30 Organic compounds in soils, sediments & sludges
Table 2.3 SIM Descriptors Used in GC/MS Analysis.
Desriptor*
Dwell Time, s
Benign Mass
End Mass
Set
Actual
187.5
88.5
0.050
0.052
265.5
266.5
0.120
0.105
271.5
272.5
0.120
0.105
*Total acquisition time 0.62 s; total scan time, 0.300; centroid sampling
intensity, 0.200 ms
Reprinted from L, Renberg et al, Analytical Chemistry 1996 68, 162, © 1996
American Chemical Society [146].
2.3.4 Polychlorobiphenyls
A wide variety of techniques have been employed to extract polychlorobiphenyls from
soil prior to analytical determination (Tables 2.4).
Hawthorne et al [150] compared supercritical extraction with chlorodifluoromethane, nitrous oxide and carbon dioxide for the extraction of polychlorobiphenyls
and polyaromatic hydrocarbons from soil. Chlorodifluoromethane provided the
highest recoveries while methanol modified carbon dioxide gave a 90% recovery of
polychlorobiphenyls from soil.
Lagenfeld et al [62] studied the effect of temperature and pressure on the supercritical fluid extraction of polychlorobiphenyls and polyaromatic hydrocarbons from
soil. At 50
◦ C raising the pressure from 356 to 650 atm had no effect on recovery of
polychlorobiphenyls. A temperature of 200
◦ C was necessary for effective extraction.
Von Bavel et al [152] used a solid phase carbon trap in conjunction with supercritical fluid chromatography for the simultaneous determination of polychlorobiphenyls,
pesticides, polychlorodibenzo-p-dioxins and polychlorodibenzofurans in soils.
Yang et al [153] used subcritical water to extract polychlorobiphenyls from soil
and sediments. Quantitative recovery of polychlorobiphenyls was observed at water
temperature of 250 and 300
◦ C. When the pressure was reduced to 50 atm at 300
◦ C
the extraction was complete within 5 minutes.
Supercritical fluid extraction with carbon dioxide has been applied to the
determination of polychlorobiphenyls in soil [154].
Gas chromatography
Thermal desorption gas chromatography, mass [188, 159, 173] and multidimensional
gas chromatography have been used [74, 176, 173].
Benicka et al [175] used multidimensional gas chromatography to separate the
atropisomers of polychlorobiphenyl congeners in extracts of soil. The correct enanatiomeric ratio was determined from the peak areas obtained by deconvolution of the
chromatograms.
Table 2.3 SIM Descriptors Used in GC/MS Analysis.
Desriptor*
Dwell Time, s
Benign Mass
End Mass
Set
Actual
187.5
88.5
0.050
0.052
265.5
266.5
0.120
0.105
271.5
272.5
0.120
0.105
*Total acquisition time 0.62 s; total scan time, 0.300; centroid sampling
intensity, 0.200 ms
Reprinted from L, Renberg et al, Analytical Chemistry 1996 68, 162, © 1996
American Chemical Society [146].
2.3.4 Polychlorobiphenyls
A wide variety of techniques have been employed to extract polychlorobiphenyls from
soil prior to analytical determination (Tables 2.4).
Hawthorne et al [150] compared supercritical extraction with chlorodifluoromethane, nitrous oxide and carbon dioxide for the extraction of polychlorobiphenyls
and polyaromatic hydrocarbons from soil. Chlorodifluoromethane provided the
highest recoveries while methanol modified carbon dioxide gave a 90% recovery of
polychlorobiphenyls from soil.
Lagenfeld et al [62] studied the effect of temperature and pressure on the supercritical fluid extraction of polychlorobiphenyls and polyaromatic hydrocarbons from
soil. At 50
◦ C raising the pressure from 356 to 650 atm had no effect on recovery of
polychlorobiphenyls. A temperature of 200
◦ C was necessary for effective extraction.
Von Bavel et al [152] used a solid phase carbon trap in conjunction with supercritical fluid chromatography for the simultaneous determination of polychlorobiphenyls,
pesticides, polychlorodibenzo-p-dioxins and polychlorodibenzofurans in soils.
Yang et al [153] used subcritical water to extract polychlorobiphenyls from soil
and sediments. Quantitative recovery of polychlorobiphenyls was observed at water
temperature of 250 and 300
◦ C. When the pressure was reduced to 50 atm at 300
◦ C
the extraction was complete within 5 minutes.
Supercritical fluid extraction with carbon dioxide has been applied to the
determination of polychlorobiphenyls in soil [154].
Gas chromatography
Thermal desorption gas chromatography, mass [188, 159, 173] and multidimensional
gas chromatography have been used [74, 176, 173].
Benicka et al [175] used multidimensional gas chromatography to separate the
atropisomers of polychlorobiphenyl congeners in extracts of soil. The correct enanatiomeric ratio was determined from the peak areas obtained by deconvolution of the
chromatograms.