Proton transfer reaction mass spectrometric investigations of compounds of relevance to homeland security and breath analysis

The work in this thesis presents a series of investigations of ion/molecule processes taking place in the reaction region of a proton transfer reaction mass spectrometer (PTR-MS) for the analytical detection of a series of compounds of relevance to homeland security and health sciences. These compounds include for homeland security applications illicit drugs and related compounds, TNT, mono and di- nitrotoluenes, nitroanilines, and for the health sciences ketones, anaesthetics and phthalates. The results of quantum chemical calculations are also presented, which have been used to aid in the interpretation of the experimental results. The calculations include the proton affinities and gas-phase basicities of many of the neutral molecules and the energetics of some key ion/molecule reaction pathways. A key objective is to present work which has improved the selectivity of PTR-MS through the manipulation of the ion chemistry or through fast pre-separation techniques. These have resulted in the PTR-MS becoming a multi-dimensional analytical technique.