142
Fish
A bullhead catfish from a pristine area (resort lake, no industry, agricultural)
(Fig. 7.2) had a total polyaromatic hydrocarbon content of about 38 Jlg kg-I, and the
individual compounds are around 5 Jlg- I .
Birkholz et al. [408] have described a method for the extraction, cleanup, and high
resolution gas chromatographic analysis of polycyclic aromatic hydrocarbons, polycyclic aromatic sulphur heterocycles, and basic polycyclic aromatic nitrogen heterocycles in fish. Soxhlet extraction of fish tissue with methylene chloride was followed
by gel permeation chromatography using Bio-beads SX-3.
For polyaromatic hydrocarbons and polycyclic aromatic sulphur heterocycles,
cleanup was by absorption chromatography on florisil and elution with hexane. Basic
polycyclic aromatic nitrogen heterocycles cleanup was by partitioning with hydrochloric acid and chloroform, increasing the pH to 11 with sodium hydroxide and
extracting with chloroform. Samples were analysed using capillary gas chromatography with flame ionization detection or with mass spectrometry. Similar results were
obtained with the two methods. Average recoveries for these three classes of compounds were 87, 70 and 97 % from fish tissue fortified at 0.24-1.1, 0.024-0.11 and
1.2-1.4 mg kg-I respectively.
Ariese et al. [758] applied chemical derivativization with methyliodide and Shpol'skii spectrofluorimetry to the determination of benzo (a) pyrene in amounts down to
0.005 mg moll-I in flounder fish bile.
7.3.3
Phthalate Esters
Giam et al. [409] determined phthalate esters in amounts down to less than 5 Jlg kg-I
in marine fish using capillary column gas chromatography with an electron capture
detector. Chlorinated insecticides and chlorinated biphenyls interfere in this chromatographic analysis and consequently have first to be removed by column chromatography on water deactivated florisil.
The tissue was macerated with acetonitrile, then diluted with methylene chloridepetroleum ether (1 : 5) and extracted with salt water. The dried organic phase was
concentrated and diluted with iso-octane and subjected to clean-up in a florisil
column. Elution of the florisil column with 6 %, then 15 %, then 20 % diethyl ether in
petroleum ether provided three fractions containing, respectively,
(i) chlorinated insecticides and chlorinated biphenyls, (ii) diethylhexylphthalate and
dibutylphthalate, and (iii) dibutylphthalate.
Extreme precautions are necessary in this procedure to avoid contamination due to
phthalates present as impurities in commonly used laboratory materials, e. g. aluminium foil contains 300 mg kg-I phthalate.
Between 2 and 20 Jlg kg-I of diethylhexyl phthalate was found by this procedure in
various types of fish taken in the Gulf of Mexico.
7.3.4
Chlorinated Aliphatic Hydrocarbons
Various workers have discussed the application of gas chromatography to the determination of chlorinated aliphatics in fish [330-336]. Compounds that have been
Fish
A bullhead catfish from a pristine area (resort lake, no industry, agricultural)
(Fig. 7.2) had a total polyaromatic hydrocarbon content of about 38 Jlg kg-I, and the
individual compounds are around 5 Jlg- I .
Birkholz et al. [408] have described a method for the extraction, cleanup, and high
resolution gas chromatographic analysis of polycyclic aromatic hydrocarbons, polycyclic aromatic sulphur heterocycles, and basic polycyclic aromatic nitrogen heterocycles in fish. Soxhlet extraction of fish tissue with methylene chloride was followed
by gel permeation chromatography using Bio-beads SX-3.
For polyaromatic hydrocarbons and polycyclic aromatic sulphur heterocycles,
cleanup was by absorption chromatography on florisil and elution with hexane. Basic
polycyclic aromatic nitrogen heterocycles cleanup was by partitioning with hydrochloric acid and chloroform, increasing the pH to 11 with sodium hydroxide and
extracting with chloroform. Samples were analysed using capillary gas chromatography with flame ionization detection or with mass spectrometry. Similar results were
obtained with the two methods. Average recoveries for these three classes of compounds were 87, 70 and 97 % from fish tissue fortified at 0.24-1.1, 0.024-0.11 and
1.2-1.4 mg kg-I respectively.
Ariese et al. [758] applied chemical derivativization with methyliodide and Shpol'skii spectrofluorimetry to the determination of benzo (a) pyrene in amounts down to
0.005 mg moll-I in flounder fish bile.
7.3.3
Phthalate Esters
Giam et al. [409] determined phthalate esters in amounts down to less than 5 Jlg kg-I
in marine fish using capillary column gas chromatography with an electron capture
detector. Chlorinated insecticides and chlorinated biphenyls interfere in this chromatographic analysis and consequently have first to be removed by column chromatography on water deactivated florisil.
The tissue was macerated with acetonitrile, then diluted with methylene chloridepetroleum ether (1 : 5) and extracted with salt water. The dried organic phase was
concentrated and diluted with iso-octane and subjected to clean-up in a florisil
column. Elution of the florisil column with 6 %, then 15 %, then 20 % diethyl ether in
petroleum ether provided three fractions containing, respectively,
(i) chlorinated insecticides and chlorinated biphenyls, (ii) diethylhexylphthalate and
dibutylphthalate, and (iii) dibutylphthalate.
Extreme precautions are necessary in this procedure to avoid contamination due to
phthalates present as impurities in commonly used laboratory materials, e. g. aluminium foil contains 300 mg kg-I phthalate.
Between 2 and 20 Jlg kg-I of diethylhexyl phthalate was found by this procedure in
various types of fish taken in the Gulf of Mexico.
7.3.4
Chlorinated Aliphatic Hydrocarbons
Various workers have discussed the application of gas chromatography to the determination of chlorinated aliphatics in fish [330-336]. Compounds that have been