7 - Emerging CEN methodology for oil spill identification

Abstract

The objective of the emerging European Committee for Standardization (CEN) methodology is to provide a forensic tool for the identification of waterborne oil by comparing samples from spills with those of suspected sources. The two working groups under the CEN task force BT/TF 120 have produced two draft guidelines that describe the new methodology: part 1—sampling and part 2—analytical methodology and interpretation of results. Two results that can be achieved in forensic oil spill investigation, “identity” and “nonidentity,” depending on whether spill and candidate source samples are “identical” or “nonidentical.” The emerging CEN methodology for oil spill identification is based on a three-level tiered approach, including gas chromatography–flame ionization detection screening of all involved samples (Level 1), gas chromatography–mass spectrometry fingerprinting of selected spill and candidate source samples (Level 2), and correlation of spill and candidate oil samples based on those diagnostic ratios that can be precisely measured and are resistant to weathering effects (Level 3). By statistical treatment of the ratios and an overall assessment of results from all analytical levels, the oil spill identification using this methodology can be concluded with respect to one of four operational and technically defensible terms: positive match, probable match, inconclusive, or nonmatch.