56
River and Stream Sediments
2.4.9
Volatile Aliphatic Chloro Compounds
Charles and Simmons [111] obtained overall recoveries of 38 %, 48 % and 54 %
respectively, for chloroform, trichloroethylene and chlorobenzene from sediments
using purge and trap methods.
Murray and Riley [112,113] described gas chromatographic methods for the determination of trichloroethylene, tetrachloroethylene, chloroform, and carbon tetrachloride in sediments. These sediments were separated and determined on a glass column
(4 m x 4 mm) packed with 3 % of SE-52 on Chromosorb W (AW DMCS) (80-100mesh) and operated at 35 DC, with argon (30 ml min-I) as carrier gas. An electron
capture detector was used, with argon-methane (9:1) as quench gas. Chlorinated
hydrocarbons were stripped from water samples by passage of nitrogen and removed
from solid samples by heating in a stream of nitrogen. In each case, the compounds
were transferred from the nitrogen to the carrier gas by trapping on a copper column
(30 cm x 6 mm) packed with Chromosorb W (A W DMCS) (80-100-mesh) coated with
3 % of SE-52 and cooled at -78 DC, and subsequently sweeping on to the gas chromatographic column with the stream of argon. A limitation of this procedure was that
compounds which boil considerably above 100 DC could not be determined [114].
Amin and Narang [115] closed loop stripped volatile haloparaffins from sediments
and adsorbed the volatiles on Poropak N. The compounds were eluted with methanol
and the elute analysed for organic compounds by gas chromatography with electroncapture and photoionization detection. A detection limit of 7 Ilg kg- I for each photoionization active and 1 ng g-I for each electron capturing compound was achieved. Samples could be stored in methanol for up to 90 days without significant loss of the volatile
compounds. Recoveries ranged from 71 % (bromoform) to 111 % (fluorobenzene).
Gas chromatography-mass spectrometry has been applied to the determination of
volatiles in river sediment samples [116].
2.4.10
Non-Volatile Organochlorine Compounds
Hollies et al. [117] have carried out an extensive study of the determination of
chlorinated long chain (C 13 -C 30 ) normal paraffins (Cerechlors) in river sediments.
They considered liquid chromatography, gas chromatography and thin-layer chromatography. Chlorinated paraffins are separated from the sediment by Soxhlet extraction with petroleum ether. A concentrate of the extract is then cleaned up on an
alumina column which adsorbs these compounds, allowing impurities to pass
through. The chlorinated paraffins are then desorbed with toluene. Analysis of the
extract is carried out by thin-layer chromatography on silica. The plate is developed
by covering with a second plate coated with alumina and heating face to face at 240 DC.
The alumina plate is then sprayed with silver nitrate to visualize the separated
chloroparaffins as grey/black spots. Any chloroparaffins present in the extract are
then identified by reference to the 1\ values which are approximately 0.74 and 0.80 for
C 13 -C I7 and C 20 -C 30 chloro paraffins respectively. .
Other chlorinated hydrocarbons that have been determined in extracts of river
sediments by gas chromatography include higher chlorinated aromatic hydrocarbons,
River and Stream Sediments
2.4.9
Volatile Aliphatic Chloro Compounds
Charles and Simmons [111] obtained overall recoveries of 38 %, 48 % and 54 %
respectively, for chloroform, trichloroethylene and chlorobenzene from sediments
using purge and trap methods.
Murray and Riley [112,113] described gas chromatographic methods for the determination of trichloroethylene, tetrachloroethylene, chloroform, and carbon tetrachloride in sediments. These sediments were separated and determined on a glass column
(4 m x 4 mm) packed with 3 % of SE-52 on Chromosorb W (AW DMCS) (80-100mesh) and operated at 35 DC, with argon (30 ml min-I) as carrier gas. An electron
capture detector was used, with argon-methane (9:1) as quench gas. Chlorinated
hydrocarbons were stripped from water samples by passage of nitrogen and removed
from solid samples by heating in a stream of nitrogen. In each case, the compounds
were transferred from the nitrogen to the carrier gas by trapping on a copper column
(30 cm x 6 mm) packed with Chromosorb W (A W DMCS) (80-100-mesh) coated with
3 % of SE-52 and cooled at -78 DC, and subsequently sweeping on to the gas chromatographic column with the stream of argon. A limitation of this procedure was that
compounds which boil considerably above 100 DC could not be determined [114].
Amin and Narang [115] closed loop stripped volatile haloparaffins from sediments
and adsorbed the volatiles on Poropak N. The compounds were eluted with methanol
and the elute analysed for organic compounds by gas chromatography with electroncapture and photoionization detection. A detection limit of 7 Ilg kg- I for each photoionization active and 1 ng g-I for each electron capturing compound was achieved. Samples could be stored in methanol for up to 90 days without significant loss of the volatile
compounds. Recoveries ranged from 71 % (bromoform) to 111 % (fluorobenzene).
Gas chromatography-mass spectrometry has been applied to the determination of
volatiles in river sediment samples [116].
2.4.10
Non-Volatile Organochlorine Compounds
Hollies et al. [117] have carried out an extensive study of the determination of
chlorinated long chain (C 13 -C 30 ) normal paraffins (Cerechlors) in river sediments.
They considered liquid chromatography, gas chromatography and thin-layer chromatography. Chlorinated paraffins are separated from the sediment by Soxhlet extraction with petroleum ether. A concentrate of the extract is then cleaned up on an
alumina column which adsorbs these compounds, allowing impurities to pass
through. The chlorinated paraffins are then desorbed with toluene. Analysis of the
extract is carried out by thin-layer chromatography on silica. The plate is developed
by covering with a second plate coated with alumina and heating face to face at 240 DC.
The alumina plate is then sprayed with silver nitrate to visualize the separated
chloroparaffins as grey/black spots. Any chloroparaffins present in the extract are
then identified by reference to the 1\ values which are approximately 0.74 and 0.80 for
C 13 -C I7 and C 20 -C 30 chloro paraffins respectively. .
Other chlorinated hydrocarbons that have been determined in extracts of river
sediments by gas chromatography include higher chlorinated aromatic hydrocarbons,