Quantification of biogenic volatile organic compounds with a flame ionization detector using the effective carbon number concept

[摘要] Biogenic volatile organic compounds (BVOCs) are emitted into the atmosphereby plants and include isoprene, monoterpenes, sesquiterpenes, and theiroxygenated derivatives. These BVOCs are among the principal factorsinfluencing the oxidative capacity of the atmosphere in forested regions.BVOC emission rates are often measured by collecting samples onto adsorptivecartridges in the field and then transporting these samples to thelaboratory for chromatographic analysis. One of the most commonly useddetectors in chromatographic analysis is the flame ionization detector(FID). For quantitative analysis with an FID, relative response factors maybe estimated using the effective carbon number (ECN) concept. The purpose ofthis study was to determine the ECN for a variety of terpenoid compounds toenable improved quantification of BVOC measurements. A dynamic dilutionsystem was developed to make quantitative gas standards of VOCs with mixingratios from 20–55 ppb. For each experiment using this system, one terpenestandard was co-injected with an internal reference, n-octane, and analyzedvia an automated cryofocusing system interfaced to a gas chromatograph flameionization detector and mass spectrometer (GC/MS/FID). The ECNs of 16compounds (14 BVOCs) were evaluated with this approach, with each testcompound analyzed at least three times. The difference between the actualcarbon number and measured ECN ranged from −24% to −2%. The differencebetween theoretical ECN and measured ECN ranged from −22% to 9%.Measured ECN values were within 10% of theoretical ECN values for mostterpenoid compounds.

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