146
Fish
determination of the total DDT content. The content of PCBs can be calculated in the
,derivatization' gas chromatogram without interference effects due to saturated DDT
metabolites.
Norheim and Okland [432] studied the distribution of down to 0.001 mg kg-I
persistant chlorinated insecticides, such as DDT, polychlorinated biphenyls and hexachlorobenzene, in cod samples taken along the Norwegian coast.
In their analytical procedure, a 0.5 g sample of fish was digested with 6 ml concentrated sulphuric acid for 4 h at 60°C. The cooled digest was shaken with 1 ml hexane
and this extract examined by electron capture gas chromatography. Recoveries of
95 % of added hexachlorobenzene and octachlorostyrene were obtained in spiking
experiments. Good interlaboratory comparison was obtained in determinations of
hexachlorobenzene, octachlorostyrene and pentachlorobenzene, present at 0.0014 mg kg-I levels in fish.
Neeley [433] determined PCBs in fish and water in lake Michigan whilst Frederick
[434] measured, by gas chromatography, the comparative uptake of PCBs and dieldrin by the white sucker. Jan and Malservic [435] determined PCBs and polychlorinated terphenyls in fish using acid hydrolysis of the fish tissue and destructive clean-up
of the extract. Olsson et al. [436] studied the seasonal variation of PCB levels in roach.
Szelewski et al. [437] have also determined PCBs in fish samples.
Gaskin et al. [438] have described a gas chromatographic method for determining
DDT, dieldrin and PCBs in the organs of whales and dolphins. Total DDT in blubbers
ranged from 1.25 to 7.4 mg kg-I, dieldrin in blubber from 0.007 to 0.04 mg kg-I and
PCB in blubber from 0.69 to 5.0 mg kg-I.
Ludke and Schmitt [439] have reported on pesticide and polychlorobiphenyl concentrations found in fish in the US National Pesticide Monitoring Programme.
7.3.7
Polychlorinated Biphenyls
Sackmauer et al. [440] determined PCBs in water and fish by thin-layer chromatography on silica gel plates impregnated with 8 % paraffin oil. As a mobile phase, a
mixture of acetonitrile, acetone, methanol and water (20: 9: 20: 1) was used. For
detection, a solution of silver nitrate and 2-phenoxyethanol was used, followed by
irradiation with UV light. The detection sensitivity for Aroclor 1242 is 0.5-1.0 I1g.
Szelewski et al. [441] claim that some loss of PCB homologues occurs during the
chromium trioxide extraction of fish tissue. The biphenylfree PCB extract is then
perchlorinated using antimony pentachloride in a special apparatus at 200°C. Following acidification and toluene extraction, the aqueous phase remaining is extracted
with hexane, and this extract passed down an anhydrous sodium sulphate microcolumn and concentrated in Kuderna Danish evaporator prior to gas chromatography.
Comparison of the gas chromatograms of the polychlorobiphenyls thus obtained with
those obtained for the perchlorination product of an authentic sample of PCB (e. g.
Aroclor 1260) enables identifications to be made of the types of PCBs in the sample
extract.
Tausch et al. [442] determined polychlorobiphenyls in fish taken from the Danube
river, by capillary gas chromatography and mass spectrometry. Altogether, 40 separa-
Fish
determination of the total DDT content. The content of PCBs can be calculated in the
,derivatization' gas chromatogram without interference effects due to saturated DDT
metabolites.
Norheim and Okland [432] studied the distribution of down to 0.001 mg kg-I
persistant chlorinated insecticides, such as DDT, polychlorinated biphenyls and hexachlorobenzene, in cod samples taken along the Norwegian coast.
In their analytical procedure, a 0.5 g sample of fish was digested with 6 ml concentrated sulphuric acid for 4 h at 60°C. The cooled digest was shaken with 1 ml hexane
and this extract examined by electron capture gas chromatography. Recoveries of
95 % of added hexachlorobenzene and octachlorostyrene were obtained in spiking
experiments. Good interlaboratory comparison was obtained in determinations of
hexachlorobenzene, octachlorostyrene and pentachlorobenzene, present at 0.0014 mg kg-I levels in fish.
Neeley [433] determined PCBs in fish and water in lake Michigan whilst Frederick
[434] measured, by gas chromatography, the comparative uptake of PCBs and dieldrin by the white sucker. Jan and Malservic [435] determined PCBs and polychlorinated terphenyls in fish using acid hydrolysis of the fish tissue and destructive clean-up
of the extract. Olsson et al. [436] studied the seasonal variation of PCB levels in roach.
Szelewski et al. [437] have also determined PCBs in fish samples.
Gaskin et al. [438] have described a gas chromatographic method for determining
DDT, dieldrin and PCBs in the organs of whales and dolphins. Total DDT in blubbers
ranged from 1.25 to 7.4 mg kg-I, dieldrin in blubber from 0.007 to 0.04 mg kg-I and
PCB in blubber from 0.69 to 5.0 mg kg-I.
Ludke and Schmitt [439] have reported on pesticide and polychlorobiphenyl concentrations found in fish in the US National Pesticide Monitoring Programme.
7.3.7
Polychlorinated Biphenyls
Sackmauer et al. [440] determined PCBs in water and fish by thin-layer chromatography on silica gel plates impregnated with 8 % paraffin oil. As a mobile phase, a
mixture of acetonitrile, acetone, methanol and water (20: 9: 20: 1) was used. For
detection, a solution of silver nitrate and 2-phenoxyethanol was used, followed by
irradiation with UV light. The detection sensitivity for Aroclor 1242 is 0.5-1.0 I1g.
Szelewski et al. [441] claim that some loss of PCB homologues occurs during the
chromium trioxide extraction of fish tissue. The biphenylfree PCB extract is then
perchlorinated using antimony pentachloride in a special apparatus at 200°C. Following acidification and toluene extraction, the aqueous phase remaining is extracted
with hexane, and this extract passed down an anhydrous sodium sulphate microcolumn and concentrated in Kuderna Danish evaporator prior to gas chromatography.
Comparison of the gas chromatograms of the polychlorobiphenyls thus obtained with
those obtained for the perchlorination product of an authentic sample of PCB (e. g.
Aroclor 1260) enables identifications to be made of the types of PCBs in the sample
extract.
Tausch et al. [442] determined polychlorobiphenyls in fish taken from the Danube
river, by capillary gas chromatography and mass spectrometry. Altogether, 40 separa-