20 
Oil Spill identification - Round Robin 20045 
LASEM has diluted the extracts a factor 2 and diluted 100pJ of the 
source samples in 1 ml DCM. The injection volume is 1 pi. As a result 
the source samples should give about a 10 times higher signal than the 
spill samples. In annex IV the areas of m/z 216 are shown. From the 
table the mean and RSD has been calculated: 
extract I 
extract II 
Source I 
Source II 
m/z=216 
mean 
RSD in % 
mean 
RSD in % 
mean 
RSD in % 
mean 
RSD in % 
2M-fluoranthene 
23055 
8.4 
23079 
9.6 
67871 
84.8 
83779 
23.8 
benzo(a)fluore 
ne 
60827 
7.4 
58517 
2.9 
233463 
64.0 
277480 
21.1 
benzo(b)fluoren 
e 
24226 
11.4 
23276 
4.5 
71067 
53.6 
69110 
42.8 
2M-pyrene 
14071 
21.5 
14846 
4.7 
135941 
77.2 
177571 
19.8 
4M-pyrene 
29785 
11.6 
30783 
3.6 
216228 
52.9 
306144 
9.5 
1 M-pyrene 
18138 
8.2 
17829 
1.6 
106854 
49.6 
150598 
8.4 
Table 1. The source results show much higher RSD's than the extract results. 
Mean and RDS calculated from annex 
IV of the LASEM report 
From the table with the analytical methods (see 7.2 of this report) it 
can be seen that LASEM uses the lowest injection temperature of all 
participants. This subject is discussed in 2.3 Cedre. 
It can also be see that only LASEM uses an ion trap for the biomarker 
analysis. Petrobas uses the same instrument for the PAH analysis, but 
uses a quadrupole instrument for the biomarkers. 
An ion trap has to reduce the total number of ions in the source to 
prevent chemical ionization reactions and to be able to filter the ions 
properly. Therefore the number of ions is measured before each scan 
and only a limited number is entering the source. It is therefore possible 
that for the samples of RR2005 the number of biomarker ions 
compared to the total number of ions is so small that it is difficult to 
analyze them correctly with an ion trap. 
Note: An email to Petrobas with a request for the reason why the ion 
trap is not used for biomarkers has not been answered before finishing 
the report. 
Advise: 
Optimize the injection concentration for bilge samples by 
means of a calibration line 
Validate the instrument by means of 7 to 8 injections and 
calculate the relative st dev of (some of the) the ratios. They 
should not be much higher that 5%. 
Analyze the same samples on a GC-MS with a quadrupole 
detector when possible and compare the results. 
2.4 LVA 
Contact: Rita Skolmeistere