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substances in the field of water policy. Moreover, no risk assessment has been carried 
out in the EU. 
Chlordane is lipophilic and has a high octanol-water partitioning coefficient 
Kow-Chlordane can be dispersed by atmospheric long-range transport. This has led to a 
significant chlordane input into the European Arctic. Since hardly any data are available 
about chlordane levels in Central Europe, this pesticide was included into this 
investigation. 
Oxychlordane and cis-heptachlorepoxide are chlordane metabolites and were never 
produced. Unlike other chlordane degradation products, they are very persistent, 
lipophilic and accumulate even more effectively than their precursors in biota. 
Therefore, they were included into the investigation. 
2.1.3 Analytical problems of PCAs 
Information about environmental levels is still very scarce. The main reason is the 
complex composition of PCAs, which caused tremendous analytical problems. High 
resolution gas chromatography cannot resolve them into single compounds. Moreover, 
mass overlap occurs between PC A compounds of different chain length and degree of 
chlorination as well as other polychlorinated pollutants requiring normally high 
resolution mass spectrometry. Electron capture negative ion (ECNI) chemical ionisation 
mass spectrometry is needed to obtain reasonable low detection limits. However, 
response factors are highly dependent on the degree of chlorination of PCAs present in 
samples and require a careful selection of the quantification standards. Otherwise, 
systematic errors of several hundreds of percents are possible. Moreover, up to thirty (!) 
analyses by mass spectrometry were needed for a complete pattern of one sample 
including all PCA compounds of different chain length and degree of chlorination. 
Finally, so far clean-up techniques were not able to remove other disturbing 
polychlorinated pollutants as PCBs. Therefore, PCA concentrations published so far are 
in many cases indicative and hardly comparable between studies.