be easily detected in the gas chromatogram of the racemate by its peak height which
is approximately twice that of the enantiomers of the chiral stereoisomers. The
enantiomers of 1,3,2
0 ,3
0 -Cl 4 BPE could be correlated by co-injection with an
enantiomerically enriched sample (40% ee), which was obtained by preceding
preparative gas chromatography of the corresponding racemate.
Although co-elution of the (S,S)-isomer of 2,3,2
0 ,3-Cl 4 BPE and the (+)enantiomer of 1,3,2
0 ,3
0 -Cl 4 BPE was encountered, a quantitative determination of
the enantiomeric proportion was possible by virtue of the specific mass spectrometric fragmentation of the isomers, using compound-specific ion traces (m/z) for the
respective selection ion monitoring (SIM). For a detailed discussion on this aspect,
the reader should refer to the report of here-discussed study (Franke et al. 1998). The
results thus obtained are summarised in Table 8.6. The enantiomeric ratios of
1,3,2
0 ,3
0 -Cl 4 BPE showed values between 0.72 and 1.20. In the samples P1, P5 and
P7 (see map in Fig. 8.9), a slight shift in the ER towards the (+)-isomer was
observed. This trend was even more obvious in the samples of September 1995. A
shift of the ER of the (À)-enantiomer to 0.72 (P5) was far beyond the medium
deviation of the experimental method. Significantly different were the proportions in
sample P9 with an increase in the ER of the (À)-enantiomer to 1.20.
The enantiomeric ratios of the 2,3,2
0 ,3
0 -Cl 4 BPE show a significant discrimination
of the (R,R)-enantiomer in the samples “Schmilka”, “Schnackenburg” and
“Seemannshöft” (February 1995), as well as in the samples of September 1995
with ER values as low as 0.27. This shift of the enantiomeric ratios in the middle part
of the Elbe River must be attributed to a decrease in the concentration of (R,R)2,3,2
0 ,3
0 -Cl 4 BPE. Due to the relatively low levels of these compounds in the series
taken in September 1995, the enantioselective discrimination and the concomitant
shift in the enantiomeric ratios can be clearly observed, since it is not superimposed
Table 8.6 Enantiomeric ratios of chiral tetrachloro bis(propyl) ethers in the River Elbe at the
stations shown in Fig. 8.10
Sample
Location
1,3,2
0 ,3
0 -Cl 4 BPE
2,3,2
0 ,3
0 -Cl 4 BPE
No
(-)/(+)
(R/R
0 )/(S,S
0 )
M/(S/S
0 )
February 1995
Bilina
1.02
0.94
1.91
P1
Schmilka
0.85
0.63
1.66
P3
Magdeburg
0.92
1.05
2.06
P5
Schnackenburg
0.89
0.78
1.87
P6
Zollenspieker
1.01
0.94
1.92
P7
Seemannshöft
0.87
0.41
1.16
P8
Grauerort
1.05
1.02
2.01
P9
Cuxhaven
1.20
1.59
2.88
September 1995
P1
Schmilka
0.86
0.54
0.74
P2
Zehren
1.00
0.83
0.83
P3
Magdeburg
0.84
0.53
1.75
P4
Tangermünde
0.82
0.44
1.42
P5
Schnackenburg
0.72
0.27
0.92
8.1 Microbial Transformation of Chiral Environmental Pollutants
127
is approximately twice that of the enantiomers of the chiral stereoisomers. The
enantiomers of 1,3,2
0 ,3
0 -Cl 4 BPE could be correlated by co-injection with an
enantiomerically enriched sample (40% ee), which was obtained by preceding
preparative gas chromatography of the corresponding racemate.
Although co-elution of the (S,S)-isomer of 2,3,2
0 ,3-Cl 4 BPE and the (+)enantiomer of 1,3,2
0 ,3
0 -Cl 4 BPE was encountered, a quantitative determination of
the enantiomeric proportion was possible by virtue of the specific mass spectrometric fragmentation of the isomers, using compound-specific ion traces (m/z) for the
respective selection ion monitoring (SIM). For a detailed discussion on this aspect,
the reader should refer to the report of here-discussed study (Franke et al. 1998). The
results thus obtained are summarised in Table 8.6. The enantiomeric ratios of
1,3,2
0 ,3
0 -Cl 4 BPE showed values between 0.72 and 1.20. In the samples P1, P5 and
P7 (see map in Fig. 8.9), a slight shift in the ER towards the (+)-isomer was
observed. This trend was even more obvious in the samples of September 1995. A
shift of the ER of the (À)-enantiomer to 0.72 (P5) was far beyond the medium
deviation of the experimental method. Significantly different were the proportions in
sample P9 with an increase in the ER of the (À)-enantiomer to 1.20.
The enantiomeric ratios of the 2,3,2
0 ,3
0 -Cl 4 BPE show a significant discrimination
of the (R,R)-enantiomer in the samples “Schmilka”, “Schnackenburg” and
“Seemannshöft” (February 1995), as well as in the samples of September 1995
with ER values as low as 0.27. This shift of the enantiomeric ratios in the middle part
of the Elbe River must be attributed to a decrease in the concentration of (R,R)2,3,2
0 ,3
0 -Cl 4 BPE. Due to the relatively low levels of these compounds in the series
taken in September 1995, the enantioselective discrimination and the concomitant
shift in the enantiomeric ratios can be clearly observed, since it is not superimposed
Table 8.6 Enantiomeric ratios of chiral tetrachloro bis(propyl) ethers in the River Elbe at the
stations shown in Fig. 8.10
Sample
Location
1,3,2
0 ,3
0 -Cl 4 BPE
2,3,2
0 ,3
0 -Cl 4 BPE
No
(-)/(+)
(R/R
0 )/(S,S
0 )
M/(S/S
0 )
February 1995
Bilina
1.02
0.94
1.91
P1
Schmilka
0.85
0.63
1.66
P3
Magdeburg
0.92
1.05
2.06
P5
Schnackenburg
0.89
0.78
1.87
P6
Zollenspieker
1.01
0.94
1.92
P7
Seemannshöft
0.87
0.41
1.16
P8
Grauerort
1.05
1.02
2.01
P9
Cuxhaven
1.20
1.59
2.88
September 1995
P1
Schmilka
0.86
0.54
0.74
P2
Zehren
1.00
0.83
0.83
P3
Magdeburg
0.84
0.53
1.75
P4
Tangermünde
0.82
0.44
1.42
P5
Schnackenburg
0.72
0.27
0.92
8.1 Microbial Transformation of Chiral Environmental Pollutants
127