On the development of a new prototype PTR-ToF-MS instrument and its application to the detection of atmospheric amines

Abstract

We herein report on the development of a new prototype PTR-ToF-MS (proton-transfer-reaction time-of-flight mass spectrometry) instrument that combines a hollow cathode glow discharge (HCGD) ion source with a focusing ion-molecule reactor (FIMR), which consists of a resistive glass drift tube surrounded by quadrupole rods. The new instrument configuration hybridizes the two main current commercial PTR-ToF-MS instrument designs. We provide a detailed technical description of the new analyzer and its optimized operational settings for detecting volatile amines via proton transfer reactions from hydronium (H3O+) or ammonium (NH4+) ions. We show that the new prototype PTR-ToF-MS instrument is capable of monitoring rapid changes of sticky amines on the timescale of a few seconds and detects atmospheric variations of amines down to single-digit parts per trillion by volume (pptv) levels. Application examples given include the real-time monitoring of (i) methylamine emitted from a Chenopodium vulvaria L. plant, (ii) small alkylamines in ambient air on site of an agricultural research center (Senter for husdyrforsøk, Ås, Norway), and (iii) an industrial amine (2-amino-2-methylpropan-1-ol, AMP) on site and downwind of a carbon dioxide (CO2) capture test center (Technology Centre Mongstad - TCM, Mongstad, Norway).