Measurement of ammonia, amines and iodine compounds using protonated water cluster chemical ionization mass spectrometry
Creators
- 1. CERN, 1211 Geneva, Switzerland
- 2. Johann Wolfgang von Goethe University Frankfurt Am Main, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt Am Main
- 3. ohann Wolfgang von Goethe University Frankfurt Am Main, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt Am Main
- 4. Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villingen
- 5. Ionicon Analytik GmbH, 6020 Innsbruck, Austria
- 6. GSI Helmholtzzentrum für Schwerionenforschung GmbH,
- 7. TOFWERK AG, 3600 Thun, Switzerland
Description
Abstract. Here we describe the design and performance of a new water cluster chemical ionization–atmospheric pressure interface time-of-flight mass spectrometer (CI-APi- TOF). The instrument selectively measures trace gases with high proton affinity such as ammonia and dimethylamine, which are important for atmospheric new particle formation and growth. Following the instrument description and characterization, we demonstrate successful measurements at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber where very low ammonia background levels of ~ 4 pptv were achieved (at 278K and 80%RH). The limit of detection of the water cluster CI-APi-TOF is estimated to be~ 0:5 pptv for ammonia. Although no direct calibration was performed
for dimethylamine (DMA), we estimate its detection limit is at least 3 times lower. Due to the short ion–molecule reaction time and high reagent ion concentrations, ammonia mixing ratios up to at least 10 ppbv can be measured with the instrument without significant reagent ion depletion. Besides the possibility to measure compounds like ammonia and amines (dimethylamine), we demonstrate that the ionization scheme is also suitable for the measurement of trace gases containing iodine. During CLOUD experiments to investigate the formation of new particles from I2, many different iodine-containing species were identified with the water cluster CI-APi-TOF. The compounds included iodic acid and neutral molecular clusters containing up to four iodine atoms. However, the molecular structures of the iodine-containing clusters are ambiguous due to the presence of an unknown number of water molecules. The quantification of iodic acid (HIO3) mixing ratios is performed from an intercomparison with a nitrate CI-APi TOF. Using this method the detection limit for HIO3 can be estimated as 0.007 pptv. In addition to presenting our measurements obtained at the CLOUD chamber, we discuss the applicability of the water cluster Ci-APi-TOF for atmospheric measurements.
Files
Measurement_of_Ammonia_Amines_and_Iodine_Compounds_Using_Water_Cluster_Chemical_Ionization_Time_Of_Flight_Mass_Spectrometry_Data.zip
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Additional details
Related works
- Is derived from
- 10.5194/amt-13-1-2020 (DOI)