between the region Baden-Württemberg and Schleswig-Holstein with regard to the
contamination levels of oxychlordane and heptachlor exoepoxide.
In order to gain deeper insight into the enantioselective transformation of
oxychlordane and heptachlor exoepoxide, their enantiomeric ratios (ER) were determined by enantioselective cGC. This was not possible for all samples from BadenWürttemberg (in Table 8.16 indicated with “À”) due to co-eluting matrix peaks,
which could not be sufficiently well separated by the HPLC clean-up. The assignment of the order of elution of enantiomers is based on optical rotation measurements after preparative enantiomeric resolution by packed-column GC (König et al.
1994a, b, c). In all samples, with the exception of heptachlor exoepoxide in sample
no. 1, the (À)-enantiomer was preferentially transformed. The same trend was
observed for the (À)-enantiomer of oxychlordane, where the enantiomeric discrimination appeared to be stronger in the liver samples from Baden-Württemberg than in
the samples from the region Schleswig-Holstein. By the way of contrast, the (À)enantiomer of heptachlor exoepoxide was transformed slightly stronger in the liver
samples from Schleswig-Holstein. As it cannot be expected that different enzymatic
systems are encountered in the roe-deer livers of the two German regions, other
explanations for this regional change have to be checked, for example, different
physical conditions of the animals, which in turn may be influenced by different
diseases or by stress induced by environmental pollutants.
As described for α-HCH, the spearman rank correlation test was applied to the
data set from Schleswig-Holstein (top of Table 8.16) with the aim of checking
whether or not a correlation exists between the concentrations and the enantiomeric
ratios of the chlordane metabolites. The limitations are the same as mentioned above.
The data set from Baden-Württemberg was not large enough for this correlation test.
For oxychlordane a very strongly positive significant correlation (r s ¼ 0.92;
Fig. 8.22) and for heptachlor exoepoxide a strongly positive significant correlation
(r s ¼ 0.76; Fig. 8.23) were obtained. These values imply that higher concentration
levels of oxychlordane and heptachlor exoepoxide in the roe-deer livers may result in
a faster decomposition of the (À)-enantiomer or in a preferential formation of the
respective (+)-enantiomer. However, it should be noted that the observed correlation
is based on a consistent but small data set. Therefore, caution has to be applied when
generalising this result for other animals.
In addition to roe-deer, the long-term study carried out in the northern German
state Schleswig-Holstein also included hare (Lepus europaeus Pal.) (Rimkus and
Wolf 1987; König et al. 1994a, b, c; Pfaffenberger 1995; Hühnerfuss et al. 1996a, b).
The concentrations of α-HCH oxychlordane and heptachlor exoepoxide in hare liver
samples ranged between 10 and 100 μg/kg fat (Table 8.17), that is, within the same
order of magnitude as reported for the roe-deer liver samples discussed above.
Furthermore, the enantiomeric ratios were determined in hare liver extracts using a
1:1 mixture of OV1701/octakis(3-O-butyryl-2,6-di-O-n-pentyl)-γ-cyclodextrin
(Lipodex E) for α-HCH, and heptakis(2-O-methyl-3,6-di-O-n-pentyl)-β-cyclodextrin for oxychlordane and heptachlor exoepoxide as chiral selectors. In the case of αHCH, ER values smaller, as well as larger than one, was found, a phenomenon
which presently cannot be explained, because the data set was too small
176
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants
contamination levels of oxychlordane and heptachlor exoepoxide.
In order to gain deeper insight into the enantioselective transformation of
oxychlordane and heptachlor exoepoxide, their enantiomeric ratios (ER) were determined by enantioselective cGC. This was not possible for all samples from BadenWürttemberg (in Table 8.16 indicated with “À”) due to co-eluting matrix peaks,
which could not be sufficiently well separated by the HPLC clean-up. The assignment of the order of elution of enantiomers is based on optical rotation measurements after preparative enantiomeric resolution by packed-column GC (König et al.
1994a, b, c). In all samples, with the exception of heptachlor exoepoxide in sample
no. 1, the (À)-enantiomer was preferentially transformed. The same trend was
observed for the (À)-enantiomer of oxychlordane, where the enantiomeric discrimination appeared to be stronger in the liver samples from Baden-Württemberg than in
the samples from the region Schleswig-Holstein. By the way of contrast, the (À)enantiomer of heptachlor exoepoxide was transformed slightly stronger in the liver
samples from Schleswig-Holstein. As it cannot be expected that different enzymatic
systems are encountered in the roe-deer livers of the two German regions, other
explanations for this regional change have to be checked, for example, different
physical conditions of the animals, which in turn may be influenced by different
diseases or by stress induced by environmental pollutants.
As described for α-HCH, the spearman rank correlation test was applied to the
data set from Schleswig-Holstein (top of Table 8.16) with the aim of checking
whether or not a correlation exists between the concentrations and the enantiomeric
ratios of the chlordane metabolites. The limitations are the same as mentioned above.
The data set from Baden-Württemberg was not large enough for this correlation test.
For oxychlordane a very strongly positive significant correlation (r s ¼ 0.92;
Fig. 8.22) and for heptachlor exoepoxide a strongly positive significant correlation
(r s ¼ 0.76; Fig. 8.23) were obtained. These values imply that higher concentration
levels of oxychlordane and heptachlor exoepoxide in the roe-deer livers may result in
a faster decomposition of the (À)-enantiomer or in a preferential formation of the
respective (+)-enantiomer. However, it should be noted that the observed correlation
is based on a consistent but small data set. Therefore, caution has to be applied when
generalising this result for other animals.
In addition to roe-deer, the long-term study carried out in the northern German
state Schleswig-Holstein also included hare (Lepus europaeus Pal.) (Rimkus and
Wolf 1987; König et al. 1994a, b, c; Pfaffenberger 1995; Hühnerfuss et al. 1996a, b).
The concentrations of α-HCH oxychlordane and heptachlor exoepoxide in hare liver
samples ranged between 10 and 100 μg/kg fat (Table 8.17), that is, within the same
order of magnitude as reported for the roe-deer liver samples discussed above.
Furthermore, the enantiomeric ratios were determined in hare liver extracts using a
1:1 mixture of OV1701/octakis(3-O-butyryl-2,6-di-O-n-pentyl)-γ-cyclodextrin
(Lipodex E) for α-HCH, and heptakis(2-O-methyl-3,6-di-O-n-pentyl)-β-cyclodextrin for oxychlordane and heptachlor exoepoxide as chiral selectors. In the case of αHCH, ER values smaller, as well as larger than one, was found, a phenomenon
which presently cannot be explained, because the data set was too small
176
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants