Development of a gas chromatograph for trace level measurement of peroxyacetyl nitrate (PAN) using chemical amplification.

摘要

eroxyacetyl nitrate (PAN) is a secondary atmospheric pollutant which plays an important role in the tropospheric distribution of ozone. In order to evaluate the global importance of PAN, improvements in ultra-trace measurements in remote areas are necessary. This project involved the development of a gas chromatographic technique for trace level detection of Peroxyacetyl Nitrate (PAN) that relies on post-column chemical amplification as a means of improving the detection limit. The GC detector is based on luminol chemiluminescence detection of NO;The system operates at optimized carrier gas NO and CO concentrations of 6 ppm and 8% respectively, using a 2 cm i.d. Pyrex post-column reactor. Under these conditions, the experimentally determined chain length (NO;The instrument was found to exhibit a non-linear response to PAN concentrations, in the range 0.05-3 ppb, based on comparison with a GC-ECD, attributed to the non-linearity of the luminol detector. The chemical amplification GC was first compared against a series of ambient air PAN measurements conducted using a GC-ECD instrument in November 1991 in Toronto, and subsequently in December 1992 at a rural Ontario site. The latter campaign indicated that for ambient PAN concentrations ranging between