CAPILLARY GAS-CHROMATOGRAPHIC ANALYSIS OF NITROGEN-DIOXIDE AND PANS WITH LUMINOL CHEMILUMINESCENT DETECTION

Peroxyacyl nitrates (PANs) and nitrogen dioxide are important atmosphe ric air pollutants in the troposphere. These atmospheric nitrogen spec ies are strongly coupled chemically by a clearly temperature-dependent equilibrium in the troposphere. A chemical method that can measure bo th nitrogen dioxide and PANs rapidly and with sub-part-per-billion det ection is described that is based upon a modified luminol detection sy stem coupled to a capillary gas chromatographic column by using helium as a carrier. The system can readily separate and detect nitrogen dio xide, peroxyacetyl nitrate, peroxyproprionyl nitrate, and peroxybutyrl nitrate with detection limits in the low tens of parts per trillion w ith total analysis time of less than 1 min. Calibration of PAN by ther mal decomposition to nitrogen dioxide is demonstrated with PAN detecti on sensitivities approximately 75% of the sensitivities observed for N O2 luminol detection by using helium as a carrier gas. The advantages of this method for simultaneous measurement of nitrogen dioxide and PA Ns over ozone chemiluminescent detection and electron capture detectio n are discussed, as well as potential applications of this method for heterogeneous surface chemistry studies of PANS and nitrogen dioxide a nd for tropospheric measurements. (C) 1998 Elsevier Science Ltd. All r ights reserved.