Insecticides and herbicides in soils 73
Table 3.5 High-performance liquid chromatographic methods for the determination of Atrazine
herbicides in soil extracts.
Atrazine herbicide
Extraction method
Comments
Reference
Cyanazine
–
Microbore column with
54
Array detection and
Multichannel integrator.
Limit of detection: 0.25 ng absolute
Atrazine and
Cyclohexyl solidHigh-performance liquid
55–57
metabolites
phase extraction
chromatography with photodiode
Cartridge use to
array detection
Separate Atrazine from
soil extract
Triazine
Methanol, C 18 solidGradient, C 18 high performance
58
herbicides
phase extraction
liquid chromatography with UV
Detection at 220 nm. Limit of
Detection: ppb
Terbutylazine and
Hot acetone then
High-performance liquid
59–60
its degradation
adsorption on cation
chromatography with photodiode
products
exchange solid-phase
array detection
cartridge
Atrazine and its
Microwave assisted and
Liquid chromatography with
71
conversion products
solid-phase extraction
UV detection
Source: Author’s own files.
3.3 PHENOXY ACETIC ACID HERBICIDES
Phenoxyalkanoic acid herbicides are not amenable to direct gas chromatographic determination because of the high polarity or low volatility of the compounds and must
be converted to their more volatile derivatives. The sensitivity of the electron capture
detector towards alkyl esters of 4-chloro-2-methylphenoxy acetic acid, 4-chloro-2methylphenoxy butyric acid, etc., is very poor. The methyl ester of 4-chloro-2-methyl
phenoxy acetic acid was 100 times less sensitive to electron affinity detection than
2,4-D methyl ester [74].
Yip et al [75] reported that the binding of the soil particles and organic matter with the herbicide residues prevented the complete extraction of them with an
organic solvent. Upchurch and Mason et al [76] found that the extent of adsorption of the herbicides is highly dependent on the type of organic matter and of
clay as well as on the amounts of their constituents in soil. Sattar and Passivirta
et al [78] support the view that organic matter is the main factor which influences
the fate of herbicides and their analyses in the soil. The sandy and clay loan soils
had high organic matter content but sandy loam and clay soils very low organic
matter contents. Consequently, significantly higher recoveries of the residues were
generally obtained from the latter soil materials than from sandy loan and clay.
In addition, the sandy and clay loam soils gave selectively lower 5-chloro-3-methyl
catechol recoveries related to recoveries of 4-chloro-2methyl phenoxy acetic acid and
4-chloro-o-cresol.
Table 3.5 High-performance liquid chromatographic methods for the determination of Atrazine
herbicides in soil extracts.
Atrazine herbicide
Extraction method
Comments
Reference
Cyanazine
–
Microbore column with
54
Array detection and
Multichannel integrator.
Limit of detection: 0.25 ng absolute
Atrazine and
Cyclohexyl solidHigh-performance liquid
55–57
metabolites
phase extraction
chromatography with photodiode
Cartridge use to
array detection
Separate Atrazine from
soil extract
Triazine
Methanol, C 18 solidGradient, C 18 high performance
58
herbicides
phase extraction
liquid chromatography with UV
Detection at 220 nm. Limit of
Detection: ppb
Terbutylazine and
Hot acetone then
High-performance liquid
59–60
its degradation
adsorption on cation
chromatography with photodiode
products
exchange solid-phase
array detection
cartridge
Atrazine and its
Microwave assisted and
Liquid chromatography with
71
conversion products
solid-phase extraction
UV detection
Source: Author’s own files.
3.3 PHENOXY ACETIC ACID HERBICIDES
Phenoxyalkanoic acid herbicides are not amenable to direct gas chromatographic determination because of the high polarity or low volatility of the compounds and must
be converted to their more volatile derivatives. The sensitivity of the electron capture
detector towards alkyl esters of 4-chloro-2-methylphenoxy acetic acid, 4-chloro-2methylphenoxy butyric acid, etc., is very poor. The methyl ester of 4-chloro-2-methyl
phenoxy acetic acid was 100 times less sensitive to electron affinity detection than
2,4-D methyl ester [74].
Yip et al [75] reported that the binding of the soil particles and organic matter with the herbicide residues prevented the complete extraction of them with an
organic solvent. Upchurch and Mason et al [76] found that the extent of adsorption of the herbicides is highly dependent on the type of organic matter and of
clay as well as on the amounts of their constituents in soil. Sattar and Passivirta
et al [78] support the view that organic matter is the main factor which influences
the fate of herbicides and their analyses in the soil. The sandy and clay loan soils
had high organic matter content but sandy loam and clay soils very low organic
matter contents. Consequently, significantly higher recoveries of the residues were
generally obtained from the latter soil materials than from sandy loan and clay.
In addition, the sandy and clay loam soils gave selectively lower 5-chloro-3-methyl
catechol recoveries related to recoveries of 4-chloro-2methyl phenoxy acetic acid and
4-chloro-o-cresol.