Organics
75
with Echnicon type S resin (sulphate form) and maintained at 76°C. The sugars are
separated by pumping 89 % ethanol through the column and the eluate is mixed with
an alkaline solution of tetrazolium blue which is considerably more sensitive and less
corrosive than other dyes. The extinction is monitored at 520 nm.
3.4.4
Haloaromatic Hydrocarbons
Onuska and Terry [235] developed an integrated analytical procedure for determining
chlorinated benzene contaminants that enables quantitation of individual isomers as
low as O.4llg kg- I in sediment samples. Preparation of the sample can be performed
by using one of three techniques, namely, Soxhlet extraction, ultrasonic extraction or
steam distillation. Chlorinated benzenes are then characterized and quantified by
open tubular column gas chromatography with electron capture detection. Recoveries
of individual chlorinated benzene isomers at three different levels from two different
types of sediment, one low and one high in organic matter, were evaluated. Although
all three methods are quantitative, the steam distillation method was found to be the
most efficient for the determination as far as time and simplicity were concerned.
Data presented indicated that detection limits of this method are 0.4-10 I!g kg- I of
individual chlorobenzene isomers. Chlorobenzene recovery from bottom sediment
samples at concentration levels between 1 and 100 I!g kg- I was 86 ± 14 %.
The following chlorinated benzenes were determined in a sediment; 1,3dihexachlorobutadiene, 1,3, 5-trihexachlorobutadiene, 1,2, 4-trihexachlorobutadiene, 1,2, 3-trihexachlorobutadiene, 1,2,3,5- tetrahexachlorobutadiene, 1,2,4,5tetrahexachlorobutadiene and pentahexachlorobutadiene.
Lee et al. [236] demonstrated that the chlorobenzene and hexachloro-butadiene
contents of a lake sediment sample remained unchanged after four years storage in
the dark at 4°C. Sub samples were analysed periodically over the four years by Soxhlet
extraction, Florasil cleaning, and analysis by capillary column gas chromatography
with electron capture or mass spectrometric detection.
3.4.5
Polychlorinated Biphenyls
Eichelberger et al. [237] applied gas chromatography-mass spectrometry, with computer controlled repetitive data acquisition from selected specific ions, to the analyses
of PCBs in lake sediments. The polychlorinated biphenyl mixtures were separated by
gas chromatography at 180°C in a coiled glass column (6 ft x 0.78 in.) packed with
1.5 % OV-17 plus 1.95 % QF-l on Gas-Chrom Q (100 to 120-mesh), with helium
(30 ml min-I) as carrier gas. Effluent is passed via a glass jet enrichment device into a
quadrupole mass spectrometer controlled by a mini-computer in such a way that only
selected ions of specific m / e pass through the quadrupole field. There is a substantial
gain in sensitivity, without loss of qualitative information contained in the complete
mass system. This technique provides a basis for a sensitive qualitative and quantitative (from ion-abundance chromatograms obtained from subset scanning) analysis
for polychlorinated biphenyls.
75
with Echnicon type S resin (sulphate form) and maintained at 76°C. The sugars are
separated by pumping 89 % ethanol through the column and the eluate is mixed with
an alkaline solution of tetrazolium blue which is considerably more sensitive and less
corrosive than other dyes. The extinction is monitored at 520 nm.
3.4.4
Haloaromatic Hydrocarbons
Onuska and Terry [235] developed an integrated analytical procedure for determining
chlorinated benzene contaminants that enables quantitation of individual isomers as
low as O.4llg kg- I in sediment samples. Preparation of the sample can be performed
by using one of three techniques, namely, Soxhlet extraction, ultrasonic extraction or
steam distillation. Chlorinated benzenes are then characterized and quantified by
open tubular column gas chromatography with electron capture detection. Recoveries
of individual chlorinated benzene isomers at three different levels from two different
types of sediment, one low and one high in organic matter, were evaluated. Although
all three methods are quantitative, the steam distillation method was found to be the
most efficient for the determination as far as time and simplicity were concerned.
Data presented indicated that detection limits of this method are 0.4-10 I!g kg- I of
individual chlorobenzene isomers. Chlorobenzene recovery from bottom sediment
samples at concentration levels between 1 and 100 I!g kg- I was 86 ± 14 %.
The following chlorinated benzenes were determined in a sediment; 1,3dihexachlorobutadiene, 1,3, 5-trihexachlorobutadiene, 1,2, 4-trihexachlorobutadiene, 1,2, 3-trihexachlorobutadiene, 1,2,3,5- tetrahexachlorobutadiene, 1,2,4,5tetrahexachlorobutadiene and pentahexachlorobutadiene.
Lee et al. [236] demonstrated that the chlorobenzene and hexachloro-butadiene
contents of a lake sediment sample remained unchanged after four years storage in
the dark at 4°C. Sub samples were analysed periodically over the four years by Soxhlet
extraction, Florasil cleaning, and analysis by capillary column gas chromatography
with electron capture or mass spectrometric detection.
3.4.5
Polychlorinated Biphenyls
Eichelberger et al. [237] applied gas chromatography-mass spectrometry, with computer controlled repetitive data acquisition from selected specific ions, to the analyses
of PCBs in lake sediments. The polychlorinated biphenyl mixtures were separated by
gas chromatography at 180°C in a coiled glass column (6 ft x 0.78 in.) packed with
1.5 % OV-17 plus 1.95 % QF-l on Gas-Chrom Q (100 to 120-mesh), with helium
(30 ml min-I) as carrier gas. Effluent is passed via a glass jet enrichment device into a
quadrupole mass spectrometer controlled by a mini-computer in such a way that only
selected ions of specific m / e pass through the quadrupole field. There is a substantial
gain in sensitivity, without loss of qualitative information contained in the complete
mass system. This technique provides a basis for a sensitive qualitative and quantitative (from ion-abundance chromatograms obtained from subset scanning) analysis
for polychlorinated biphenyls.