Hydrocarbons progressive identification

Fig. 5.1 Progressive identification of hydrocarbons in roasted coffee volatiles...

Due to the fact that JP-8 contains hundreds of aliphatic and aromatic hydrocarbons, in addition to various performance additives, this complex mixture poses a serious challenge for risk assessment. Exposure assessment is complicated by the fact that JP-8 may be encountered as a vapor, aerosol, or liquid, and possibly as combustible products, and each physical state may contain different chemical entities. However, progress has been made in the identification of JP-8 components that may serve as reliable and predictable biomarkers of exposure, particularly for dermal exposures [12,35,81,82,83,84],... 

This work has demonstrated that organically bound sulfur forms can be distinguished and in some manner quantified directly in model compound mixtures, and in petroleum and coal. The use of third derivatives of the XANES spectra was the critical factor in allowing this analysis. The tentative quantitative identifications of sulfur forms appear to be consistent with the chemical behavior of the petroleum and coal samples. XANES and XPS analyses of the same samples show the same trends in relative levels of sulfide and thiophenic forms, but with significant numerical differences. This reflects the fact that use of both XPS and XANES methods for quantitative determinations of sulfur forms are in an early development stage. Work is currently in progress to resolve issues of thickness effects for XANES spectra and to define the possible interferences from pyritic sulfur in both approaches. In addition these techniques are being extended to other nonvolatile and solid hydrocarbon materials. 

---