Field evaluation of a novel charge transfer ionization TOF MS for ambient VOC measurements

Abstract. A newly developed charge transfer orthogonal Time-of-Flight Mass Spectrometer (oToF-MS), was deployed for the first time in the field in order to evaluate its ability to perform online real-time measurements of volatile organic compounds (VOCs) for a prolonged time period. The study focused on urban air sampling and targeted a specific range of VOCs, namely: acetone, isoprene, benzene, toluene, and xylene. The measurement campaign took place from May to August 2023 at the suburban area in Athens Greece. The measured VOC level were consistent with those reported in previous summer campaigns suggesting that the instrument did not face any unexpected problems moving from the laboratory to the field. The variability of the measurements of the various VOCs was used to gain insights about their sources. Transportation emissions were a dominant source of the BTX compounds (benzene, toluene and xylene). Acetone and isoprene were emitted by both anthropogenic and biogenic sources. During the summer biogenic sources were responsible for most of the isoprene in the site.