104–242 kJ/mol; 25–58 kcal/mol) with “a bearing on the toxicity and metabolic
interactions of these chemicals” (Kaiser 1974, Harju and Haglund 1999).
The first cGC separations of atropisomeric PCBs were published in 1993 and
1994 (König et al. 1993; Schurig and Glausch 1993; Glausch et al. 1994; Hardt et al.
1994; Wong and Garrison 2000), and in the years 1994 and 1995 the first reports on
the enantioselective determination of an atropisomeric PCB in biological samples
appeared (Hühnerfuss et al. 1994, 1995; Wong et al. 2001a, b; Ross et al. 2011a, b;
Megson et al. 2015). Meanwhile, several enantiopure or enantio-enriched
atropisomeric PCBs have been isolated by application of enantioselective HPLC
and can thus be used as standard compounds (Haglund 1995, 1996a, b; Schurig et al.
1995), for example, for the determination of the elution order of PCB atropisomers in
enantioselective cGC (Wong et al. 2001a, b, 2007).
With regard to enantioselective analysis of atropisomeric PCBs in marine and
limnic biota tissues, only few studies were reported in the literature during the past
decades. In 1994, Hühnerfuss et al. (Hardt et al. 1994; Hühnerfuss et al. 1994)
reported for the first time about the identification of five atropisomeric PCBs in blue
mussels (Mytilus edulis L.) on an achiral CP-Sil 5/C 18 CB fused-silica capillary
column (Chrompack; length 100 m). Higher levels of PCB88, PCB149, PCB174 and
PCB183 were determined in spring as compared to autumn at six sampling sites in
the Weser, Jade and Elbe river estuaries (German Bight). Furthermore, the enantiomers of PCB149 in all mussels collected during the spring and autumn period were
separated. The enantiomeric ratios ranged between 1.0 and 1.2, which implies a
weak enantio-enrichment of the first eluting enantiomer. Blanch et al. (1996) also
used enantioselective cGC for the determination of three atropisomeric PCBs in liver
samples of shark (Centroscymnus coelolepis, B. & C.). While PCB95 and PCB149
were present in racemic compositions, the second eluting enantiomer of PCB132,
that is, (+)-PCB132, predominated in most of the samples (ER ¼ 0.75–0.89). Ramos
et al. (1996) analysed nine atropisomeric PCBs in two other samples. The ERs were
in part extremely high, although the report is lacking a detailed experimental
description. Enantioenrichment of PCB149 in blubber of an adult female harbour
seal (Phoca vitulina L.) sample from Iceland was determined by Vetter et al.
(1997a, b, c, d, e, f). They report that the first eluted peak was significantly higher
than the second one. In a later study, enantioenriched PCB149 was also found in
blubber of further harbour seals, as well as grey seals (Halichoerus grypus (FABR.)),
and a Caspian seal (Phoca caspica L.) (Vetter et al. 1997a, b, c, d, e, f).
Reich et al. (1998) determined enantiomeric ratios of atropisomeric PCBs in
Mediterranean striped dolphins (Stenella coeruleoalba (ME.)). The six dolphins
were found dead along the Italian coast (Lygurian and Tirrhenian seas) in the period
1989–1990. The enantiomeric ratios (defined as relation of the first eluting enantiomer to the second one) of the nine atropisomeric PCBs (84, 91, 95, 132, 135, 136,
149, 174, 176) obtained in the samples studied revealed that PCB95 (ER ¼
0.71–1.07) PCB136 (ER ¼ 0.84–1.07), PCB174 (ER ¼ 0.58–1.16) and PCB176
(ER ¼ 0.72–0.97) were racemic or nearly racemic in almost all samples. PCB95
exhibited an enantiomeric excess (ee) of 17% of the second eluting atropisomer in
two liver samples, and PCB174 showed an ee of 26.6% in one liver sample. PCB132
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8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants
interactions of these chemicals” (Kaiser 1974, Harju and Haglund 1999).
The first cGC separations of atropisomeric PCBs were published in 1993 and
1994 (König et al. 1993; Schurig and Glausch 1993; Glausch et al. 1994; Hardt et al.
1994; Wong and Garrison 2000), and in the years 1994 and 1995 the first reports on
the enantioselective determination of an atropisomeric PCB in biological samples
appeared (Hühnerfuss et al. 1994, 1995; Wong et al. 2001a, b; Ross et al. 2011a, b;
Megson et al. 2015). Meanwhile, several enantiopure or enantio-enriched
atropisomeric PCBs have been isolated by application of enantioselective HPLC
and can thus be used as standard compounds (Haglund 1995, 1996a, b; Schurig et al.
1995), for example, for the determination of the elution order of PCB atropisomers in
enantioselective cGC (Wong et al. 2001a, b, 2007).
With regard to enantioselective analysis of atropisomeric PCBs in marine and
limnic biota tissues, only few studies were reported in the literature during the past
decades. In 1994, Hühnerfuss et al. (Hardt et al. 1994; Hühnerfuss et al. 1994)
reported for the first time about the identification of five atropisomeric PCBs in blue
mussels (Mytilus edulis L.) on an achiral CP-Sil 5/C 18 CB fused-silica capillary
column (Chrompack; length 100 m). Higher levels of PCB88, PCB149, PCB174 and
PCB183 were determined in spring as compared to autumn at six sampling sites in
the Weser, Jade and Elbe river estuaries (German Bight). Furthermore, the enantiomers of PCB149 in all mussels collected during the spring and autumn period were
separated. The enantiomeric ratios ranged between 1.0 and 1.2, which implies a
weak enantio-enrichment of the first eluting enantiomer. Blanch et al. (1996) also
used enantioselective cGC for the determination of three atropisomeric PCBs in liver
samples of shark (Centroscymnus coelolepis, B. & C.). While PCB95 and PCB149
were present in racemic compositions, the second eluting enantiomer of PCB132,
that is, (+)-PCB132, predominated in most of the samples (ER ¼ 0.75–0.89). Ramos
et al. (1996) analysed nine atropisomeric PCBs in two other samples. The ERs were
in part extremely high, although the report is lacking a detailed experimental
description. Enantioenrichment of PCB149 in blubber of an adult female harbour
seal (Phoca vitulina L.) sample from Iceland was determined by Vetter et al.
(1997a, b, c, d, e, f). They report that the first eluted peak was significantly higher
than the second one. In a later study, enantioenriched PCB149 was also found in
blubber of further harbour seals, as well as grey seals (Halichoerus grypus (FABR.)),
and a Caspian seal (Phoca caspica L.) (Vetter et al. 1997a, b, c, d, e, f).
Reich et al. (1998) determined enantiomeric ratios of atropisomeric PCBs in
Mediterranean striped dolphins (Stenella coeruleoalba (ME.)). The six dolphins
were found dead along the Italian coast (Lygurian and Tirrhenian seas) in the period
1989–1990. The enantiomeric ratios (defined as relation of the first eluting enantiomer to the second one) of the nine atropisomeric PCBs (84, 91, 95, 132, 135, 136,
149, 174, 176) obtained in the samples studied revealed that PCB95 (ER ¼
0.71–1.07) PCB136 (ER ¼ 0.84–1.07), PCB174 (ER ¼ 0.58–1.16) and PCB176
(ER ¼ 0.72–0.97) were racemic or nearly racemic in almost all samples. PCB95
exhibited an enantiomeric excess (ee) of 17% of the second eluting atropisomer in
two liver samples, and PCB174 showed an ee of 26.6% in one liver sample. PCB132
168
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants