22 
Fig. 15: GCs of HFO samples containing different amounts of aromatics from cracking 
processes (aromatics are hardly discernible in the upper right sample - and not 
discernible in the lower right sample). 
Since FIFOs contain different amounts of high-boiling compounds, which cannot pass the GC 
(see 2.3.1 Analysis), proper categorization of higher HFO grades by means of GC techniques 
is hardly possible. The IFO380 in Figure 16 (upper left chromatogram), can hardly be 
differentiated from the IFO180 (upper right sample). As a very vague rule, it can be stated 
that higher-boiling grades are often recognized by a higher and broader UCM in the high- 
boiling region. The two IFO30 (lower samples) can be easily distinguished from such oils 
because of their limited boiling range. 
Fig. 16: Gas-chromatograms of IFO380 (upper left), IFO180 (upper right) and two IFO30 
bunker oils (below).