Identification of alkyl dinitrates in ambient air of Central Europe

Bifunctional organic nitrates - organic esters of nitric acid - are part of the pool of components of odd nitrogen (NOY) in the atmosphere. In this pa per, we report the identification of dinitrates in ambient air of Central E urope (Ulm, Germany). The organic nitrates were sampled by adsorptive high volume sampling of 100 m(3) of air with 100 g precleaned silica. Sample pre paration and group separation was performed by NP-HPLC. Separation and dete ction was done by HRGC/EI-MSD. We have extended the identification of dinit rates in ambient air to a number of 30, of which only five have been report ed by other authors before. To our knowledge, this is the first time that 1 3 non-vicinal dinitrates and two branched dinitrates have been identified i n ambient air. Four organic nitrates have never been reported before: the n on-vicinal 1,3-dinitrooxy-pentane (1,3C5), the two branched 2-methyl-1,2-di nitrooxy-propane (2M1,2C3) and 2-methyl-2,3-dinitrooxy-butane (2M2,3C4), an d one diastereomer of 3,4-dinitrooxy-hexane (RR/SS-3,4C6). We are also assi gning the configuration of the two diastereomers of 2,4-dinitrooxy-pentane (2,4C5) found in air before using reference standards obtained by enantiose lective synthesis.