154 Organic compounds in soils, sediments & sludges
sulphur was examined. Recoveries at the ug
−1 kg level were 54.6–82.4%. Detection
limits were 95–220 ug kg
−1 .
The supercritical carbon dioxide extraction procedure [39] has also been applied
with ≤85% recovery to the recovery of organophosphorus insecticides from sediments.
Compounds studied included Parathon ethyl, Methidathion and Tetrachlorovinphos.
Grob et al [163] compare supercritical extraction with classic sonication and
Soxhlet extraction from river sediments for selected organophosphorus insecticides
including Diazinon, Ronnel, Parathion ethyl, Methidathion and Tetrachlorovinphos.
Samples were extracted with supercritical carbon dioxide modified with 3% methyl
alcohol at 350
◦ C atmosphere and 50
◦ C gave a recovery of at least 85%.
6.7.2 Organochlorine insecticides
Wegmann and Hafster et al [119] have developed a capillary gas chromatographic
method for the determination of organochlorine insecticides in river sediments. Bottom
soils from rivers, collected in slow current area may contain high concentrations of
organochlorine insecticides and polychlorobiphenyls. When the current moves more
rapidly or benthic animals become more active, these compounds are stirred into the
water along with suspended particles and become accessible to organisms that live in
the bottom layer.
Bottom soil is quite different from soil on land, particularly if it is collected from
an anaerobic zone. Bottom soil specimens also have varying composition. The presence
of elementary sulphur and organic compounds of sulphur greatly complicates analysis
of the residual organochlorine insecticides and polychlorobiphenyls, rapidly poisoning
the packing of chromatographic columns. It is completely impossible to determine the
isomers of HCCH, hexachlorobenzene, Aldrin and Heptachlor in unpurified bottom
soil extracts. Raw bottom soil extracts are treated with highly purified copper power
or metallic mercury to facilitate analysis or are sulphurised with sodium sulphate in
the presence of tetrabutyl ammonium sulphate [165] with mercury recovery by sediment extraction ranging from 69% for Heptachlor epoxide to 97% for Arochlor 1254
and used with copper recoveries ranted from 5% for Heptachlor up to 10% for
Arochlor 1254.
The method for analysing sediment involves extraction of organochlorine insecticides and polychlorobiphenyls with a mixture of acetone and hexane together with
1% aqueous ammonium chloride. The extracts are then concentrated for purification with concentrated sulphuric acid and aqueous sodium sulphite in the presence of
tetrabutylammonium sulphate and finally gas chromatographic analysis is applied.
The minimum detectable quantities are: HCCH isomers – 0.01 ng; 4,4’-DDE (n, n’DDE) −0.05 ng; 4,4’-DDD (n, n’-DDD) −0.01 ng; 4,4’-DDT (n, n’-DDT) −0.20 ng;
and PCB (Chlophen A-50) −1.0 ng.
Jensen et al [166, 168] and others [167] also discuss complications in analysis
due to the presence of elementary sulphur and organosulphur compounds in the gas
chromatographic determination of DDT and polychlorobiphenyls in sediments and
sewage sludges.
The method can also be used for a search for both volatile and/or polar pollutants.
The sulphur interfering in the gas chromatographic determination is removed in a nondestructive treatment of the extract with tetrabutylammonium sulphite. This lipophilic
sulphur was examined. Recoveries at the ug
−1 kg level were 54.6–82.4%. Detection
limits were 95–220 ug kg
−1 .
The supercritical carbon dioxide extraction procedure [39] has also been applied
with ≤85% recovery to the recovery of organophosphorus insecticides from sediments.
Compounds studied included Parathon ethyl, Methidathion and Tetrachlorovinphos.
Grob et al [163] compare supercritical extraction with classic sonication and
Soxhlet extraction from river sediments for selected organophosphorus insecticides
including Diazinon, Ronnel, Parathion ethyl, Methidathion and Tetrachlorovinphos.
Samples were extracted with supercritical carbon dioxide modified with 3% methyl
alcohol at 350
◦ C atmosphere and 50
◦ C gave a recovery of at least 85%.
6.7.2 Organochlorine insecticides
Wegmann and Hafster et al [119] have developed a capillary gas chromatographic
method for the determination of organochlorine insecticides in river sediments. Bottom
soils from rivers, collected in slow current area may contain high concentrations of
organochlorine insecticides and polychlorobiphenyls. When the current moves more
rapidly or benthic animals become more active, these compounds are stirred into the
water along with suspended particles and become accessible to organisms that live in
the bottom layer.
Bottom soil is quite different from soil on land, particularly if it is collected from
an anaerobic zone. Bottom soil specimens also have varying composition. The presence
of elementary sulphur and organic compounds of sulphur greatly complicates analysis
of the residual organochlorine insecticides and polychlorobiphenyls, rapidly poisoning
the packing of chromatographic columns. It is completely impossible to determine the
isomers of HCCH, hexachlorobenzene, Aldrin and Heptachlor in unpurified bottom
soil extracts. Raw bottom soil extracts are treated with highly purified copper power
or metallic mercury to facilitate analysis or are sulphurised with sodium sulphate in
the presence of tetrabutyl ammonium sulphate [165] with mercury recovery by sediment extraction ranging from 69% for Heptachlor epoxide to 97% for Arochlor 1254
and used with copper recoveries ranted from 5% for Heptachlor up to 10% for
Arochlor 1254.
The method for analysing sediment involves extraction of organochlorine insecticides and polychlorobiphenyls with a mixture of acetone and hexane together with
1% aqueous ammonium chloride. The extracts are then concentrated for purification with concentrated sulphuric acid and aqueous sodium sulphite in the presence of
tetrabutylammonium sulphate and finally gas chromatographic analysis is applied.
The minimum detectable quantities are: HCCH isomers – 0.01 ng; 4,4’-DDE (n, n’DDE) −0.05 ng; 4,4’-DDD (n, n’-DDD) −0.01 ng; 4,4’-DDT (n, n’-DDT) −0.20 ng;
and PCB (Chlophen A-50) −1.0 ng.
Jensen et al [166, 168] and others [167] also discuss complications in analysis
due to the presence of elementary sulphur and organosulphur compounds in the gas
chromatographic determination of DDT and polychlorobiphenyls in sediments and
sewage sludges.
The method can also be used for a search for both volatile and/or polar pollutants.
The sulphur interfering in the gas chromatographic determination is removed in a nondestructive treatment of the extract with tetrabutylammonium sulphite. This lipophilic