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2.1.1 Analysis 
2.1.1.1 GC screening 
Light fuel oil is easily detected in GC screening because of its limited boiling range: 
compounds end at about n-C25. This n-alkane has a boiling point of about 400 °C (Fig. 2). 
Accordingly, the possibilities of comparing two light fuel oil samples are rather limited. 
Weathering effects, which are quite common (see above), are even more severe in this case 
because they lead to further limitations in sample comparison. 
Light fuel oil samples can be differentiated by the shapes of the envelopes of the n-alkanes, 
the shapes of the envelopes of the “unresolved complex mixture” (UCM), which mainly 
consists of naphthenes (cyclo-alkanes), and their Cn/pristane, Cis/phytane, and 
pristane/phytane ratios (Fig. 2 and Fig. 3). 
Fig. 2: Gas-chromatogram of a typical light fuel oil. The envelopes of the n-alkanes 
and the UCM, Cn, pristane, Cis, phytane and C25 (computer calculations) 
are shown. 
A Given here is the general evaluation of the GC screening results of oil samples 
(“first look”). Further peaks appearing in between the homologues series of the n- 
alkanes, such as nor-pristane, further isoprenoids and pronounced naphthenes, 
might provide further information if present.