ion monitoring (SIM), which allowed a substantially improved selective detection of
the target compounds (Fig. 8.25).
In all liver sample extracts investigated by Ellerichmann et al. (1998a, b, c),
exclusively the second eluting enantiomers of the MeSO 2 -PCBs 3-149 and 3-132
were encountered, that is, not only a high congener selective (as already previously
observed), but also a high enantioselective liver retention of these MeSO 2 -PCBs was
determined. None of the MeSO 2 -PCBs included in the study by Ellerichmann et al.
were detected in the two human lung samples (Ellerichmann et al. 1998a, b, c).
In the here-reported joint Swedish/German investigation, the enantiomeric
excesses of selected chiral methylsulphonyl PCBs in liver and adipose tissues
from rats dosed with Clophen A50 were determined (Larsson et al. 1999, 2002).
Rats were given one single oral dose of the commercial PCB product Clophen A50
dissolved in corn oil (25 mg/kg b.w.). The rats were sacrificed after 1, 2, 4 and
8 weeks and the liver, lung, kidney, adrenal gland and fat were removed and kept
frozen until the analysis. In all samples analysed, the concentrations of the 4-MeSO 2 -
CB91 and 4
0 -MeSO 2 -CB132 were slightly higher than those of the 3-MeSO 2 -PCB
isomers in fat and liver. But still the ratio 4-MeSO 2 -PCBs/3-MeSO 2 -PCBs was
almost 1:1 for these MeSO 2 -PCB congeners in both liver and fat. It is important to
note that comparable enantiomeric ratios were found in fat and liver tissue extracts:
in all samples analysed by Larsson et al. (2002), only the second eluting enantiomers
of 3
0 -MeSO 2 -CB132 and 3-MeSO 2 -CB149 were present (Fig. 8.26). In contrast,
4-MeSO 2 -CB91, 4
0 -MeSO 2 -CB132 and 4-MeSO 2 -CB149 were dominated by the
first eluting enantiomers, although minor amounts of the second eluting enantiomers
were also found. The ratios of the first and second eluting enantiomers (the quotient
a/b) for 4-MeSO 2 -CB91 were in the range 7–11, for 4-MeSO 2 -CB149 2-8 and for
3
0 -MeSO 2 -CB132 6-13. This indicates that either both enantiomers are being formed
or, if only one enantiomer is formed, that this enantiomer is converted to both optical
forms. This is true at least for the 4-MeSO 2 -PCBs. For the 3-MeSO 2 -PCBs, there
were no indications of another enantiomer. Furthermore, it cannot be excluded that
enantioselective transport processes may also play an additional role.
Larsson et al. (2002) reported unusual results on enantiomeric excesses of
MeSO 2 -PCBs in rat lung sample extracts, determined for the same animals the
adipose and liver tissues of whom had been analysed. Changes in the enantiomer
fractions (EFs) of the MeSO 2 -PCB atropisomers after exposure were also determined. For this investigation, liver, lung and adipose tissue from rats exposed to
Clophen A50 were analysed for the MeSO 2 -PCB atropisomers of 3-methylsulfonyl2,2
0 ,4
0 ,5,6-pentachlorobiphenyl (5-MeSO 2 -CB91), 4-methylsulfonyl-2,2
0 ,3,4
0 ,6pentachlorobiphenyl
(4-MeSO 2 -CB91),
3-methylsulfonyl-2,2
0 ,3
0 ,4
0 ,5,6hexachlorobiphenyl
(5
0 -MeSO2-CB132),
4-methylsulfonyl-2,2
0 ,3,3
0 ,4
0 ,6hexachlorobiphenyl
(4
0 -MeSO 2 -CB132),
3-methylsulfonyl-2,2
0 ,4
0 ,5,5
0 ,6hexachlorobiphenyl (5-MeSO 2 -CB149) and 4-methylsulfonyl-2,2
0 ,3,4
0 ,5
0 ,6hexachlorobiphenyl (4-MeSO 2 -CB149). The authors found that especially for the
lung, the para-MeSO 2 -PCBs were more abundant than the meta-MeSO 2 -PCBs. The
concentration ratio for the atropisomers analysed was higher for 4-MeSO 2 -CB149
versus 5-MeSO 2 -CB149 than for the corresponding ratio 4-/5-MeSO 2 -CB91 and 4
0 -/
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
183
the target compounds (Fig. 8.25).
