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

Abstract

Abstract. Biogenic volatile organic compounds (BVOCs) are emitted into the atmosphere by plants and include isoprene, monoterpenes, sesquiterpenes, and their oxygenated derivatives. These BVOCs are among the principal factors influencing the oxidative capacity of the atmosphere in forested regions. BVOC emission rates are often measured by collecting samples onto adsorptive cartridges in the field and then transporting these samples to the laboratory for chromatographic analysis. One of the most commonly used detectors in chromatographic analysis is the flame ionization detector (FID). For quantitative analysis with an FID, relative response factors may be estimated using the effective carbon number (ECN) concept. The purpose of this study was to determine the ECN for a variety of terpenoid compounds to enable improved quantification of BVOC measurements. A dynamic dilution system was developed to make quantitative gas standards of VOCs with mixing ratios from 20-55 ppb. For each experiment using this system, one terpene standard was co-injected with an internal reference, noctane, and analyzed via an automated cryofocusing system interfaced to a gas chromatograph flame ionization detector and mass spectrometer (GC/MS/FID). The ECNs of 16 compounds (14 BVOCs) were evaluated with this approach, with each test compound analyzed at least three times. The difference between the actual carbon number and measured ECN ranged from −24 % to −2 %. The difference between theoretical ECN and measured ECN ranged from −22 % to 9 %. Measured ECN values were within 10 % of theoretical ECN values for most terpenoid compounds.

A novel fast gas chromatography method for higher time resolution measurements of speciated monoterpenes in air

“…The response factors for the individual monoterpenes were comparable (all within ∼ 15 % of the α-pinene response), with the exception of myrcene, which produced an FID response ∼ 25 % lower than that of α-pinene. It is notable that a similar myrcene/α-pinene relative FID response ratio was observed by Faiola et al (2012). It should also be noted that since the monoterpene camphene is solid at room temperature, in this case the FID response was assumed to be equivalent to that of β-pinene.…”

Impacts of simulated herbivory on volatile organic compound emission profiles from coniferous plants

“…This instrument was equipped with a custom-built pre-concentration system described previously by Faiola et al (2012Faiola et al ( , 2014a. The pre-concentration unit traps analytes on the Tenax © GR adsorbent and uses thermodesorption to inject compounds into the GC system.…”

“…The FID is essentially a "carbon counter", meaning that the current produced from the detector is a function of the number of carbons in the molecule. Consequently, if the structure of the molecule is known, the concentration may be quantified using the effective carbon number concept with an upper-limit instrumental error of ±10 % (Faiola et al, 2012). Identifications of the following compounds could be made based on retention times determined using commercial standards: 3-carene, terpinolene, limonene, alphapinene, beta-pinene, alpha-terpinene, beta-myrcene, and ocymene.…”

“…Effective carbon numbers were estimated using the effective carbon number concept (Faiola et al, 2012;Sternberg et al, 1962). Biomass was estimated by collecting and weighing a subset of needles from each tree after they were removed from the plant chamber.…”

Quantitative Approaches for the Determination of Volatile Organic Compounds (VOC) and Its Performance Assessment in Terms of Solvent Types and the Related Matrix Effects

“…Realistically, because of the presence of complex mixtures of organic compounds in environmental samples, it is nearly impossible or impractical to prepare and spike all authentic analytical standards into the matrix (either gas or liquid) of a sample. Many researchers have been trying to resolve this issue through the generation of predictive equations to compensate the unavailability of authentic standards such as the use of effective carbon number (ECN) concept (Faiola et al, 2012;Kállai et al, 2001;Jones, 1998). According to Morris and Chapman (1961), the basic concept of ECN was described and stated as, "The molar response of a compound in the hydrogen flame detector can be estimated by summing the atomic contributions and multiplying by a proportionality constant characteristic of burner configuration and operating conditions employed."…”