Positive ion chemistry in the exhaust plumes of an air craft jet engine and a burner: investigations with a quadrupole ion trap mass spectrometer

Using a quadrupole ion trap mass spectrometer detailed composition analysis were made of positive ions in the exhaust of an air craft jet engine and o f a jet fuel burner. For both scenarios complex organic ions with large mas s numbers were most abundant. By employing the MS2-mode of the quadrupole i on trap mass spectrometer mass selected trapped ions were intendently broke n up and characteristic fragment ions were observed. The latter indicate th at the parent ions contain hydrogen, carbon and oxygen which is indicative of oxygenated hydrocarbons. This contrasts recent composition measurements of negative ions in air craft jet engine exhaust made by our group which re vealed that negative ions contain the inorganic acid H2SO4. Our present mea surements support the view that positive ions in air craft jet engine exhau st contain preferably organic molecules. (C) 2000 Elsevier Science Ltd. All rights reserved.