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

[摘要] During the MINOS campaign in August 2001 comprehensivetwo-dimensional gas chromatography (GC x GC) was applied to the in situ measurements of atmospheric volatile organic compounds(VOCs) at the Finokalia ground station, Crete. The measurement system employs a thermal desorption unit for on-line sampling andinjection, and a GC x GC separation system equipped with a flame ionization detector (FID) for detection. The system wasoptimized to resolve C₇-C₁₄ organic components. Two-dimensional chromatograms from measurements of Finokalia airsamples show several hundred well-separated peaks. To facilitate peak identification, cartridge samples collected at Finokalia wereanalyzed using the same GC x GC system coupled with a time-of-flight mass spectrometer(TOF-MS). The resulting mass spectra were deconvoluted and compared to spectra from a databasefor tentative peak identification. About 650 peaks have been identified in the two-dimensional plane, with significantsignal/noise ratios (>100) and high spectra similarities (>800). By comparing observed retention indices with those foundin the literature, 235 of the identifications have been confirmed. 150 of the confirmed compounds show up in theC₇-C₁₄ range of the chromatogram from the in situ measurement. However,at least as many peaks remain unidentified. For quantification of the GC xGC measurements, peak volumes of measured compounds have been integrated and externally calibrated using a standardgas mixture.

[学科分类] 大气科学