In all liver sample extracts investigated by Ellerichmann et al. (1998a, b, c),
exclusively the second eluting enantiomers of the MeSO 2 -PCBs 3-149 and 3-132
were encountered, that is, not only a high congener selective (as already previously
observed), but also a high enantioselective liver retention of these MeSO 2 -PCBs was
determined. None of the MeSO 2 -PCBs included in the study by Ellerichmann et al.
were detected in the two human lung samples (Ellerichmann et al. 1998a, b, c).
In the here-reported joint Swedish/German investigation, the enantiomeric
excesses of selected chiral methylsulphonyl PCBs in liver and adipose tissues
from rats dosed with Clophen A50 were determined (Larsson et al. 1999, 2002).
Rats were given one single oral dose of the commercial PCB product Clophen A50
dissolved in corn oil (25 mg/kg b.w.). The rats were sacrificed after 1, 2, 4 and
8 weeks and the liver, lung, kidney, adrenal gland and fat were removed and kept
frozen until the analysis. In all samples analysed, the concentrations of the 4-MeSO 2 -
CB91 and 4
0 -MeSO 2 -CB132 were slightly higher than those of the 3-MeSO 2 -PCB
isomers in fat and liver. But still the ratio 4-MeSO 2 -PCBs/3-MeSO 2 -PCBs was
almost 1:1 for these MeSO 2 -PCB congeners in both liver and fat. It is important to
note that comparable enantiomeric ratios were found in fat and liver tissue extracts:
in all samples analysed by Larsson et al. (2002), only the second eluting enantiomers
of 3
0 -MeSO 2 -CB132 and 3-MeSO 2 -CB149 were present (Fig. 8.26). In contrast,
4-MeSO 2 -CB91, 4
0 -MeSO 2 -CB132 and 4-MeSO 2 -CB149 were dominated by the
first eluting enantiomers, although minor amounts of the second eluting enantiomers
were also found. The ratios of the first and second eluting enantiomers (the quotient
a/b) for 4-MeSO 2 -CB91 were in the range 7–11, for 4-MeSO 2 -CB149 2-8 and for
3
0 -MeSO 2 -CB132 6-13. This indicates that either both enantiomers are being formed
or, if only one enantiomer is formed, that this enantiomer is converted to both optical
forms. This is true at least for the 4-MeSO 2 -PCBs. For the 3-MeSO 2 -PCBs, there
were no indications of another enantiomer. Furthermore, it cannot be excluded that
enantioselective transport processes may also play an additional role.
Larsson et al. (2002) reported unusual results on enantiomeric excesses of
MeSO 2 -PCBs in rat lung sample extracts, determined for the same animals the
adipose and liver tissues of whom had been analysed. Changes in the enantiomer
fractions (EFs) of the MeSO 2 -PCB atropisomers after exposure were also determined. For this investigation, liver, lung and adipose tissue from rats exposed to
Clophen A50 were analysed for the MeSO 2 -PCB atropisomers of 3-methylsulfonyl2,2
0 ,4
0 ,5,6-pentachlorobiphenyl (5-MeSO 2 -CB91), 4-methylsulfonyl-2,2
0 ,3,4
0 ,6pentachlorobiphenyl
(4-MeSO 2 -CB91),
3-methylsulfonyl-2,2
0 ,3
0 ,4
0 ,5,6hexachlorobiphenyl
(5
0 -MeSO2-CB132),
4-methylsulfonyl-2,2
0 ,3,3
0 ,4
0 ,6hexachlorobiphenyl
(4
0 -MeSO 2 -CB132),
3-methylsulfonyl-2,2
0 ,4
0 ,5,5
0 ,6hexachlorobiphenyl (5-MeSO 2 -CB149) and 4-methylsulfonyl-2,2
0 ,3,4
0 ,5
0 ,6hexachlorobiphenyl (4-MeSO 2 -CB149). The authors found that especially for the
lung, the para-MeSO 2 -PCBs were more abundant than the meta-MeSO 2 -PCBs. The
concentration ratio for the atropisomers analysed was higher for 4-MeSO 2 -CB149
versus 5-MeSO 2 -CB149 than for the corresponding ratio 4-/5-MeSO 2 -CB91 and 4
0 -/
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
183