Organics
59
2.4.13
Trialkyl and Triaryl Phosphates
Ishikawa et al. [137] developed procedures to determine the trialkyl and triaryl
phosphate esters in sediment, involving extraction with dichloromethane (for water)
or acetone (for sediment), followed by gas chromatography using a flame photometric detector and gas chromatography-mass spectrometry after clean-up through a
Florisil column.
2.4.14
Organophosphorus Insecticides
A gas chromatographic procedure using electron capture detection has been described for the determination of dursban (O,O-diethyl-O- (3, 5, 6-trichloro-2-pyridyl
phosphorothioate) in water and silt (Rice and Dishberger [139]). In this method,
water samples are extracted with dichloromethane, the extract is evaporated, and a
solution of the residue is cleaned up on a column of silicic acid, dursban being eluted
with hexane. The eluate is evaporated to dryness under reduced pressure, and a
solution of the residue in hexane is subjected to gas chromatography. Down to
0.11lS kg- I of dursban in sediment could be determined; average recoveries from
sediment was 83 %.
Deutsch et al. [140] determined dursban in sediments by an extraction gas chromatographic procedure which was capable of determining down to 0.01 mg kg- I dursban
using a 10 g sample.
To determine traces of organophosphorus insecticides and related compounds in
sediment, Kjolholt [141] homogenized the samples and subjected them to Soxhlet
extraction with acetone-N-hexane. The extract was partitioned between methylene
chloride and water and subjected to adsorption chromatography and analysed using
gas chromatography and nitrogen-phosphorus detection. The influences of freezedrying and of pH on extraction efficiency were studied. Interference by elemental
sulphur was examined. Recoveries at the Ilg- 1 kg level were 54.6-82.4 %. Detection
limits were 95-220 Ilg kg-I.
The supercritical carbon dioxide extraction procedure [133] described in sect.
2.4.11 has also been applied with 2:: 85 % recovery to the recovery of organophosphorus insectides from sediments. Compounds studied included Parathron ethyl, methidathion and tetrachlorovinphos.
Grob et al. [756] compared supercritical extraction with classic sonication and
Soxhlet extraction from river sediments for selected organophosphorus insecticides
including diazinon, Ronnel, parathion ethyl, methidathion and tetrachlorovinphos.
Samples extracted with supercritical carbon dioxide modified with 3 % methyl alcohol
at 350 DC atmospheres and 50 DC gave a recovery of at least 85 %.
2.4.15
Herbicides
Spengler and Jumar [144] used a spectrophotometric method and thin layer chromatography to determine carbamate and urea herbicide residues in sediments. The
59
2.4.13
Trialkyl and Triaryl Phosphates
Ishikawa et al. [137] developed procedures to determine the trialkyl and triaryl
phosphate esters in sediment, involving extraction with dichloromethane (for water)
or acetone (for sediment), followed by gas chromatography using a flame photometric detector and gas chromatography-mass spectrometry after clean-up through a
Florisil column.
2.4.14
Organophosphorus Insecticides
A gas chromatographic procedure using electron capture detection has been described for the determination of dursban (O,O-diethyl-O- (3, 5, 6-trichloro-2-pyridyl
phosphorothioate) in water and silt (Rice and Dishberger [139]). In this method,
water samples are extracted with dichloromethane, the extract is evaporated, and a
solution of the residue is cleaned up on a column of silicic acid, dursban being eluted
with hexane. The eluate is evaporated to dryness under reduced pressure, and a
solution of the residue in hexane is subjected to gas chromatography. Down to
0.11lS kg- I of dursban in sediment could be determined; average recoveries from
sediment was 83 %.
Deutsch et al. [140] determined dursban in sediments by an extraction gas chromatographic procedure which was capable of determining down to 0.01 mg kg- I dursban
using a 10 g sample.
To determine traces of organophosphorus insecticides and related compounds in
sediment, Kjolholt [141] homogenized the samples and subjected them to Soxhlet
extraction with acetone-N-hexane. The extract was partitioned between methylene
chloride and water and subjected to adsorption chromatography and analysed using
gas chromatography and nitrogen-phosphorus detection. The influences of freezedrying and of pH on extraction efficiency were studied. Interference by elemental
sulphur was examined. Recoveries at the Ilg- 1 kg level were 54.6-82.4 %. Detection
limits were 95-220 Ilg kg-I.
The supercritical carbon dioxide extraction procedure [133] described in sect.
2.4.11 has also been applied with 2:: 85 % recovery to the recovery of organophosphorus insectides from sediments. Compounds studied included Parathron ethyl, methidathion and tetrachlorovinphos.
Grob et al. [756] compared supercritical extraction with classic sonication and
Soxhlet extraction from river sediments for selected organophosphorus insecticides
including diazinon, Ronnel, parathion ethyl, methidathion and tetrachlorovinphos.
Samples extracted with supercritical carbon dioxide modified with 3 % methyl alcohol
at 350 DC atmospheres and 50 DC gave a recovery of at least 85 %.
2.4.15
Herbicides
Spengler and Jumar [144] used a spectrophotometric method and thin layer chromatography to determine carbamate and urea herbicide residues in sediments. The