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

Abstract

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.During the fourth field campaign of MLOPEX 2 in July and August 1992, gas chromatography mass spectrometry (GCMS) measurements of volatile organic trace gases were made at the site. The purpose of the GCMS experiment was to (1) support the GCFID measurements and confirm peak assignments of quantified species, (2)identify possible interferences from coeluting compounds in the GCFID measurements, (3) identify unknown compounds observed in the FID chromatograms, (4) provide reliable identification of a series of compounds tentatively identified as n-aldehydes and observed in the GCFID chromatograms in the previous field measurements (both in MLOPEX 1 and in the first three campaigns of MLOPEX 2), and (5) to allow detection of additional organic compounds that were undetected on the GCFID system. The measurements were also meant to contribute to the identification of long-lived organic trace gases at MLO and to provide additional information on the distribution of volatile organic trace gases among different chemical compound classes. ExperimentalThe GCMS experiment solely allowed qualitative measurements for compound identification, because with the changing sensitivity of the MS among different compounds, quantitative measurements would require calibration standards for each individual compound in the concentration range of the samples. The GCMS analytical system employed. has been described in detail recently [Hehnig and Greenberg, 1994] and only a brief summary of the basic principles will be given here. The inlet port was located on top of a measurement tower at about 9 m above ground. In order to accomplish compound identification on the mass spectrometer in the full scan mode, substantially larger sample volumes than the 2 1 14,697

Comprehensive two-dimensional gas chromatography (GC × GC) measurements of volatile organic compounds in the atmosphere

“…In fact, most of the compounds have already been detected in previous observations at urban and remote sites mainly using GC-MS (e.g. Ciccioli et al, 1992Ciccioli et al, , 1993Helmig et al, 1996). Due to direct emissions of organic species from anthropogenic and biogenic sources and photochemical production of secondary organic species, the lower atmosphere always contains a large number of VOCs, even in Antarctic (Ciccioli et al, 1996).…”

“…2a), but there are some differences between both chromatograms. On the TIC chromatogram there seems to (2001); (2) Hayes and Pitzer (1985); (3) prediction using the method of Zenkevich (1998); (4) HaagenSmit Laboratory (1997); (5) Laub and Purmell (1988); (6) Lubeck and Sutton (1984); (7) Helmig et al (1996); (8) Bermejo et al (1987); (9) Andrade et al (2000); (10) (2000); (15) Madruga and Mottram (1998); (16) Weber (1986) be a band 0.4 s above the lowermost band (i.e. the alkane band).…”

“…Helmig et al, 1996;Rappenglück et al, 1998;Wedel et al, 1998). However, conventional GC often fails to separate components in complex samples to a satisfactory degree, being limited by the separation power of a single column.…”

Isoprene and monoterpene fluxes from Central Amazonian rainforest inferred from tower-based and airborne measurements, and implications on the atmospheric chemistry and the local carbon budget

“…The downside of using nonanal is that there are potential interactions (production or deposition) with atmospheric particulate matter (Matsunaga et al, 2003;Bowman et al, 2003;Moise and Rudich, 2002) whose impact on vertical profiles of nonanal can not yet be assessed. Also, there might be potential artefacts during the sampling and analytical procedure (Helmig et al, 1996).…”

GC×GC measurements of C<sub>7</sub>-C<sub>11</sub> aromatic and n-alkane hydrocarbons on Crete, in air from Eastern Europe during the MINOS campaign

“…A common method for simultaneous measurements of many VOCs is to use capillary gas chromatography (GC), in combination with a flame ionization detector (FID) or a mass spectrometer (MS) (e.g. Helmig et al, 1996;Rappenglück et al, 1998;Wedel et al, 1998). However, conventional GC, being limited by the separation power of single column, often fails to separate components in complex samples to a satisfactory degree.…”