GASOLINE LEAKAGE FORENSICS USING COMPOUND-SPECIFIC HYDROGEN ISOTOPE ANALYSIS - A CASE STUDY

摘要

Present day industrial activities introduce significant amounts of petroleum-based products into the natural environment from events such as leaking storage tanks and pipelines and oil spills associated with routine shipping operations.1 Consequently petroleum hydrocarbons are the most commonly detected organic contaminants in groundwater.2 Molecular fingerprinting using gas chromatography - mass spectrometry (GC/MS) is a conventional approach to identify the source of a particular contaminant plume or event. However, during migration the molecular profiles of contaminant plumes often change due to mixing with other sources and physical/biological weathering, making a conclusive match between the source and the pollutant difficult. Although triterpanes and steranes are commonly used as biomarkers for source correlation because of their resistance to microbial degradation,3 these biomarker compounds are generally absent from the lighter refined petroleum products, such as gasoline. Compound-specific isotope analysis (CSIA) has become a powerful tool for studying the sources and environmental fate of organic contaminants. The ability to measure the isotopic composition of the organic contaminant itself has been facilitated by gas chromatography-isotope ratio mass spectrometry (GC-IRMS), which allows for the measurement of the isotopic composition of individual compounds within a complex mixture.4"6 GC-IRMS provides rapid, cost-effective analysis with four to five orders of magnitude more sensitivity than conventional labor-intensive "offline preparation and dual-inlet measurement" techniques.