Insecticides in soil

In marked contrast to hydrophobic compounds, more polar ones tend to be less adsorbed and to reach relatively high concentrations in soil water. Phenoxyalkanoic acids such as 2,4-D and MCPA are good examples (Figure 4.3). Their half-lives in soil are measured in weeks rather than years, and they are more mobile than OC insecticides in soils. When first applied they are lost only slowly. After a lag period of a... 

Fuhremann, T.W. and E.P. Lichtenstein. 1980. A comparative study of the persistence, movement, and metabolism of six carbon-14 insecticides in soils and plants. Jour. Agric. Food Chem. 28 446 452. 

Von Bavel et al. [55] have developed a solid phase carbon trap (PX-21 active carbon) for the simultaneous determination of polychlorodibenzo-p-dioxins and polychlorodibenzofurans also polychlorobiphenyls and chlorinated insecticides in soils using superfluid extraction liquid chromatography for the final determination. Supercritical fluid extraction with carbon dioxide has been applied to the determination of dioxins in soil [114],... 

Mangani et al. [13] have described a method for determining extract chlorinated insecticides in soil. In this procedure a short column is packed with the soil sample. The insecticides in the soil are desorbed by a suitable solvent mixture chosen for its polarity characteristics. 

Supercritical fluid extraction with carbon dioxide has been applied to the determination of chlorinated insecticides in soil [259],... 

Novikova [21] has reviewed the literature (209 references) covering the extraction, clean-up and analysis of organochlorine (and organophosphorus) insecticides in soil. Johnson and Starr [22] and Chiba and Morley [4] have studied factors affecting the extraction of Dieldrin and Aldrin from different soil types ultrasonic extraction was recommended by these workers. Lopez-Avila et al. [23] used microwave assisted extraction to extract chlorinated insecticides from soils. 

Mangani et al. [13] used Carbopack B columns to recover chlorinated insecticides in soil samples. These workers noted that, although the principles governing the adsorption and extraction process in the extraction in soil analysis are the same as those that govern liquid-solid chromatography, the main feature of a chromatographic column, i.e. separation efficiency, is almost completely absent. 

The procedure described by Suzuki et al. [11, 12], discussed in section 9.1.1.1 for the determination of chlorinated insecticides in soils has also been applied to hexane extracts of river sediments using high-resolution gas chromatography with glass capillary columns. Minimum detectable levels of a-BHC, fs-BHC, -BHC, P-BHC, Heptachlor, Heptachlor epoxide, Aldrin, Dieldrin, Endrin, p,p -DDE, p,p -TDE and p,p -DDT in lOOg samples of bottom sediment were 0.0005, 0.0032, 0.0014, 0.0040, 0.0012, 0.0020, 0.0014, 0.0020, 0.0056, 0.0032, 0.0080 and 0.0120mg kgr1 respectively. 

The supercritical fluid chromatographic procedure [20] described in section 9.1.1.5 for the determination of organochlorine insecticides in soils has also been applied to river sediments. Snyder et al. [20] compared supercritical fluid extraction with classical sonication and Soxhlet extraction for selected organochlorine insecticides. Samples of sediments extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave =85% recovery of organochlorine insecticides including Dichlorvos, Diazinon, Endrin, Endrin aldehyde, decachlorobiphenyl, p,p -DDT and Mirex. 

Snyder et al. [94] compared supercritical extraction with classical sonication and Soxhlet extraction for the extraction of selected organophosphorus insecticides from soil. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of Diazinon (diethyl-2-isopropyl-6-methyl-4-pyrimidinyl phosphorothiodate or 0,0 diethyl-0-(2-isopropyl-6-methyl-4-pyrimidyl) phosphorothioate). Ronnel (or Fenchlorphos) 0,0-dimethyl-0-2,4,5 trichlorophenol phosphorothiodate), Parathion ethyl (diethyl-p-nitrophenyl (phosphorothioate), Tetrachlorovinphos (trans,-2-chloro-l-(2,4,5 trichlorophenyl) vinyl (chlorophenyl-O-methylphenyl phosphorothioate) and Methiadathion. Supercritical fluid extraction with methanol modified carbon dioxide has been applied to the determination of organophosphorus insecticides in soil [260]. 

