Organic compounds in soils 43
by toluene extraction without pre-treatment. Alkaline pre-treatment increased the
extractability of higher-chlorinated CDDs (HiCDDs), whereas acid pre-treatment
slightly decreased their extractability. No change in extractability was observed for
higher–chlorinated CDFs under any conditions. The extractability of lower-chlorinated
CDD/Fs (LoCDD/Fs) and CoPCBs was increased only be acetone extraction. PCDD/F
homologue profiles in soil humic acid fractions and those in dead leaves, a major raw
material of soil humus, were also determined. These results suggested that the variations in the extractability of dioxin homologues are due mainly to variations in their
physical state in the soil, especially their interactions with soil humus.
Vasilic et al [269] measured the distribution of dibenzo-p-dioxins and dibenzofurans also polychlorobiphenyls in the vicinity of Croatian airports. The compounds
accumulated from air-dried soil samples by multiple ultrasonic extraction with an
n-hexane:acetone 1:1 mixture were analysed by capillary gas chromatography with
electron capture and ion-trap detection. Polychlorobiphenyls were quantified against
a standard Aroclor 1242/Aroclor 1260 mixture and a standard mixture and a standard
mixture of 17 individual polychlorobiphenyls congeners (IUPAC No.: 28, 52, 60, 74,
101, 105, 114, 118, 123, 138, 153, 156, 157, 167, 170, 180, and 189). The mass
fractions of total polychlorobiphenyls in 18 soils samples collected within the airport
premises ranged from 3 to 41327 µg/kg dry weight (median: 533 µg/kg dry weight),
and those in 21 samples collected at a distance ranging from several meters to 5 km
away from the airport fence, from less than 1 to 39 µg/kg dw (medium: 5 µg/kg dry
weight). The highest polychlorobiphenyls levels were determined in soils along the airport aprons where the aircrafts were serviced and refuelled. The polychlorobiphenyls
pattern was very similar to technical Aroclor 1260 in all airport soils. The polychlorobiphenyls pattern in 22 soils collected in the vicinity of electrical transformer stations
was dominated by congeners contained in Aroclor 1242. These soils contained 7 to
>400 µg/kg dry weight of total polychlorobiphenyls. One highly PCB-contaminated
airport soil sample was analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and
dibenzofurans (PCDs). With an international toxic equivalent (I-TEQ) of 9.7 ng/kg dry
weight, the airport soil contamination was within values typical for urban and rural
areas, and the congener patterns gave no clear indication for polychlorobiphenyls as
the only source of polychlorinated dibenzo-p-dioxins and polychlorodibenzofurans.
Gas chromatography-mass spectrometry
Gas chromatography-mass spectrometry has been used to determine 2,3,7,8tetrachloro-p-benzo dioxin in soil [270].
Tong et al [271] have described a high-resolution gas chromatographic-mass spectrometric method for the determination of monobromopolychlorodibenzo-p-dioxin in
soils and incinerator wastes.
A good example of the application of gas chromatography-mass spectrometry
to the determination of polychlorodibenzo-p-dioxin and dibenzofurans up to the
octochlorocongeners in soils and sediments is that of Smith et al [272] which, it is
claimed, is sufficiently sensitive to determine down to 1–5 parts per trillion of these
substances.
Di Domenico et al [273] have discussed analytical techniques used for the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in environmental samples taken after
by toluene extraction without pre-treatment. Alkaline pre-treatment increased the
extractability of higher-chlorinated CDDs (HiCDDs), whereas acid pre-treatment
slightly decreased their extractability. No change in extractability was observed for
higher–chlorinated CDFs under any conditions. The extractability of lower-chlorinated
CDD/Fs (LoCDD/Fs) and CoPCBs was increased only be acetone extraction. PCDD/F
homologue profiles in soil humic acid fractions and those in dead leaves, a major raw
material of soil humus, were also determined. These results suggested that the variations in the extractability of dioxin homologues are due mainly to variations in their
physical state in the soil, especially their interactions with soil humus.
Vasilic et al [269] measured the distribution of dibenzo-p-dioxins and dibenzofurans also polychlorobiphenyls in the vicinity of Croatian airports. The compounds
accumulated from air-dried soil samples by multiple ultrasonic extraction with an
n-hexane:acetone 1:1 mixture were analysed by capillary gas chromatography with
electron capture and ion-trap detection. Polychlorobiphenyls were quantified against
a standard Aroclor 1242/Aroclor 1260 mixture and a standard mixture and a standard
mixture of 17 individual polychlorobiphenyls congeners (IUPAC No.: 28, 52, 60, 74,
101, 105, 114, 118, 123, 138, 153, 156, 157, 167, 170, 180, and 189). The mass
fractions of total polychlorobiphenyls in 18 soils samples collected within the airport
premises ranged from 3 to 41327 µg/kg dry weight (median: 533 µg/kg dry weight),
and those in 21 samples collected at a distance ranging from several meters to 5 km
away from the airport fence, from less than 1 to 39 µg/kg dw (medium: 5 µg/kg dry
weight). The highest polychlorobiphenyls levels were determined in soils along the airport aprons where the aircrafts were serviced and refuelled. The polychlorobiphenyls
pattern was very similar to technical Aroclor 1260 in all airport soils. The polychlorobiphenyls pattern in 22 soils collected in the vicinity of electrical transformer stations
was dominated by congeners contained in Aroclor 1242. These soils contained 7 to
>400 µg/kg dry weight of total polychlorobiphenyls. One highly PCB-contaminated
airport soil sample was analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and
dibenzofurans (PCDs). With an international toxic equivalent (I-TEQ) of 9.7 ng/kg dry
weight, the airport soil contamination was within values typical for urban and rural
areas, and the congener patterns gave no clear indication for polychlorobiphenyls as
the only source of polychlorinated dibenzo-p-dioxins and polychlorodibenzofurans.
Gas chromatography-mass spectrometry
Gas chromatography-mass spectrometry has been used to determine 2,3,7,8tetrachloro-p-benzo dioxin in soil [270].
Tong et al [271] have described a high-resolution gas chromatographic-mass spectrometric method for the determination of monobromopolychlorodibenzo-p-dioxin in
soils and incinerator wastes.
A good example of the application of gas chromatography-mass spectrometry
to the determination of polychlorodibenzo-p-dioxin and dibenzofurans up to the
octochlorocongeners in soils and sediments is that of Smith et al [272] which, it is
claimed, is sufficiently sensitive to determine down to 1–5 parts per trillion of these
substances.
Di Domenico et al [273] have discussed analytical techniques used for the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in environmental samples taken after