揮発性有機化合物の直接その場分析に向けたプロトン移動反応イオン化-マルチターン飛行時間型質量分析装置の開発

抄録

Volatile organic compounds (VOCs) are ubiquitous gas species produced by various natural and anthropogenic processes, including burning fossil fuels, biomass burning, and biological activities. They are byproducts of numerous biological processes and an important causative agent of air pollution, such as photochemical oxidants and atmospheric particle matter (e.g., PM_2.5).VOCs are diverse and highly chemically reactive; therefore, on-site real-time monitoring of the wide variety of VOCs, including unidentified ones and short-lived intermediates, is quite essential. We developed a prototype version of a portable, high-resolution, high-precision mass spectrometer for the VOCs’ real-time and on-site measurement by coupling a multi-turn time-of-flight mass spectrometer (MULTUM) and a simple proton transfer reaction (PTR) ion source. Performance evaluation confirmed that the mass resolving power was currently more than 7,000, although a temporal ion optics configuration limited it. Using a linear ion trap for ion accumulation significantly improved the signal-to-noise ratio of the mass spectrum. Linear response for two orders of concentrations and the limit of detection around 4 ppbv for one-minute data accumulation was attained for VOCs standard gas samples. Although the prototype has limited instrumental performance, with further fully taking advantage of the MULTUM, the PTR-MULTUM will be a unique addition to PTR mass spectrometry for VOC profiling.