Pyrolysis-GC/MS analysis of contaminated soils in Alaska

In Alaska, the procedures used to quantify petroleum inorganic soil are complicated by the presence of natural organic matter (NOM). A percentage of what appears to be contamination in some soil samples is actually NOM. The "contamination" derived from NOM (i.e., biogenic interference) cannot be quantified separately from petroleum using currently available analytical methods unless a "background" sample that is known to be uncontaminated can be obtained. Proving that a background sample is truly uncontaminated is often problematic, if not impossible. In the research described here, the concentration of biogenic interference in petroleum contaminated soils was inferred using pyrolysis-gas chromatography/mass spectrometry without a background sample by quantifying the concentration of a suite of compounds called "biogenic indicators." These indicators were selected because they are present in NOM, not present in petroleum, and similar in structure and origin to biogenic interference. This paper discusses the method and its limitations.