Non-Metals
155
p-dioxins (TCDD) tetrachlorodibenzo furans (TCDF) and octachloro-dibenzo-pdioxins (OCDD) is evident (Column (a) Table 7.13).
Compounds which do not interfere in this procedure include DDE, polychlorinated
biphenyls, methoxy polychlorinated biphenyls, polychlorinated diphenyl ethers, and
methoxy polychlorinated biphenyl ethers.
Determinations of 2,3,7,8 tetrachloro-dibenzo-p-dioxin in fish carried out by this
and other methods of analysis are compared in Table 7.14. The agreement, both in
identification and quantitation, between the results obtained by Smith et al. [463] and
those of the other laboratories was consistently good, and no false-positive results
were indicated in any of the determinations made with this procedure.
Lawrence et al. [464] detailed equipment and procedure for the determination of
dioxins in fish tissues and sediment samples involving isolation and extraction by acid
digestion, gel permeation chromatography, trisodium phosphate treatment, microalumina chromatography, and carbon-fibre column chromatography, followed by
determination of tetrachloro dibenzo-p-dioxins by gas chromatography-electron capture detection screening, and confirmation by high resolution gas chromatographymass spectrometry.
Clement et al. [465] compared results obtained by various techniques for the
determination of chlorinated dibenzo-p-dioxins and chlorinated dibenzofurans in
fish in a round robin experiment involving gas chromatography-mass spectrometry
also mass spectrometry-mass spectrometry and high resolution mass spectrometry.
They commented that analysis of these complex samples was difficult without extensive clean-up procedures. However, determination by gas chromatography and high
resolution mass spectrometry was possible with reduced clean-up compared with gas
chromatography and low resolution mass spectrometry.
Taguchi et al. [466] used high resolution mass spectrometry to determine polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans in fish. They used
mixtures of the solid aromatic hydrocarbons, coronene, tetraphenylcyclopentadiene,
and decacyclene as lockmasses in the analysis of polychlorinated dibenzo-p-dioxins
and polychlorinated dibenzofurans with between four and eight chlorine atoms.
Enhanced sensitivity, easier control of the lockmass concentration in the ion source,
and greater resolution between lockmass and sample ion signals were obtained for
this system compared to the conventional perfluorokerosene lockmass system. Both
systems exhibited a trend of decreasing signal strength with increasing chlorine
substitution and stronger signals obtained for polychlorinated dibenzo furans than
for polychlorinated-dibenzo-p-dioxins. Crummelt [467] has reviewed methods for the
determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo
furans in fish.
7.3.10
Hexachlorobenzene
Residues ofhexachlorobenzene in fish have been determined at the J.1g kg-l level using
gas chromatography combined with mass spectrometry [468].
155
p-dioxins (TCDD) tetrachlorodibenzo furans (TCDF) and octachloro-dibenzo-pdioxins (OCDD) is evident (Column (a) Table 7.13).
Compounds which do not interfere in this procedure include DDE, polychlorinated
biphenyls, methoxy polychlorinated biphenyls, polychlorinated diphenyl ethers, and
methoxy polychlorinated biphenyl ethers.
Determinations of 2,3,7,8 tetrachloro-dibenzo-p-dioxin in fish carried out by this
and other methods of analysis are compared in Table 7.14. The agreement, both in
identification and quantitation, between the results obtained by Smith et al. [463] and
those of the other laboratories was consistently good, and no false-positive results
were indicated in any of the determinations made with this procedure.
Lawrence et al. [464] detailed equipment and procedure for the determination of
dioxins in fish tissues and sediment samples involving isolation and extraction by acid
digestion, gel permeation chromatography, trisodium phosphate treatment, microalumina chromatography, and carbon-fibre column chromatography, followed by
determination of tetrachloro dibenzo-p-dioxins by gas chromatography-electron capture detection screening, and confirmation by high resolution gas chromatographymass spectrometry.
Clement et al. [465] compared results obtained by various techniques for the
determination of chlorinated dibenzo-p-dioxins and chlorinated dibenzofurans in
fish in a round robin experiment involving gas chromatography-mass spectrometry
also mass spectrometry-mass spectrometry and high resolution mass spectrometry.
They commented that analysis of these complex samples was difficult without extensive clean-up procedures. However, determination by gas chromatography and high
resolution mass spectrometry was possible with reduced clean-up compared with gas
chromatography and low resolution mass spectrometry.
Taguchi et al. [466] used high resolution mass spectrometry to determine polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans in fish. They used
mixtures of the solid aromatic hydrocarbons, coronene, tetraphenylcyclopentadiene,
and decacyclene as lockmasses in the analysis of polychlorinated dibenzo-p-dioxins
and polychlorinated dibenzofurans with between four and eight chlorine atoms.
Enhanced sensitivity, easier control of the lockmass concentration in the ion source,
and greater resolution between lockmass and sample ion signals were obtained for
this system compared to the conventional perfluorokerosene lockmass system. Both
systems exhibited a trend of decreasing signal strength with increasing chlorine
substitution and stronger signals obtained for polychlorinated dibenzo furans than
for polychlorinated-dibenzo-p-dioxins. Crummelt [467] has reviewed methods for the
determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo
furans in fish.
7.3.10
Hexachlorobenzene
Residues ofhexachlorobenzene in fish have been determined at the J.1g kg-l level using
gas chromatography combined with mass spectrometry [468].