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2.2.7 Analytical problems and method development 
The aim of the project was to develop methods for the determination of these target 
compounds at ultra-trace levels in marine water, sediments, and biota. Very sensitive 
methods were developed for chlorpyrifos, endosulfan and trifluralin with detection 
limits of <10 pg/L for water, <10 ng/kg for sediment, and <0.5 pg/kg for biota. Sea 
water extraction was performed by solid phase extraction. Sediments and biota were 
extracted by microwave assisted hot solvent extraction with a mixture of 
hexane/acetone. GC-MS in the negative ion chemical ionisation mode was used for the 
determination. 
The limits of detection (LODs) for PCP and dicofol were not quite as low but 
appropriate for this study and comparable with LODs reported for terrestrial surveys. A 
fast HPLC-MS method with detection limits of 0.2 and 0.4 ng/L was developed for PCP 
and the chlorpyrifos degradation product trichloropyridinol (TCPy) in sea water. This 
method was sufficient for screening purposes in river estuaries and at coastal stations, 
but not selective enough for sediment and biota samples. Therefore, additionally a GC- 
NCI-MS method was developed for these matrices, which, however, required a 
derivation of the phenol group. 
Dicofol degraded thermally very quickly during GC-MS analysis. Therefore, a limit of 
quantification (LOQ) of only 1 ng/L could be achieved, which is only sufficient for a 
screening of local hot spots. Since dicofol was found to be unstable in sea water and due 
to time constraints, no method was developed for sediment or biota. 
2.2.8 Chlorpyrifos in the marine environment of the North and Baltic 
Seas 
This is the first time that chlorpyrifos has been detected in quantifiable amounts in the 
marine environment. Chlorpyrifos-methyl was not detectable in the North Sea and 
Baltic Sea. However, the homologue ester chlorpyrifos-ethyl was found in most water 
and biota samples. It was less frequently detected in sediment samples. Observed 
concentrations were very low with a median of 26 pg/L in water samples and 9 ng/kg