Pesticide extraction

For pesticide extraction procedures pertaining to food samples, refer to U.S. government manuals on pesticide residue analysis. 

Chromatographic Conditions for Analysis of Carbamate Pesticides Extracted from Solution... 

Liu Z, Sirimanne SR, Patterson DG, Jr. 1994. Comprehensive two dimensional gas chromatography for the fast separation and determination of pesticides extracted from human serum. Anal Chem 66(19) 3086-3092. 

The results presented in Table VI for the 42 organochlorine pesticides extracted from spiked sand indicate that SFE with carbon dioxide worked reasonably well for 35 of the 42 compounds (recovery > 50 percent) from those 35 compounds, 30 compound had recoveries > 70 percent. Among the seven compounds with recoveries < 50 percent, two are very volatile (DBCP and hexachlorocyclopentadiene). Three of the remaining five compounds (chlorthalonil, captan, and endosulfan sulfate) gave very poor recoveries with carbon dioxide alone, probably because of their polarity however, in other experiments we have recovered them quantitatively from spiked sand with carbon dioxide modified with 10 percent methanol (1). Chlorobenzilate recoveries were poor, even when we used carbon dioxide with 10 percent methanol, and captafol was not tested with the carbon dioxide/methanol combination. 

Pesticides Extracted from Spiked Sand with Supercritical Carbon Dioxidea... 

Figure 6. Total ion current chromatogram of endogenous and spiked pesticides extracted from an EPA standard fish tissue.

Convenient and rapid detection of cholinesterase inhibition by pesticides extracted from sheep wool... 

Figure 15.13 Comprehensive two-dimensional GC chromatogram of a supercritical fluid extract of spiked human serum. Peak identification is as follows 1, dicamba 2, trifluralin 3, dichloran 4, phorate 5, pentachlorophenol 6, atrazine 7, fonofos 8, diazinon 9, chlorothalonil 10, terbufos 11, alachlor 12, matalaxyl 13, malathion 14, metalochlor 15, DCPA 16, captan 17, folpet 18, heptadecanoic acid. Adapted from Analytical Chemistry, 66, Z. Liu et al., Comprehensive two-dimensional gas chromatography for the fast separation and determination of pesticides extracted from human serum , pp. 3086-3092, copyright 1994, with permission from the American Chemical Society.

Senseman, S.A., Lavy, T.L., Matice, J.D., Gbur, E.E. (1995) Influenced of dissolved humic acid and Ca-montmorilloinite clay on pesticide extraction efficiency from water using solid-phase extraction disks. Environ. Sci. Technol. 29, 2647-2653. 

Until now, many substances including pesticides, extracts of plants, and microbial metabolites have been bioassayed to find inhibitory activity on AF production. Organophosphorus insecticides with cholinesterase inhibitory activity, such as dichlorvos (116 in Figure 26), can inhibit AF production by inhibiting the esterase... 

Previously, pesticide extraction procedures from grapes and wine in the multiresidue analysis were carried out with polar solvents such as methanol and acetone (Holland and Malcolm, 1992). To increase the recovery of more polar analytes, the extracts were salted out with NaCl, Na2S04 or MgS04, and then partitioned with non-polar solvents such as CH2C12, petroleum ether, etc (Holland and Malcolm, 1992). 

Pesticides are extracted from grapes with acetonitrile using a singlephase extraction followed by liquid-liquid partitioning formed by addition of MgS04 and NaCl. Removal of residual water and clean up are performed simultaneously by using dispersive solid-phase extraction. The pesticide extract was analyzed by GC/MS. 

In another. similar example [8] France et al. used a bed of activated alumina in the extraction vessel downstream of the sample itself to "scrub-out" (retain) the hpids while allowing hpophilic pesticides extracted from a grain sample to pass on to the collection/reconstitution device to produce a hpid-free fraction to pass on to a GC/ECD for analysis of the pesticides. This is particularly important since hpids must normaUy be removed from pesticide-containing extracts by long and tedious manual-column methods, evaporation and solvent exchange. 

TABLE 9.3. Percentage Recoveries of Pesticides Extracted by Solid-Phase Extraction With a C,s Cartridge from Red and White Wines Spiked at 0.10 (high) and O.Olmg/L (low) Levels2... 

Insecticide/ Soil History Parent Pesticide Extractable Metabolites Sol1-Bound 14C02... 

Recoveries (%) and Quantification Limits (LQ) of Organophosphorus Pesticides Extracted from Different Types of Water Sample Using SPE Cartridges with Different Sorbents... 

Some triazines, including atrazine and simazine, were extracted from water by SEE after preconcentration on sohd-phase extraction disks.The freeze-dried residue or SPE disk was then introduced into the extraction cell and eluted with either pure CO2 or methanol or acetone-modified CO2. SEE has been applied in combination with online sohd-phase extraction for pesticides, including triazines. However, this technique is still used mainly on solid matrixes. The main limitation with aqueous matrixes remains the miscibility of water with supercritical carbon dioxide. Recoveries of nonpolar pesticides, extracted by SEE technique using octacedyl-bonded silica, are generally effective with CO2 elution alone. This is not the case for semipolar and polar compounds, such as triazines and their degradation products. For example, the addition of... 

The effect of the ionic strength on pesticide extraction should be studied. This may produce more accurate and precise LLE procedures. 

There has been some concern over the method of pesticide extraction, particularly for harvester exposure residues. For applicators and mixer-loaders, methods can be developed as needed with defined... 

Amytal and rotenone inhibit electron Uansport at complex I. Rotenone is a natural pesticide extracted from the derris plant and so is popular with organic gardeners, with some justification as it is poorly absorbed from the gastrointestinal tract in humans and is therefore relatively harmless. However, it is rapidly absorbed through the gUls of fish and so is notoriously toxic to them. Chronic exposure to rotenone in humans reproduces Parkinson s disease. 

Microwave extraction is another possibility for obtaining pesticide extracts from soil samples (42). Compared with traditional procedures, this novel sample preparation method, consisting of microwave irradiation and centrifugation, is a time- and solvent-saving method (42). 

Kumaran, S. andMorita, M. (1995) Application of a cholinesterase biosensor to screen for organophosphorus pesticides extracted from soil. Talanta, 42 (4), 649-655. 

It is clear that with a combination of good seed harvesting and storage practices and hygiene, coupled with the processing advances discussed above, aflatoxin contamination of pesticidal extracts and ingredients need no longer be seen as a barrier to the full exploitation of neem. 

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