Investigations of proton transfer reaction mass spectrometry for applications in organophosphate detection and breath analysis

The reduced electric field dependence of a series of twelve saturated alcohols was investigated with a proton transfer reaction mass spectrometer, PTR-MS. Fragmentation reactions were observed for all but one compound and the dependence of this fragmentation was recorded as a function of reduced electric field. A number of common fragment ions were observed corresponding to carbocations. Effects on the branching ratios from the hollow cathode emission current were also observed and investigated. The reaction of dimethyl methylphosphonate, DMMP in a PTR-MS was studied, along with further chemical weapon simulants. The reaction with DMMP was investigated to explain a product ion at m/z 111. The PTR-MS has been used to demonstrate the possibilities of breath analysis in the diagnosis of liver disease. A promising marker may be limonene, observed on the breath of patients suffering from encephalopathy. Further work would be needed to understand the source of this compound before being used for diagnostic purposes. Data are also reported relevant to the repeatability of a breath sample. The sampling repeatability was calculated for isoprene, acetone, methanol, ethanol and monoterpene. The repeatability for each compound was found to be affected by the intensity of the measured ion and the compound’s solubility.