Application of a quadrupole ion trap time-of-flight mass spectrometer to the analysis of low concentration gas phase organic compounds

A quadrupole ion trap/time-of-flight mass spectrometer (TOF) was developed to make use of the storage capabilities of the ion trap, and the speed and time resolution of a time-of-flight instrument. TOF uses direct air sampling and chemical ionization using O2+ as the reagent. The purpose of this work was to characterize and develop an instrument capable of measuring low concentration gas phase chemicals in the atmosphere, and to demonstrate its abilities in studying isoprene oxidation in a smog chamber. This reaction exemplifies some of the more common tropospheric chemistry for the volatile organic compounds. The results from this experiment were quantified and rate constants for the isoprene products MVK and MACR were obtained. Furthermore, the instrument was able to detect a likely intermediate in the gas-to-particle conversion process.