1, D. R. Worton1,2, Y. Zhao2,*, G. Isaacman2, A. H. Goldstein2,3, and S. V. Hering1 N. M. Kreisberg et al.
  • 1Aerosol Dynamics Inc., Berkeley, CA, USA
  • 2Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA
  • 3Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA
  • *now at: Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA

Abstract. A reliable method of sample introduction is presented for online gas chromatography with a special application to in situ field portable atmospheric sampling instruments. A traditional multi-port valve is replaced with a valveless sample introduction interface that offers the advantage of long-term reliability and stable sample transfer efficiency. An engineering design model is presented and tested that allows customizing this pressure-switching-based device for other applications. Flow model accuracy is within measurement accuracy (1%) when parameters are tuned for an ambient-pressure detector and 15% accurate when applied to a vacuum-based detector. Laboratory comparisons made between the two methods of sample introduction using a thermal desorption aerosol gas chromatograph (TAG) show that the new interface has approximately 3 times greater reproducibility maintained over the equivalent of a week of continuous sampling. Field performance results for two versions of the valveless interface used in the in situ instrument demonstrate typically less than 2% week−1 response trending and a zero failure rate during field deployments ranging up to 4 weeks of continuous sampling. Extension of the valveless interface to dual collection cells is presented with less than 3% cell-to-cell carryover.