58
River and Stream Sediments
including endrin, endrin aldehyde, p,p'-DDT, Mirex and decachlorobiphenyl. The
sample was extracted with carbon dioxide modified with 3 % methanol at 350 atmospheres and 50°C, and 85 % recovery of these compounds was archived.
2.4.72
Polychlorinated Biphenyls
Goerlitz and Law [128] determined chlorinated insecticides in sediment and bottom
material samples, which also contained PCBs, by extracting the sample with acetone
and hexane. The combined extracts were passed down an alumina column. The first
fraction (containing most of the insecticides and some polychlorinated biphenyls and
polychlorinated naphthalenes) was eluted with hexane and treated with mercury to
precipitate sulphur. If the polychlorinated hydrocarbons interfered with the subsequent gas chromatographic analysis, further purification on a silica gel column was
necessary.
Gas chromatography has been used extensively for the determination of chlorinated biphenyls in river sediments [129-133, 135-136]. Both capillary [129, 131, 132]
and packed [130] columns have been used. Kominar [130] used ultrasonic extraction
with 1:1 n-hexane-acetone to extract polychlorinated biphenyls from the sediment.
Bacterial dechlorination products of polychlorinated biphenyls have been identified
by gas chromatography [131]. Alford Stevens et al. [133] have reported on an interlaboratory study of the determination of polychlorinated biphenyls in environmental
sediments. Electron capture gas chromatography and mass spectrometry were used to
identify and determine polychlorinated biphenyls. For electron capture, an overall
standard deviation of 30 % was achieved whilst mass spectrometry gave 38 %.
McMurtreyet al. [135] investigated the feasibility of determining polychlorinated
biphenyls adsorbed on sediments by a procedure involving pyrolytic desorption at
1000 °c, followed by gas chromatography and mass spectrometry. The procedure was
capable of detecting polychlorinated biphenyl in sediment at the 10 mg kg- 1 level.
Robbat et al. [134] evaluated a thermal desorption, gas chromatographic-mass
spectrometric technique for the detection of polychlorobiphenyl in sediments and
soils.
Eganhouse and Gossett [750] studied the sources and magnitude of bias associated
with the determination of polychlorobiphenyls in environmental sediments.
Lagenfeld et al. [755] studied the effect of temperature and pressure on supercritical
fluid extraction efficiences of polychlorinated biphenyls in river sediments. At a
temperature of 50°C raising the pressure from 350 to 650 atmospheres had no
beneficial effect on recovery of polychlorinated biphenyls from sediments. Recovery
was improved, however, as the extraction temperature was increased from 50 °c to
200°C.
Lagenfeld et al. [755] compared supercritical monochlorodifluoromethane, nitrogen dioxide and carbon dioxide for the extraction of polychlorobiphenyle from
sediments. Monochlorodifluoro methane provided the highest recovery. Methanol
modified carbon dioxide provided a 90 % recovery of polychlorobiphenyls from sediments.
River and Stream Sediments
including endrin, endrin aldehyde, p,p'-DDT, Mirex and decachlorobiphenyl. The
sample was extracted with carbon dioxide modified with 3 % methanol at 350 atmospheres and 50°C, and 85 % recovery of these compounds was archived.
2.4.72
Polychlorinated Biphenyls
Goerlitz and Law [128] determined chlorinated insecticides in sediment and bottom
material samples, which also contained PCBs, by extracting the sample with acetone
and hexane. The combined extracts were passed down an alumina column. The first
fraction (containing most of the insecticides and some polychlorinated biphenyls and
polychlorinated naphthalenes) was eluted with hexane and treated with mercury to
precipitate sulphur. If the polychlorinated hydrocarbons interfered with the subsequent gas chromatographic analysis, further purification on a silica gel column was
necessary.
Gas chromatography has been used extensively for the determination of chlorinated biphenyls in river sediments [129-133, 135-136]. Both capillary [129, 131, 132]
and packed [130] columns have been used. Kominar [130] used ultrasonic extraction
with 1:1 n-hexane-acetone to extract polychlorinated biphenyls from the sediment.
Bacterial dechlorination products of polychlorinated biphenyls have been identified
by gas chromatography [131]. Alford Stevens et al. [133] have reported on an interlaboratory study of the determination of polychlorinated biphenyls in environmental
sediments. Electron capture gas chromatography and mass spectrometry were used to
identify and determine polychlorinated biphenyls. For electron capture, an overall
standard deviation of 30 % was achieved whilst mass spectrometry gave 38 %.
McMurtreyet al. [135] investigated the feasibility of determining polychlorinated
biphenyls adsorbed on sediments by a procedure involving pyrolytic desorption at
1000 °c, followed by gas chromatography and mass spectrometry. The procedure was
capable of detecting polychlorinated biphenyl in sediment at the 10 mg kg- 1 level.
Robbat et al. [134] evaluated a thermal desorption, gas chromatographic-mass
spectrometric technique for the detection of polychlorobiphenyl in sediments and
soils.
Eganhouse and Gossett [750] studied the sources and magnitude of bias associated
with the determination of polychlorobiphenyls in environmental sediments.
Lagenfeld et al. [755] studied the effect of temperature and pressure on supercritical
fluid extraction efficiences of polychlorinated biphenyls in river sediments. At a
temperature of 50°C raising the pressure from 350 to 650 atmospheres had no
beneficial effect on recovery of polychlorinated biphenyls from sediments. Recovery
was improved, however, as the extraction temperature was increased from 50 °c to
200°C.
Lagenfeld et al. [755] compared supercritical monochlorodifluoromethane, nitrogen dioxide and carbon dioxide for the extraction of polychlorobiphenyle from
sediments. Monochlorodifluoro methane provided the highest recovery. Methanol
modified carbon dioxide provided a 90 % recovery of polychlorobiphenyls from sediments.