Petroleum hydrocarbon screening using SPME analysis of the Water Associated Fraction

The ability to differentiate petroleum oils based on the relative proportions of soluble components from the original hydrocarbon mixtures has been studied. The results reported are for the analysis of these dissolved hydrocarbons dispersed in aqueous solution. The extraction from the aqueous phase was conducted using direct immersion of a polydimethylsiloxane Solid Phase Micro Extraction (SPME) stationary phase into water containing the dissolved hydrocarbons. Relatively small volumes of water (25 ml) could be sampled in this way whereas solvent extraction was found to be unsuccessful. The 21 oils from various sources worldwide were analysed in this study, and it has been found that similar to the chromatograms of the “as received” oils, the Water Associated Fraction (WAF) could be used to distinguish these oils.
Temporal changes to the WAF were also examined, in particular the influence of evaporation during initial periods of WAF formation.