Organics
223
9.4.5
Chlorinated Insecticides
Sodergren [636] used digestion with fuming sulphuric acid to clean up samples prior
to the determination of chlorinated insecticides in algae by gas chromatography. A
hexane extract of the sample is concentrated to 350 !ll and 50 !ll is sealed in a glass
tube with 50 !ll offuming sulphuric acid (10 ~ S03)' After mixing, the phases are then
separated and the hexane layer is subjected to gas chromatography. A second portion
of the original extract is mixed with an equal volume of 5 % propanolic potassium
hydroxide in a special pipette, which is sealed and heated in a water bath for 10 min.
After heating, 5 ml of water is added and, after further mixing, the hexane fraction is
allowed to separate for analysis. The remainder of the original extract is evaporated,
and the residue of extractable lipids is weighed. Sample recoveries are 78-94 %, losses
occurring mainly in the extraction stage.
Sodergren [637] investigated the simultaneous detection of PCBs, chlorinated insecticides, and other compounds by electron capture and flame ionization detectors
combined in series using an open tube capillary column. He combined the electron
capture detector and flame ionization detection in series to obtain a dual detection
system capable of simultaneous detection of environmental pollutants of different
character, e. g. organochlorine residues and the oil and lipid constituents in samples
from aquatic environments. In order that the limit of detection should not be adversely affected when using capillary columns, a splitless system without a scavenging gas
was used. Since electron capture is a non-destructive process, the effluent from the
column passes undisturbed through the electron capture detector. The effluent was
then directed to the jet-tip of the flame ionization detector by means of a glass
capillary tube. With capillary columns, a minimum flow rate of 1.9 ml min- 1 was
required to operate the electron capture detector. The flows of hydrogen and air to the
flame ionization detector were around 25 and 250 ml min- 1 respectively.
Organochlorine insecticides and methyl esters of fatty acids were detected simultaneously using this system. Sodergren [637] used his detection system to study the
degradation and fate of persistent pollutants in aquatic model ecosystems. Usually
these pollutants are closely associated with lipids. Therefore, it is an advantage to be
able to study the occurrence and amount of both lipids and, for example, organochlorine residues. A cell extract from a continuous flow culture of the green alga Chlorella
pyrenoidosa, to which polychlorinated biphenyls had been added, was hydrolysed by
treatment with a solution of acetyl chloride in methanol and then presented to the
detection system. The PCBs added to the culture were efficiently taken up by the algal
cells: the lipids detected in the extract were palmitic acid and stearic acid. Lipids and
substances of lipophilic character tend to accumulate in aquatic environments at the
interface between water and air. To assess the ability of the electron capture flame
ionization detector system to detect mineral oil and PCBs simultaneously, a mixture
of these substances was injected into the water of an aquarium below the surface. The
surface fUm thus created was sampled [357], extracted, and an aliquot of the extract
injected into the gas chromatograph equipped with a capillary column and a low
volume electron capture detector and flame ionization detector. The mineral oil was
eluted before the main PCB components appeared. Due to the high sensitivity of the
223
9.4.5
Chlorinated Insecticides
Sodergren [636] used digestion with fuming sulphuric acid to clean up samples prior
to the determination of chlorinated insecticides in algae by gas chromatography. A
hexane extract of the sample is concentrated to 350 !ll and 50 !ll is sealed in a glass
tube with 50 !ll offuming sulphuric acid (10 ~ S03)' After mixing, the phases are then
separated and the hexane layer is subjected to gas chromatography. A second portion
of the original extract is mixed with an equal volume of 5 % propanolic potassium
hydroxide in a special pipette, which is sealed and heated in a water bath for 10 min.
After heating, 5 ml of water is added and, after further mixing, the hexane fraction is
allowed to separate for analysis. The remainder of the original extract is evaporated,
and the residue of extractable lipids is weighed. Sample recoveries are 78-94 %, losses
occurring mainly in the extraction stage.
Sodergren [637] investigated the simultaneous detection of PCBs, chlorinated insecticides, and other compounds by electron capture and flame ionization detectors
combined in series using an open tube capillary column. He combined the electron
capture detector and flame ionization detection in series to obtain a dual detection
system capable of simultaneous detection of environmental pollutants of different
character, e. g. organochlorine residues and the oil and lipid constituents in samples
from aquatic environments. In order that the limit of detection should not be adversely affected when using capillary columns, a splitless system without a scavenging gas
was used. Since electron capture is a non-destructive process, the effluent from the
column passes undisturbed through the electron capture detector. The effluent was
then directed to the jet-tip of the flame ionization detector by means of a glass
capillary tube. With capillary columns, a minimum flow rate of 1.9 ml min- 1 was
required to operate the electron capture detector. The flows of hydrogen and air to the
flame ionization detector were around 25 and 250 ml min- 1 respectively.
Organochlorine insecticides and methyl esters of fatty acids were detected simultaneously using this system. Sodergren [637] used his detection system to study the
degradation and fate of persistent pollutants in aquatic model ecosystems. Usually
these pollutants are closely associated with lipids. Therefore, it is an advantage to be
able to study the occurrence and amount of both lipids and, for example, organochlorine residues. A cell extract from a continuous flow culture of the green alga Chlorella
pyrenoidosa, to which polychlorinated biphenyls had been added, was hydrolysed by
treatment with a solution of acetyl chloride in methanol and then presented to the
detection system. The PCBs added to the culture were efficiently taken up by the algal
cells: the lipids detected in the extract were palmitic acid and stearic acid. Lipids and
substances of lipophilic character tend to accumulate in aquatic environments at the
interface between water and air. To assess the ability of the electron capture flame
ionization detector system to detect mineral oil and PCBs simultaneously, a mixture
of these substances was injected into the water of an aquarium below the surface. The
surface fUm thus created was sampled [357], extracted, and an aliquot of the extract
injected into the gas chromatograph equipped with a capillary column and a low
volume electron capture detector and flame ionization detector. The mineral oil was
eluted before the main PCB components appeared. Due to the high sensitivity of the