Non-Metals
147
te peaks representing various PCB isomers were identified, the total PCB concentration in the sample amounting to 6.1 mg kg-l with much lower amounts of pesticide
residues and DDT breakdown products.
Bush and Barnard [443] analysed fish eggs by gas chromatography for 78 PCB
congeners, hexachlorobenzene, octachlorostyrene, and p,p'-DDE and mirex. Concentrations of the substances could be detected at 1 mg kg- 1 accurately using 10 mg
samples. The precision was better than ± 5 % relative standard deviation.
A gel permeation chromatography clean-up procedure has been used to determine
specified polychlorobiphenyls in fish [444] prior to analysis by capillary gas chromatography. Gel permeation chromatography gave identical results to those obtained by
the conventional saponification clean-up procedure.
Buser et al. [740] determined up to 20 tetra- to heptachloro polychlorobiphenyls or
their aryl sulphone derivates in grey seal adipose fat and liver by mass spectrometric
techniques.
Ya Ma and Bayne [760] determined polychlorinated-biphenyls in fish using linear
discrimination by electron capture negative ion chemical ionization mass spectrometry.
7.3.8
Mirex (Dechlorane, Culf,)
Markin et al. [445] have discussed the possible confusion between mirex and PCBs in
the analyses of crabs, shrimp, fish, and fish products. In their method, the samples
were thoroughly scrubbed to remove mud, algae, and other residues; they were
ground whole and mixed in a Waring blender to make a composite sample. Samples
were prepared and analysed on a whole body basis as received. A 20 g subsample of
the composite was removed and analysed as follows. The homogenized sample was
extracted with a mixture of hexane and isopropanol, and the extract subjected to a
concentrated sulphuric acid clean-up. The sulphuric acid destroys dieldrin, endrin,
and organophosphorus insecticides, but the improvement in sensitivity by this cleanup was considered more than adequate compensation for the loss of these other
insecticides. The final extract was cleaned up on a Florisil column, and concentrated
to the desired level for analysis. If PCBs were suspected in the first analysis, their
presence usually being indicated by a series of characteristic peaks, the sample was
reprocessed to separate the PCBs from the insecticides as described by Armour and
Burke [446], Gaul and Cruz-La-Grange [447], and Markin et al. [448]. After concentrating to the appropriate volume, the extract from both methods of clean-up were
chromatographed on a gas chromatograph equipped with dual electron capture detection. Each sample was analysed on two different columns: the first column was a
mixture of 1.5 % OV -17 and 1.95 % QF-l on Gas Chrom Q. The second column was
2 % DC-200 on Gas Chrom Q. Level of detection was 0.001 mg kg- 1 for DDT and its
metabolites, 0.005 mg kg- 1 for Mirex and om mg kg- 1 for Aroclor 1260.
Markin et al. [445] said that they found mirex in only a minority of the samples they
analysed, contrary to results obtained by earlier workers. All samples containing
mirex were from around Savannah, Georgia, an area with a history of concentrated
mirex use among the most extensive in the United States. The recovery of mirex in
only 12 % of the samples, all from one area, could indicate that mirex is not so general
147
te peaks representing various PCB isomers were identified, the total PCB concentration in the sample amounting to 6.1 mg kg-l with much lower amounts of pesticide
residues and DDT breakdown products.
Bush and Barnard [443] analysed fish eggs by gas chromatography for 78 PCB
congeners, hexachlorobenzene, octachlorostyrene, and p,p'-DDE and mirex. Concentrations of the substances could be detected at 1 mg kg- 1 accurately using 10 mg
samples. The precision was better than ± 5 % relative standard deviation.
A gel permeation chromatography clean-up procedure has been used to determine
specified polychlorobiphenyls in fish [444] prior to analysis by capillary gas chromatography. Gel permeation chromatography gave identical results to those obtained by
the conventional saponification clean-up procedure.
Buser et al. [740] determined up to 20 tetra- to heptachloro polychlorobiphenyls or
their aryl sulphone derivates in grey seal adipose fat and liver by mass spectrometric
techniques.
Ya Ma and Bayne [760] determined polychlorinated-biphenyls in fish using linear
discrimination by electron capture negative ion chemical ionization mass spectrometry.
7.3.8
Mirex (Dechlorane, Culf,)
Markin et al. [445] have discussed the possible confusion between mirex and PCBs in
the analyses of crabs, shrimp, fish, and fish products. In their method, the samples
were thoroughly scrubbed to remove mud, algae, and other residues; they were
ground whole and mixed in a Waring blender to make a composite sample. Samples
were prepared and analysed on a whole body basis as received. A 20 g subsample of
the composite was removed and analysed as follows. The homogenized sample was
extracted with a mixture of hexane and isopropanol, and the extract subjected to a
concentrated sulphuric acid clean-up. The sulphuric acid destroys dieldrin, endrin,
and organophosphorus insecticides, but the improvement in sensitivity by this cleanup was considered more than adequate compensation for the loss of these other
insecticides. The final extract was cleaned up on a Florisil column, and concentrated
to the desired level for analysis. If PCBs were suspected in the first analysis, their
presence usually being indicated by a series of characteristic peaks, the sample was
reprocessed to separate the PCBs from the insecticides as described by Armour and
Burke [446], Gaul and Cruz-La-Grange [447], and Markin et al. [448]. After concentrating to the appropriate volume, the extract from both methods of clean-up were
chromatographed on a gas chromatograph equipped with dual electron capture detection. Each sample was analysed on two different columns: the first column was a
mixture of 1.5 % OV -17 and 1.95 % QF-l on Gas Chrom Q. The second column was
2 % DC-200 on Gas Chrom Q. Level of detection was 0.001 mg kg- 1 for DDT and its
metabolites, 0.005 mg kg- 1 for Mirex and om mg kg- 1 for Aroclor 1260.
Markin et al. [445] said that they found mirex in only a minority of the samples they
analysed, contrary to results obtained by earlier workers. All samples containing
mirex were from around Savannah, Georgia, an area with a history of concentrated
mirex use among the most extensive in the United States. The recovery of mirex in
only 12 % of the samples, all from one area, could indicate that mirex is not so general