9 
ships, and it is often difficult or even impossible to take samples from all potential sources. In 
such cases, the “identity” between a spill sample and a sample from a possible source may be 
virtually meaningless, the only certainty being that the comparison sample has actually been 
taken from one of the many potential sources. 
Because of these limitations, close cooperation with the prosecuting authorities is advisable. 
After the main characteristics of the light fuel oil have been determined by GC screening (see 
below) in-depth analyses should only be performed if they are justified by the particular 
circumstances of the case, in order to save costs and laboratory resources. 
Once released onto the water surface, light fuel oils spread very rapidly. In open waters, very 
large and thin films will form. The large film surface may lead to rapid, severe weathering of 
the oil. 
Because of the thin oil film, only small sample volumes can be obtained from such spills, and 
there is a high risk of sample contamination by organic pollutants or natural, biogenic 
compounds from the surrounding water. 
Fig. 1: Gas chromatograms of a heavily weathered light fuel oil (spill sample, above) and the 
original product (below). Besides strong evaporation which took place in the spill, all 
of the n-alkanes have been removed by bacterial degradation. Compounds originating 
from the surrounding water are also present in the spill sample.