64 Organic compounds in soils, sediments & sludges
Table 3.1 Application of supercritical fluid extraction to the determination of chlorinated insecticides
in soils.
Organochlorine
Insecticides used
Solvent used
Comments
% Recovery
Reference
DDT,Toxaphene
CO 2
Temperature/
DDT: 70%
5
pressure phase
Toxaphene: 75%
for CO 2 -DDT and
CO 2 -polychlorobiphenyls
Dichlorvos,
Subcritical
Comparison of
85%
6–9
endrin, diendrin
CO 2 with 3%
supercritical fluid
insecticide
aldehyde,
methanol
extraction, sonic
p ´
p-DDT, mirex
extraction and Soxhlet
decachlorobiphenyl
extraction
Chlordane
CO 2
Comparison of
6, 7, 10, 11
supercritical fluid
extraction, accelerated
solvent extraction and
Soxhlet extraction
Miscellaneous
CO 2 with 3%
methanol
11, 13–16
Source: Own Files.
Solid phase carbon trap has been used in conjunction with supercritical fluid
extraction liquid chromatography for the simultaneous determination of organochlorine insecticides, polychlorobiphenyls and polychlorodibenzofurans in soils [40, 41].
Chai et al [42] carried out dissipation studies of Chlorpyrifos and Acephate in
tropical soils.
Gas chromatography
There follows two examples, discussed in more detail, of gas chromatographic
methods for the determination of chlorinated insecticides in soil.
Mangani et al [25] used Carbopack B columns to recover chlorinated insecticides
in soil samples. These workers noted that the principles governing the adsorption and
extraction process in the extraction in soil analysis are the same as those that govern liquid-solid chromatography a short column is packed with the soil sample and
insecticides were desorbed from the soil by passing small columns of acetone: toluene
(1:1) through the column. Gas chromatography of the extracts was performed as follows. A glass column, 3 m long, 2 mm i.d. containing Supelcoport coated with 1.5%
SP2250 + 1,95% SP2401 was used for the analysis. The column as maintained at
200
◦ C and flow rate was 40 mL/min. This ensured complete separation of most pesticides in the test mixture. High-purity nitrogen was the carrier gas. Measurements were
obtained with dual column gas chromatograph equipped with a frequency modulated
63 Ni electron capture detector. The electron capture detector was operated in its linear
range in all cases.
In order to check different adsorption of pesticides on artificially polluted and
actually polluted soil, Mangani et al [25] prepared elution and recovery curves for the
pesticides present in an actually polluted soil sample, using a toluene: acetone mixture
Table 3.1 Application of supercritical fluid extraction to the determination of chlorinated insecticides
in soils.
Organochlorine
Insecticides used
Solvent used
Comments
% Recovery
Reference
DDT,Toxaphene
CO 2
Temperature/
DDT: 70%
5
pressure phase
Toxaphene: 75%
for CO 2 -DDT and
CO 2 -polychlorobiphenyls
Dichlorvos,
Subcritical
Comparison of
85%
6–9
endrin, diendrin
CO 2 with 3%
supercritical fluid
insecticide
aldehyde,
methanol
extraction, sonic
p ´
p-DDT, mirex
extraction and Soxhlet
decachlorobiphenyl
extraction
Chlordane
CO 2
Comparison of
6, 7, 10, 11
supercritical fluid
extraction, accelerated
solvent extraction and
Soxhlet extraction
Miscellaneous
CO 2 with 3%
methanol
11, 13–16
Source: Own Files.
Solid phase carbon trap has been used in conjunction with supercritical fluid
extraction liquid chromatography for the simultaneous determination of organochlorine insecticides, polychlorobiphenyls and polychlorodibenzofurans in soils [40, 41].
Chai et al [42] carried out dissipation studies of Chlorpyrifos and Acephate in
tropical soils.
Gas chromatography
There follows two examples, discussed in more detail, of gas chromatographic
methods for the determination of chlorinated insecticides in soil.
Mangani et al [25] used Carbopack B columns to recover chlorinated insecticides
in soil samples. These workers noted that the principles governing the adsorption and
extraction process in the extraction in soil analysis are the same as those that govern liquid-solid chromatography a short column is packed with the soil sample and
insecticides were desorbed from the soil by passing small columns of acetone: toluene
(1:1) through the column. Gas chromatography of the extracts was performed as follows. A glass column, 3 m long, 2 mm i.d. containing Supelcoport coated with 1.5%
SP2250 + 1,95% SP2401 was used for the analysis. The column as maintained at
200
◦ C and flow rate was 40 mL/min. This ensured complete separation of most pesticides in the test mixture. High-purity nitrogen was the carrier gas. Measurements were
obtained with dual column gas chromatograph equipped with a frequency modulated
63 Ni electron capture detector. The electron capture detector was operated in its linear
range in all cases.
In order to check different adsorption of pesticides on artificially polluted and
actually polluted soil, Mangani et al [25] prepared elution and recovery curves for the
pesticides present in an actually polluted soil sample, using a toluene: acetone mixture