PNNL

Abstract

Volatile organic compounds (VOCs) can be monitored by proton transfer reaction (PTR) MS, in which a PTR drift tube is coupled to a quadrupole mass spectrometer. In this technique, compounds undergo proton transfer reactions when they collide with H3O? ions. This soft chemical ionization method, which results in little fragmentation, allows researchers to detect trace levels of VOCs from relatively uncomplicated spectra. Sometimes, the m/z values of VOCs are similar or identical, rendering it impossible to make a positive identification. Thus, Michael Alexander and co-workers at the Pacific Northwest National Laboratory, San Francisco State University, and Innsbruck University (Austria) developed a novel instrument that couples a PTR drift tube to an ion trap mass spectrometer, which can perform MS/MS, to produce characteristic fragments of isobaric species.