Novikova [21] has reviewed the literature (209 references) covering the extraction, clean-up and analysis of organophosphorus insecticides in soil (also food). 

Snyder et al. [23] compared supercritical fluid extraction with classical sonication and Soxhlet extraction from the analysis of selected insecticides in soils. 

The microwave assisted extraction for organic compounds including polyaromatic hydrocarbons, phenols and organochlorine insecticides, described in section 11.1.8 [25] has been applied to sediments. The application of supercritical fluid extraction to the determination of various insecticides in soils described in section 11.1.7 [23] has been applied to river sediments. 

Nash RG, Woolson EA. 1967. Persistence of chlorinated hydrocarbon insecticides in soils. Science 157 924-927. 

Sharom MS, Miles JR, Harris CR, et al. 1980a. Behavior of 12 insecticides in soil and aqueous suspensions of soil and sediment. Water Res 14 1095-1100. 

Racke, K.D. and Coats, J.R. Enhanced degradation and the comparative fate of carbamate insecticides in soil. J. Agric. Food Chem., 36(5) 1067-1072, 1988. 

Pyle and Marcus [ 102] achieved low ppb detection limits for the determination of organochlorine insecticides in soil using accelerated solvent extraction followed by gas chromatography ion trap tandem mass spectrometry. Richter et al. [103] showed that accelerated solvent extraction gave essentially equivalent recoveries of chlorinated dibenzo-p-dioxins and dibenzofurans from soil compounds to Soxhlet extraction, but in less time and using much less solvent. 

The first step in the determination of insecticides in soil is to efficiently extract the insecticide from the soil. The insecticide content of the extract can then be determined by methods based, usually, on gas chromatography, preferably linked to a mass spectrometric detector. 

Table 4.3. Gas chromatographic methods for determination of chlorinated insecticides in soil extracts (from author s own files)...

Hartonen et al. [286] have reported various extraction techniques for organochlorine insecticides in soils. Trapping efficiencies were reported for organochlorine insecticides, selected polychlorinated benzenes, polybromi-nated biphenyls, and polybrominated diphenyl ethers. 

Generally, a nitrogen phosphorus-specific detector is used in the determination of organophosphorus insecticides in soil [316-318]. Use of an acetone-n-hexane extraction solvent led to recoveries of 54-83%. 

Abbot combined gas chromatography with mass spectrometry [317]. Skladal et al. [319] used amperometric biosensors based on acetyl or bu-tyrylcholinesterase for the kinetic determination of organophosphorus insecticides in soil extracts. 

Gas chromatography and high-performance liquid chromatography with NP detection [326-328], photoionisation detection and mass spectrometric detection [329-332] have all been used in general surveys of pesticides in insecticides in soils. 

Bowman, B. T., and Sans, W. W. (1985). Partitioning behavior of insecticides in soil-water systems. II. Desorption hysteresis effects. /. Environ. Qual. 14, 270-273. 

Chemical Name S -(ferf-butylthio)methyl O, O-diethyl phosphorodithioate />-[[( 1,1-dimethylethyl)Lhio] methyl 0,0-diethyl phosphorodithioate phosphorodithioic acid S-((/er/-butylthio)methyl) 0,0-diethyl ester Uses insecticide in soil to control insects and also used as nematocide to control nematodes in beet, maize, cotton, sorghum, onions, cabbage, and bananas. 

Felsot, A.S., Enhanced biodegradation of insecticides in soil Implications for agroecosystems, Annu. Rev. Entomol., 34,453,1989. 

Karmakar, R., Singh, S.B., and Kulshrestha, G., Persistence and transformation of thiamethoxam, a neonicotinoid insecticide, in soil of different agroclimatic zones of India, Bull. Environ. Contam. Toxicol, 76,400, 2006. 

Figure 3 shows separation of some organophosphorus insecticides by thin-layer chromatography, and Figure 4 shows a chromatogram of some organochlorine insecticides in soil extracts. 

CHAPMAN HARRIS Insecticides in Soil Microbial Activity... 

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