HPLC combined with multiple mass spectrometry (MSn): an alternative for the structure elucidation of compounds and artefacts found in smog chamber samples

Ion trap multiple mass spectrometry combined with high-performance liquid c hromatography (online HPLC-MSn) was used to identify carbonyl compounds and artefacts found in air samples of 2-3 L taken during the OH-radical reacti on study of cis-3-acetyl-2,2-dimethylcyclobutylethanal (pinonal) or cis-3-a cetyl-2,2-dimethylcyclobutylcarbaldehyde (nor-pinonal) in a smog chamber. C arbonyls were transformed into 2,4-dinitrophenylhydrazones. Detection of lo w picogram quantities was possible. Twenty-eight compounds could be identif ied based on the presence of structure characteristic fragments, a develope d fragmentation scheme, comparison of retention times and a library of MSn spectra of selected carbonyls. Furthermore, the additional elucidation of t he sub-structures of sixteen unknowns was possible. Details about the struc ture elucidation procedure and the formation of the observed fragments are presented.