Fingerprinting Analysis and Source Differentiation of Petroleum-Contaminated Environmental Samples

This chapter presents specific cases to describe how to apply forensic chemical fingerprinting to characterize and differentiate biogenic and pyrogenic hydrocarbons from petrogenic hydrocarbons in various petroleum-contaminated environmental samples. The most important criteria from quantitative chromatographic analyses are concentrations, distribution profiles and diagnostic ratios of source-specific petroleum compounds such as normal alkanes and isoprenoids, unsubstituted PAHs (polycyclic aromatic hydrocarbons) and their alkylated series, biomarker terpanes and steranes, bicyclic sesquiterpanes and diamondoids. Chromatographic profiles of gas chromatography–flame ionization detection detectable component and distribution of normal alkanes provide primary diagnostic information for the identification and differentiation of petrogenic and biogenic sources. PAH distributions and associated diagnostic ratios, such as pyrogenic index and perylene index, are very useful tools in distinguishing petrogenic hydrocarbons from both pyrogenic and biogenic hydrocarbons. As petroleum-characteristic alkylated PAH homologues and biomarkers are rarely recognized in biogenic and pyrogenic sources, their co-occurrence can be used as an unambiguous indicator of petrogenic contamination, whereas the absence of petroleum-characteristic component and presence of abundant biogenic compounds such as dominant odd-numbered n-alkanes, sterols, fatty acids and alcohols could serve as strong evidences of a predominance of natural organic compounds in samples.