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lipid weight, see Table 32; Karlsson, 2000). Therefore, chlordane was included in this
study to extend the existing data about levels in European marine fish and sediments.
This was possible, because a validated analysis method already existed for biota and
therefore only a method adaptation for sediments was necessary.
5.2 Survey about properties of PCAs and chlordane
5.2.1 Polychlorinated n-alkanes (PCAs)
Polychlorinated n-alkanes (PCAs, also called chlorinated paraffins or CPs) are complex
technical mixtures containing thousands of different isomers, congeners, diastereomers
and enantiomers (Muir et al., 2000). They are produced by radical chlorination of n-
alkanes in presence of UV light or heating. The chlorine content of the products varies
between 30 and 70 %. PCAs are divided into short chain PCAs (C10-13, sPCAs),
medium chain PCAs (C14 17, mPCAs) and long chain PCAs (C>n, lPCAs) depending on
the length of the carbon chain. Since their first large scale usage in 1932 as extreme
pressure additives, the purity of PCA products was improved by increasing the purity of
the 77-alkanc feedstocks (Muir et al., 2000). Modem commercial products contain
additives to inhibit decomposition of PCAs by loss of HC1 at elevated temperatures and
to increase thermal stability when used as flame retardants (e.g. antimony oxide). Other
common stabilizers include epoxides and organotin compounds (GDCh, 1996).
Depending on chain length and chlorine content, PCAs are colourless or yellowish, low
to highly viscous liquids or glassy to waxy solids. PCAs are thermally stable up to 200-
300 °C. Environmentally important physical-chemical properties of PCAs such as
vapour pressure, water solubility and water-octanol distribution are summarised in
Table Table 8.
As consequence of the different physical and chemical properties, miscellaneous PCA
formulations are used for a wide range of applications. Some examples are: Additives in
metal working fluids (short, medium, and long chain PCAs, 50-60 % Cl content),
secondary plasticizers in polyvinyl chloride and in other plastics (usually mPCAs, 40-
