Organics
203
de in marine organisms. These substances were separated and determined on a glass
column (4 m x 4 mm) packed with 3 % of SE-52 on Chromosorb W (AW DMCS) (80
to 100-mesh) and operated at 35°C, with argon (30 ml min-I) as carrier gas. An
electron capture detector was used, with argon-methane (9:1) as quench gas. A
limitation of this procedure is that compounds which boil considerably above 100°C
could not be determined.
8.2.4
Chlorinated Insecticides
Gas Chromatography. The determination of chlorinated insecticides in crustacea has
been discussed by several workers [581-589]. Mills et al. [581] dehydrated oyster
samples by mixing them with a 9: 1 mixture of anhydrous sodium sulphate and Quso
(a micro-fine silica). They could be held at room temperature for up to 15 days
without loss or degradation of chlorinated insecticides. The tissues of oysters were
homogenized. Approximately 30 g of the homogenate was added to a second Mason
jar and blended with a 9:1 mixture of sodium sulphate and Quso. By alternately
chilling and blending, a free-flowing powder was obtained. The blended sample was
wrapped in aluminium foil and shipped to the laboratory. Upon receipt of the sample,
it was weighed and extracted in a Soxhlet apparatus for 4 h with petroleum ether. The
extracts were then purified by concentrating and transferring the extract to separatory funnels. The extracts were diluted to 25 ml with petroleum ether and partitioned
with two 50 ml portions of acetonitrile previously saturated with petroleum ether.
The acetonitrile was evaporated to dryness and the residue eluted from a Florisil
column [581]. In this technique, increasing proportions of ethyl ether to petroleum
ether were used to elute fractions containing increasingly polar insecticides. The extracts
were analysed by gas chromatography. Recoveries ofDDE, DDD and DDT were between
79 and 96 %. The detection limit for a 30 g oyster sample was 10 IJgkg-l.
Arias et al. [582] have described a method for the determination of organochlorine
insecticide residues in molluscs. The method involves extraction, Florisil column
cleanup, and analysis of the extract by thin-layer chromatography on silica gel G or
alumina with hexane or hexane-acetone (49: I) as solvent, or gas chromatography on a
polar column of 10 % of DC-200 on Chromosorb W HMDS and on a semipolar
column of5 % ofDC-200 plus 7.5 % ofQF-l on Chromosorb W, with electron capture
detection.
Ernst et al. [586,587] have determined, by gas chromatography-mass spectrometry,
residues of DDT, DDE, DDD, and polychlorinated biphenyls in scallops from the
English Channel. The procedure used for working up the tissue samples is summarized in Fig. 8.7.
Neudorf and Khan [590] investigated the uptake of 14C-labelled DDT, dieldrin, and
photodieldrin by Ankistrodesmus amalloides. The results of liquid scintillation spectrometric analyses show that the total pick-up of DDT during a 1-3 h period was 2-5
times higher than that of dieldrin, and 10 times higher than that of photodieldrin. The
algae metabolized 3-5 % of DDT to DDE, and 0.8 % to DDD. The metabolism of DDT
by Daphnia pulex was also monitored by exposing 100 organisms to 0.31 ppm of the
labelled pesticide for 24 h without feeding. The metabolites were then extracted and
203
de in marine organisms. These substances were separated and determined on a glass
column (4 m x 4 mm) packed with 3 % of SE-52 on Chromosorb W (AW DMCS) (80
to 100-mesh) and operated at 35°C, with argon (30 ml min-I) as carrier gas. An
electron capture detector was used, with argon-methane (9:1) as quench gas. A
limitation of this procedure is that compounds which boil considerably above 100°C
could not be determined.
8.2.4
Chlorinated Insecticides
Gas Chromatography. The determination of chlorinated insecticides in crustacea has
been discussed by several workers [581-589]. Mills et al. [581] dehydrated oyster
samples by mixing them with a 9: 1 mixture of anhydrous sodium sulphate and Quso
(a micro-fine silica). They could be held at room temperature for up to 15 days
without loss or degradation of chlorinated insecticides. The tissues of oysters were
homogenized. Approximately 30 g of the homogenate was added to a second Mason
jar and blended with a 9:1 mixture of sodium sulphate and Quso. By alternately
chilling and blending, a free-flowing powder was obtained. The blended sample was
wrapped in aluminium foil and shipped to the laboratory. Upon receipt of the sample,
it was weighed and extracted in a Soxhlet apparatus for 4 h with petroleum ether. The
extracts were then purified by concentrating and transferring the extract to separatory funnels. The extracts were diluted to 25 ml with petroleum ether and partitioned
with two 50 ml portions of acetonitrile previously saturated with petroleum ether.
The acetonitrile was evaporated to dryness and the residue eluted from a Florisil
column [581]. In this technique, increasing proportions of ethyl ether to petroleum
ether were used to elute fractions containing increasingly polar insecticides. The extracts
were analysed by gas chromatography. Recoveries ofDDE, DDD and DDT were between
79 and 96 %. The detection limit for a 30 g oyster sample was 10 IJgkg-l.
Arias et al. [582] have described a method for the determination of organochlorine
insecticide residues in molluscs. The method involves extraction, Florisil column
cleanup, and analysis of the extract by thin-layer chromatography on silica gel G or
alumina with hexane or hexane-acetone (49: I) as solvent, or gas chromatography on a
polar column of 10 % of DC-200 on Chromosorb W HMDS and on a semipolar
column of5 % ofDC-200 plus 7.5 % ofQF-l on Chromosorb W, with electron capture
detection.
Ernst et al. [586,587] have determined, by gas chromatography-mass spectrometry,
residues of DDT, DDE, DDD, and polychlorinated biphenyls in scallops from the
English Channel. The procedure used for working up the tissue samples is summarized in Fig. 8.7.
Neudorf and Khan [590] investigated the uptake of 14C-labelled DDT, dieldrin, and
photodieldrin by Ankistrodesmus amalloides. The results of liquid scintillation spectrometric analyses show that the total pick-up of DDT during a 1-3 h period was 2-5
times higher than that of dieldrin, and 10 times higher than that of photodieldrin. The
algae metabolized 3-5 % of DDT to DDE, and 0.8 % to DDD. The metabolism of DDT
by Daphnia pulex was also monitored by exposing 100 organisms to 0.31 ppm of the
labelled pesticide for 24 h without feeding. The metabolites were then extracted and