Multifunctional organic nitrates as constituents in European and US urban photo-smog

Air samples of the atmospheric ground layer in the cities of Ulm in Germany , Las Vegas, Nevada, and Salt Lake City, Utah, in the US were analyzed for organic nitrates. The air samples were taken around noon in summer at sunny weather conditions. 43 (C-6-C-13) alkyl mononitrates, 24 (C-3-C-6) alkyl d initrates, and 19 (C-2-C-6) hydroxy alkyl nitrates have been identified. Th e analytical protocol included high-volume-sampling, NP-HPLC group separati on, high resolution capillary gas chromatography, and detection by the high ly selective mass spectrometer detector (SIM mode, m/z = 46). The levels of the sum of 15 (C-6-C-10) alkyl mononitrates ranged from 2.9 to 11.0 parts per trillion (ppt(v)). The levels of the sum of 21 (C-3-C-6) alkyl dinitrat es ranged from 2.3 to 10.5 ppt(v), and the levels of the sum of 7 (C-2-C-4) hydroxy alkyl nitrates ranged from 7.3 to 28 ppt(v), respectively, in the urban air samples. These results emphazise the contribution of the alkyl di nitrates and hydroxy alkyl nitrates besides the alkyl mononitrates to the b udget of NOY compounds. No major differences in levels and pattern of the o rganic nitrates are present in air of the German and the US cities.