Use of Rapid Reduced Electric Field Switching to Enhance Compound Specificity for Proton Transfer Reaction-Mass Spectrometry

The high sensitivity of proton transfer reaction-mass spectrometry (PTR-MS) makes it a suitable analytical tool for detecting trace compounds. Its specificity is primarily determined by the accuracy of identifying the m/z of the product ions specific to a particular compound. However, specificity can be enhanced by changing the product ions (concentrations and types) through modifying the reduced electric field. For current PTR-MS systems, this is not possible for trace compounds that would only be present in the reaction chamber of a PTR-MS for a short time (seconds). For such circumstances, it is necessary to change the reduce electric field swiftly if specificity enhancements are to be achieved. In this paper we demonstrate such a novel approach, which permits any compound that may only be present in the drift tube for seconds to be thoroughly investigated. Specifically, we have developed hardware and software which permits the reaction region’s voltages to be rapidly switched at a frequency of 0.1–5 H...