5
Summary
Similarities or dissimilarities in gas chromatograms and mass chromatograms of oils are not
easily discernible by non-experts in the field of oil identification. Compound ratios, i.e. relative
concentrations of compounds, represent more measurable, objective and defensible means
for the verification of results in Oil Spill Identification. A European Standard for Oil Spill
Identification is being prepared by CEN Technical Board's Task Force 120 in order to
improve existing methods (Nordtest ChemOOl, ASTM D 3415 ) especially in this regard.
Based on the revision of the Nordtest-procedure (L.-G. Faksness et. al, SINTEF-Report
STF66 A02028, May 2002, http://www.nordtest.org/register/techn/tlibrary/tec498.pdf), a set
of 23 parameters (“useful minimum set”) for comparing two oil samples is proposed.
However, this set of parameters has been derived from crude oil research and is based on
geochemical findings. In the case of oil products involved in an oil spill, certain parameters
simply are not present in the sample, or their meaning, and thus their value for oil
identification, has been changed by the production process. But oil products, mainly in form
of waste oil, are the major source of oil pollution in all areas of higher shipping traffic.
Therefore, guidance is given on how to handle the proposed parameters with respect to the
different characteristics of oil types. The identification of the type of oil involved in an oil spill
thus is essential, and a step-by-step procedure is provided for identifying the oil type, even in
(highly) weathered samples.
But even in a comparison of two crude oil samples, some of the parameters may be much
more important than others. Their value is highly dependent on the circumstances of each
particular case. Some examples are shown.
