Gas chromatography mass spectrometry analysis of volatile organic trace gases at Mauna Loa Observatory, Hawaii

Volatile organic trace gases in the remote troposphere at the Mauna Loa Observatory were identified in July and August 1992 during the Mauna Loa Observatory Photochemical Experiment (MLOPEX 2) using an in situ fully automated gas chromatography mass spectrometry (GCMS) instrument. Identification was obtained for 65 organic compounds, 7 additional compounds were identified tentatively. Four target parts per trillion (ppt)‐level species were detected in the selected ion monitoring mode (SIM). The experimental data show typical background air characteristics; for example, abundance of long‐lived compounds such as halogenated hydrocarbons during all measurement periods. Volatile organic compounds (VOCs) from local sources from the island were also seen during daytime upslope flow conditions. These included short‐lived biogenic hydrocarbons such as isoprene and monoterpenes and typical emissions from combustion processes such as alkylated aromatics.