Non-Metals
149
regression analysis, for the determination of mirex by selected ion monitoring mass
spectrometric data and electron capture detection. The single-ion detection procedure is rapid and capable of screening and quantitating mirex levels as low as 500 fg. The
multiple ion detection technique extends the determination to include degradation
products of mirex. It does not suffer from previously reported interferences and can
be used for a wide range of samples.
7.3.9
Dioxins
Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and other substituted polychlorinated biphenyls, are three structurally and toxicologically related
families of anthropogenic chemicals that have, in recent years, been shown to have the
potential to cause serious environmental contamination. These substances are tracelevel components or byproducts in several large-volume and widely used synthetic
chemicals, principally polychlorinated biphenyls and chlorinated phenols, and can
also be produced during combustion processes and by photolysis. In general, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls are classified as highly toxic substances, although the toxicities are dramatically dependent on the number and positions of the chlorine
substituents. About 10 individual members of a total of 216 polychlorinated dibenzop-dioxins, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls
are among the most toxic man-made or natural substances to a variety of animal
species. The toxic hazards posed by these chemicals are exacerbated by their propensity to persist in the enviroment and to bioaccumulate readily, and although the rate of
metabolism and elimination is strongly species dependent, certain highly toxic isomers
have been observed to persist in the human body for more than 10 years. Work on the
determination of these classes of compounds in fish is discussed below.
Lamparski et al. [458] have developed a procedure for the determination of 10100 /lg kg- 1 quantities of 2,3,7,8 tetrachloro-dibenzo-p-dioxin in fish. The technique
involves digestion with alcoholic potassium hydroxide and extraction of the matrix
with hexane, followed by a series of absorbent and chemically-modified adsorbent
liquid column chromatographic clean-up steps involving the use of silica-sulphuric
acid, and alumina, and silica-silver nitrate. A final 'residue polishing' step via elevated
temperature reversed-phase high performance liquid chromatography is applied
prior to detection by multiple ion mode gas chromatography-mass spectrometry.
Using 13 C-Iabelled 2,3,7,8 tetrachlorodibenzo-p-dioxin as an internal standard and
carrier, the procedure has been validated for rainbow trout from approximately 10 to
100 ng kg-l 2,3,7,8 tetrachlorodibenzo-p-dioxin. Relative to this range, 2,3,7,8 tetrachloro dibenzo-p-dioxin recovery is 75 % ± 25 %, and the precision of a single
determination at the 95 % confidence level (2 0) is ± 20 % relative at 50 ng kg- 1 concentration.
Results obtained by this procedure in spiking experiments in which 10-100 ng kg- 1
quantities of 2,3,7,8 tetrachlorodibenzo-p-dioxin were added to trout gave recoveries
of between 80 and 120 %. Other anthropogenic compounds in the trout did not interfere.
149
regression analysis, for the determination of mirex by selected ion monitoring mass
spectrometric data and electron capture detection. The single-ion detection procedure is rapid and capable of screening and quantitating mirex levels as low as 500 fg. The
multiple ion detection technique extends the determination to include degradation
products of mirex. It does not suffer from previously reported interferences and can
be used for a wide range of samples.
7.3.9
Dioxins
Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and other substituted polychlorinated biphenyls, are three structurally and toxicologically related
families of anthropogenic chemicals that have, in recent years, been shown to have the
potential to cause serious environmental contamination. These substances are tracelevel components or byproducts in several large-volume and widely used synthetic
chemicals, principally polychlorinated biphenyls and chlorinated phenols, and can
also be produced during combustion processes and by photolysis. In general, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls are classified as highly toxic substances, although the toxicities are dramatically dependent on the number and positions of the chlorine
substituents. About 10 individual members of a total of 216 polychlorinated dibenzop-dioxins, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls
are among the most toxic man-made or natural substances to a variety of animal
species. The toxic hazards posed by these chemicals are exacerbated by their propensity to persist in the enviroment and to bioaccumulate readily, and although the rate of
metabolism and elimination is strongly species dependent, certain highly toxic isomers
have been observed to persist in the human body for more than 10 years. Work on the
determination of these classes of compounds in fish is discussed below.
Lamparski et al. [458] have developed a procedure for the determination of 10100 /lg kg- 1 quantities of 2,3,7,8 tetrachloro-dibenzo-p-dioxin in fish. The technique
involves digestion with alcoholic potassium hydroxide and extraction of the matrix
with hexane, followed by a series of absorbent and chemically-modified adsorbent
liquid column chromatographic clean-up steps involving the use of silica-sulphuric
acid, and alumina, and silica-silver nitrate. A final 'residue polishing' step via elevated
temperature reversed-phase high performance liquid chromatography is applied
prior to detection by multiple ion mode gas chromatography-mass spectrometry.
Using 13 C-Iabelled 2,3,7,8 tetrachlorodibenzo-p-dioxin as an internal standard and
carrier, the procedure has been validated for rainbow trout from approximately 10 to
100 ng kg-l 2,3,7,8 tetrachlorodibenzo-p-dioxin. Relative to this range, 2,3,7,8 tetrachloro dibenzo-p-dioxin recovery is 75 % ± 25 %, and the precision of a single
determination at the 95 % confidence level (2 0) is ± 20 % relative at 50 ng kg- 1 concentration.
Results obtained by this procedure in spiking experiments in which 10-100 ng kg- 1
quantities of 2,3,7,8 tetrachlorodibenzo-p-dioxin were added to trout gave recoveries
of between 80 and 120 %. Other anthropogenic compounds in the trout did not interfere.