Novel characterization of the aerosol and gas-phase composition of aerosolized jet fuel

Abstract

Few robust methods are available to characterize the composition of aerosolized complex hydrocarbon mixtures. The difficulty in separating the droplets from their surrounding vapors and preserving their content is challenging, more so with fuels, which contain hydrocarbons ranging from very low to very high volatility. Presented here is a novel method that uses commercially available absorbent tubes to measure a series of hydrocarbons in the vapor and droplets from aerosolized jet fuels. Aerosol composition and concentrations were calculated from the differential between measured total (aerosol and gas-phase) and measured gas-phase concentrations. Total samples were collected directly, whereas gas-phase only samples were collected behind a glass fiber filter to remove droplets. All samples were collected for 1 min at 400 ml min(-1) and quantified using thermal desorption-gas chromatography-mass spectrometry. This method was validated for the quantification of the vapor and droplet content from 4-h aerosolized jet fuel exposure to JP-8 and S-8 at total concentrations ranging from 200 to 1000 mg/m(3). Paired samples (gas-phase only and total) were collected every approximately 40 min. Calibrations were performed with neat fuel to calculate total concentration and also with a series of authentic standards to calculate specific compound concentrations. Accuracy was good when compared to an online GC-FID (gas chromatography-flame ionization detection) technique. Variability was 15% or less for total concentrations, the sum of all gas-phase compounds, and for most specific compound concentrations in both phases. Although validated for jet fuels, this method can be adapted to other hydrocarbon-based mixtures.

Development of a physiologically based pharmacokinetic model for inhalation of jet fuels in the rat

“…With advances in analytical methodology and the recent interest in synthetic fuels and bio-fuels, there is an important need to better characterize the exposure and dosimetry of complex hydrocarbon mixtures, such as fuels. The hydrocarbon composition of non-fossil fuels is different from fossil fuels (Tremblay et al, 2010b). Limited toxicity studies exist for the new alternative fuels (Wong et al, 2009;Wong et al, 2008).…”

“…Martin et al (2010) described in detail the inhalation exposure system and the techniques for generating atmospheric levels of hydrocarbons. Tremblay et al (2010b) and Martin et al (2010) described the analytical methods used to characterize the chamber atmosphere for aerosolized fuel exposures. In brief, individual hydrocarbon concentrations, lumped hydrocarbon concentrations (described later), and the total hydrocarbon concentration (THC) within the exposure chamber were quantified using a combination of thermal desorption tubes and gas chromatography (GC), with mass spectrometry (MS) used for individual and lump fractions, and flame ionization detector (FID) for the THC Tremblay et al, 2010b).…”

“…The hydrocarbon fractions or individual hydrocarbons responsible for the reported toxicity of inhaled fuel remain unknown. Our multi-hydrocarbon fuel PBPK model was developed primarily based on prominence of individual hydrocarbons in the inhalation atmosphere (Tremblay et al, 2010b) and their presence in blood of exposed rats.…”

“…Xylenes (m, p and o) were all 99+% pure (Sigma-Aldrich, St. Louis, MO). A purchased standard (Tremblay et al, 2010b) was used for all other branched aliphatic chemicals (PIONA-Mixture 2, S-4136, Chiron AS, Trondheim, Norway). Specifically, PIONA-Mixture 2 contained 37 isoparaffins of varying Wt%, (listed as name and Wt.%): Isopentane (2.6), 2,3-Dimethylbutane (1.4), 2-Methylpentane (4.4), 3-Methylpentane (3.2), 2,2-Dimethylpentane (4.2), 2,4-Dimethylpentane (3.1), 2,2,3-Trimethylbutane (3.1), 3,3-Dimethylpentane (1.3), 2-Methylhexane (3.6), 2,3-Dimethylpentane (1.6), 3-Methylhexane (4.5), 3-Ethylpentane (1.6), 2,2-Dimethylhexane (1.4), 2,5-Dimethylhexane (3.2), 2,2,3-Trimethylpentane (3.2), 2,4-Dimethylhexane (1.6), 2,3-Dimethylhexane (1.4), 2-Methylheptane (4.6), 4-Methylheptane (3.4), 3-Methylheptane (3.8), 3-Ethylheptane (2.9), 2,5-Dimethylheptane (3.1), 3,5-Dimethylheptane (D) (0.4), 3,3-Dimethylheptane (3.3), 3,5-Dimethylheptane (L) (0.4), 2,3-Dimethylheptane (1.5), 3,4-Dimethylheptane (D) (1.7), 3,4-Dimethylheptane (L) (2.0), 2-Methyloctane (5.1), 3-Methyloctane (2.7), 3,3-Diethylpentane (3.3), 2,2-Dimethyloctane (3.1), 3,3-Dimethyloctane (1.7), 2,3-Dimethyloctane (1.6), 2-Methylnonane (3.3), 3-Ethyloctane (3.3), 3-Methylnonane (3.4).…”

“…Pharmacokinetic studies for jet fuel were conducted using a nose-only chamber exposure system for rats Tremblay et al, 2010b). The hydrocarbon composition of inhaled aerosolized fuel was characterized for the vapor and aerosol droplet phases and blood and tissue time-course hydrocarbon concentration data collected for the development of a jet fuel PBPK model for rats; using petroleum derived jet fuel (JP-8), a synthetic fuel (S-8), synthesized from natural gas by the Fischer-Tropsch process, and a blend of both fuels.…”