In vitro release of bound (nonextractable) atrazine residues from corn plants by chicken liver homogenate and bovine rumen liquor

Su, Khan; Mh, Akhtar

doi:10.1021/jf00117a041

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…The gas chromatograph used was a Varían Model 3700 equipped with a 63Ni and an AFID detector. The GC conditions were similar to those described earlier for various pesticide-treated soil and crop samples Khan etal., 1976;Lichtenstein et al, ,1977; Zhang et al, 1984; Khan and Akhtar, 1983; Khan et al, 1984). The identity of the compounds was confirmed by comparing the GC retention times with those of authentic samples, by cochromatography, and finally by GC-MS. A high-resolution mass spectrometer, Model VG 2AB-2F, connected to a Varían GC Model 3700 was used.…”

Section: Methodsmentioning

confidence: 90%

“…Chromatography and Analysis. The supercritical methanol extracts and the HTD distillates were subjected to column chromatography for cleanup as descried earlier for prometryn (Khan and Hamilton, 1980), atrazine (Khan and Akhtar, 1983), deltamethrin (Zhang et al, 1984), dieldrin (Khan et al, 1984), carbofuran (Khan et al, 1984), and diuron, 2,4-D, and methylparathion (Sherma and Beroza, 1979). Extracts of samples, treated with prometryn, atrazine, deltamethrin, carbofuran, and 2,4-D were also derivatized prior to GC.…”

Section: Methodsmentioning

confidence: 99%

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Supercritical methanol: an efficacious technique for the extraction of bound pesticide residues from soil and plant samples

Capriel¹,

Haisch²,

Khan³

1986

J. Agric. Food Chem.

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Section: Methodsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Supercritical methanol: an efficacious technique for the extraction of bound pesticide residues from soil and plant samples

Capriel¹,

Haisch²,

Khan³

1986

J. Agric. Food Chem.

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“…A number of chemical linkage types of soluble as well as bound conjugates have now been recognized to be labile under simulated stomach conditions and can therefore be predicted to be bioavailable (Table 3). Digestive enzyme mixtures have also been applied for this purpose 10, 17, 58. Such model experiments may allow a preliminary estimate of bioavailability without sacrificing animals.…”

Section: Model Experiments For Formation and Bioavailabilitymentioning

confidence: 99%

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Sandermann

2004

Pest Management Science

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Plants are well known to incorporate pesticides into bound and unextractable residues that resist solubilization in common laboratory solvents and are therefore not accessible to standard residue analysis. A characterization of such residues has been proposed for incorporation rates above trigger values of 0.05 mg kg(-1) parent pesticide equivalents, or percentage values of 10% (United States Environmental Protection Agency, 1995) or 25% (Commission of the European Communities, 1997) of the total radioactive residue. These trigger values are often exceeded. The present review describes the current status of the chemical characterization and animal bioavailability of bound and unextractable residues that may be xenobiotic in nature or result from natural recycling of simple degradation products. The latter case represents a mechanism of detoxification. Bound residues have been shown to be covalent or non-covalent in nature. With regard to the plant matrix molecules involved, incorporation into proteins, lignins, pectins, hemicelluloses and cutins has been demonstrated, and four covalent linkage types are known. Animal feeding experiments have revealed cases of low as well as high bioavailability. Many of the studies are limited by experimental uncertainties and by results only being reported as relative percentage values rather than absolute exposure. A preliminary value of absolute exposure from bound and unextractable residues is derived here for the first time from eight case studies. The mean exposure (ca 1.5 mg kg(-1) pesticidal equivalents) exceeds some of the existing maximum residue levels (MRLs) of residual free pesticides that are typically in the range of 0.05-1 mg kg(-1). A mathematical framework for the correction of current maximum residue levels is presented for cases of highly bioavailable bound residues. As bound pesticidal residues in food plants could represent a source of significant consumer exposure, an experimental test scheme is proposed here. It consists of basic chemical characterization, model digestibility tests and, in exceptional cases, animal bioavailability and additional toxicological studies.

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“…In a recent study, bovine runen liquor had no effect on plant non-extractable residues from atrazine (ref. 61). From these studies it can be concluded that covalently bound non-extractable residues in plants are not in the main bioavailable to animals.…”

Section: Fate Of Plant Non-extractable Residues In Animalsmentioning

confidence: 96%

Non-extractable pesticide residues in soils and plants

Roberts¹

1984

Pure and Applied Chemistry

142

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In vitro release of bound (nonextractable) atrazine residues from corn plants by chicken liver homogenate and bovine rumen liquor

Cited by 6 publications

References 9 publications

Supercritical methanol: an efficacious technique for the extraction of bound pesticide residues from soil and plant samples

Supercritical methanol: an efficacious technique for the extraction of bound pesticide residues from soil and plant samples

Bound and unextractable pesticidal plant residues: chemical characterization and consumer exposure

Non-extractable pesticide residues in soils and plants

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