82 Organic compounds in soils, sediments & sludges
extract of soil. Clean-up was by partitioning with methylene chloride, and final analysis was by high-performance liquid chromatography with UV detection at 260 nm.
Lagana et al [156] and Krynitsky et al [157] used the latter technique. In this method
the soil utilises a combined soil column extraction and off-line solid-phase extraction
for sample preparation. Analysis was by liquid chromatography-electrospray mass
spectrometry in selected ion monitoring mode. Several different extractants were evaluated for the purpose of soil column extraction optimisation. The system that best
optimises the extractability of imidazolines from the soil was found to be the mixture
of methanol-ammonium carbonate (0.1 M, 50:50 v/v). The total recovery of each imidazolines from soil at each of the two levels investigated ranted from 87% to 95%.
Under three selected ion monitoring conditions, the limit of detection (S/N = 3) was
found to be 0.1–0.05 ng/g in soil samples.
Examples of this type of herbicide are Imazapyr, m-imazamethabenz,
p-imazamethabenz, m, p-imazamethabenzmethyl, Imazethapyr and Imazaquin.
Imazapyr has been determined at the µg/kg level in 0.1 M ammonium acetate extracts
of soil by microwave-assisted extraction using electron capture negative chemical ionisation mass spectrometry [158]. High-performance liquid chromatography with UV
detection at 250 nm has been used to determine Imazapyr in methanol extracts of
soil [159].
3.7 ORGANOPHOSPHORUS INSECTICIDES
De Pasquale et al [160] used solid phase micro extraction to determine organophosphorus insecticides adsorption in water and soil matrices. These workers showed
that solid-phase micro extraction coupled with GC enables rapid and simple analysis of organophosphorus pesticides in a range of complex matrices. Investigations
were made into the extraction efficiencies from water of six organophosphorus insecticides (Methanmidophos, Omethoate, Dimethoate, Parathion methyl, Malathion and
Parathion ethyl) showing a wide range of polarities. Three solid phase micro- extraction fibres coated with different stationary phases, polydimethyl-siloxane, polyacrylate
and carbowax-divinylbenzene were investigated. Water was spiked with the pesticides
at concentrations from 1 to 0.01 µg mL
−1 , and the solutions used for optimization
of the procedure. The carbowax-divinylbenzene fibre, with a 65 µm coating, gave
the best performance. The optimised experimental conditions were sample volume
10 mL at 20
◦ C equilibration time 16 min, pH 5, and presence of 10% w/v NaCl. Solid
phase micro-extraction analyses were performed on solutions obtained by equilibrating aqueous pesticide solutions with six certified soils with various physic-chemical
characteristics. Solid phase micro-extraction data were also assessed by comparison
with analyses performed by using conventional solid-phase extraction. Results indicate
the suitability of solid phase micro-extraction.
Figure 3.6 shows a typical chromatogram calculated under the experimental conditions prescribed by De Pasquale et al [160] recovery were in the range 88 to 104%
from a variety of soils.
Rotich et al [161] studied the adsorption behaviour of organophosphorus insecticides in peat and soil samples and their degradation in aqueous solutions at different
temperatures and pH values.
extract of soil. Clean-up was by partitioning with methylene chloride, and final analysis was by high-performance liquid chromatography with UV detection at 260 nm.
Lagana et al [156] and Krynitsky et al [157] used the latter technique. In this method
the soil utilises a combined soil column extraction and off-line solid-phase extraction
for sample preparation. Analysis was by liquid chromatography-electrospray mass
spectrometry in selected ion monitoring mode. Several different extractants were evaluated for the purpose of soil column extraction optimisation. The system that best
optimises the extractability of imidazolines from the soil was found to be the mixture
of methanol-ammonium carbonate (0.1 M, 50:50 v/v). The total recovery of each imidazolines from soil at each of the two levels investigated ranted from 87% to 95%.
Under three selected ion monitoring conditions, the limit of detection (S/N = 3) was
found to be 0.1–0.05 ng/g in soil samples.
Examples of this type of herbicide are Imazapyr, m-imazamethabenz,
p-imazamethabenz, m, p-imazamethabenzmethyl, Imazethapyr and Imazaquin.
Imazapyr has been determined at the µg/kg level in 0.1 M ammonium acetate extracts
of soil by microwave-assisted extraction using electron capture negative chemical ionisation mass spectrometry [158]. High-performance liquid chromatography with UV
detection at 250 nm has been used to determine Imazapyr in methanol extracts of
soil [159].
3.7 ORGANOPHOSPHORUS INSECTICIDES
De Pasquale et al [160] used solid phase micro extraction to determine organophosphorus insecticides adsorption in water and soil matrices. These workers showed
that solid-phase micro extraction coupled with GC enables rapid and simple analysis of organophosphorus pesticides in a range of complex matrices. Investigations
were made into the extraction efficiencies from water of six organophosphorus insecticides (Methanmidophos, Omethoate, Dimethoate, Parathion methyl, Malathion and
Parathion ethyl) showing a wide range of polarities. Three solid phase micro- extraction fibres coated with different stationary phases, polydimethyl-siloxane, polyacrylate
and carbowax-divinylbenzene were investigated. Water was spiked with the pesticides
at concentrations from 1 to 0.01 µg mL
−1 , and the solutions used for optimization
of the procedure. The carbowax-divinylbenzene fibre, with a 65 µm coating, gave
the best performance. The optimised experimental conditions were sample volume
10 mL at 20
◦ C equilibration time 16 min, pH 5, and presence of 10% w/v NaCl. Solid
phase micro-extraction analyses were performed on solutions obtained by equilibrating aqueous pesticide solutions with six certified soils with various physic-chemical
characteristics. Solid phase micro-extraction data were also assessed by comparison
with analyses performed by using conventional solid-phase extraction. Results indicate
the suitability of solid phase micro-extraction.
Figure 3.6 shows a typical chromatogram calculated under the experimental conditions prescribed by De Pasquale et al [160] recovery were in the range 88 to 104%
from a variety of soils.
Rotich et al [161] studied the adsorption behaviour of organophosphorus insecticides in peat and soil samples and their degradation in aqueous solutions at different
temperatures and pH values.