40 
Oil Spill Identification - Round Robin 20045 
illustrated figures 2, 3 and 4 have to be considered with care. However, the 
great variability represented by the error bars did not allow to make 
differences between samples. 
NERI had no problems with the RSD's of the hopanes, while the 
sensitivity at RIZA was good. 
M/z 191 Source i a 
Fig 15 
Hopanes of Source i (riza) Different is the low abundance of the triaromatic steranes (m/z 231) 
By means of GC-screening, it was easy to find out that a mixture of 
light fuel oil and lubricating oil was involved. 
The "true" biomarkers", such as the hopanes and steranes thus 
originated from the lubricating oil. But aromatic steranes are not 
present in this type of oil. Instead unresolved peaks on a hump appear. 
Very probably these are the 4-alpha-M-steranes. 
Fig 16. 
Mass 231 (RIZA)