Principle of the Measurement
The NOAA GC-MS, also referred to as ACCBAR (Advanced Cryo-mechanical Chromatograph for Biospheric-Atmospheric Research), is a custom-built, two-channel gas chromatograph coupled to a quadrupole mass spectrometer detector (Agilent 5975C). The instrument is capable of collecting in-situ samples for immediate analysis or for automated analysis of the integrated whole air samplers (iWAS). Additionally, the GC front end can be coupled to the NOAA PTR-ToF-MS for identification of isobaric species and mass fragments. The GC-MS utilizes a series of traps to reduce carbon dioxide, ozone, and water prior to preconcentrating volatile organic compounds (VOCs) at liquid nitrogen temperatures via a Stirling Cooler (CryoTel GT by Sunpower Inc.).
C2-C11 hydrocarbons, C1-C8 oxygenated volatile organic compounds, C1-C7 volatiles nitrogen (e.g., nitriles and alkyl nitrates), and other sulfur and halogenated volatiles
Time Response / Detection Limit
Collects a 4-minute sample to preconcentrate VOCs prior to analysis. Total duty cycle is 20 minutes per sample. Detection limits are compound dependent but generally range in the 1-10 parts-per-trillion (ppt).
Custom built instrument utilizing commercial components
Lerner, B.M., J.B. Gilman, K.C. Aikin, E.L. Atlas, P.D. Goldan, M. Graus, R. Hendershot, G.A. Isaacman-VanWertz, A. Koss, W.C. Kuster, R.A. Lueb, R.J. McLaughlin, J. Peischl, D. Sueper, T.B. Ryerson, T.W. Tokarek, C. Warneke, B. Yuan, and J.A. de Gouw, An improved, automated whole-air sampler and gas chromatography mass spectrometry analysis system for volatile organic compounds in the atmosphere, Atmospheric Measurement Techniques, doi:10.5194/amt-10-291-2017, 2017.
Koss, A.R., K. Sekimoto, J.B. Gilman, V. Selimovic, M.M. Coggon, K.J. Zarzana, B. Yuan, B.M. Lerner, S.S. Brown, J.-L. Jimenez, J. Krechmer, J.M. Roberts, C. Warneke, R.J. Yokelson, and J. de Gouw, Non-methane organic gas emissions from biomass burning: identification, quantification, and emission factors from PTR-ToF during the FIREX 2016 laboratory experiment, Atmospheric Chemistry and Physics, doi:10.5194/acp-18-3299-2018, 2018.