19 
Oil Spill identification - Round Robin 20045 
Cedre remarks that the biomarkers have a low abundance and a high 
variance. This is shown on page 12 of their report between Source I 
and Extract I for e.g. %32abS and %30g. 
Several other participants use the same instrument (see 6.2) and were 
able to analyze the biomarkers with a good sensitivity and a low 
variance. In the report of Cedre no information about the injection 
concentration could be found. 
The method applied is quite normal although the injection temperature 
is lower than most participants use. 
RIZA has tested the injection temperature for the GC-FID analysis with 
a split/splitless injector at 300°C, 325°C and 350°C and found a better 
performance and a lower variance of the alkanes in the range of C30- 
C44. Using the split/splitless injector in a series at a temperature of 
350°C however resulted in a fast decrease of the performance of the 
rubber sealing around the liner, although a high temperature ring was 
used. 
Based on that a temperature of 325°C is used for the split/splitless 
injector (GC-FID) and 350°C for the PTV injector (GC-MS). 
2.3 LASEM 
Contact: Pauline Pierre 
LASEM is a laboratory of the ministry of Defense and is located in Brest. 
The samples have been analyzed with GC-MS in the full scan mode 
(m/z 50 - 300) with an ion trap as detector. 
=> In first approximation, the chromatogram of the four samples have the 
same shape: mixture of light and heavier oils. 
The comparison between the n-alkanes repartition of the four samples shows 
differences in low boiling rang, but it could come from volatility of these 
compounds: it does not allow to differentiate them. 
The usually used biomarkers do not permit to conclude, because of their too 
low abundance. Diagnostic ratios coming from the PAH’s, present more or 
less significant differences, depending on the considered ratio. 
As a conclusion, 
Oil spills at day 1 seem to be different from source I and II, 
Oil spills at day 2 seem to be different from source I and II, 
Source I and source II are different, 
Oil spill at day 1 seems to have the same source as the day 2’s. 
Notes/remarks: 
LASEM reports: 
The usually used biomarkers do not permit to conclude, because of their too 
low abundance. 
RIZA has diluted the extract 8 times and diluted 3 ul of the source 
samples in 1 ml DCM. Injections of 1 ul resulted in a good sensitivity 
with about the same peak height for all samples (see fig 11 of the RIZA 
report)