Herbicide metabolites

Extraction and cleanup of diphenyl ether herbicide metabolites in plants... 

Barcelo D, Chiron S, Fernandez Alba A, Valverde A, Alpendurada MF (1996) Monitoring pesticides and metabolites in surface water and groundwater in Spain. Herbicide Metabolites in Surface Water and Groundwater, vol 630, pp 237-253... 

Mills and Thurmen [105] used a mixed method for the isolation of triazine herbicide metabolites from aquifer sediments using automated solid phases extraction with a mixture of methanol and water (4 1 V/V). Following evaporation of the methanol phases, the metabolites were collected in a column of Cl8 octadecyl resin. The analytes were then stripped from the column with ethyl acetate leaving impurities on the column. Down to O.lpg kg-1 triazine could be determined. 

Lawruk, T., C. Hottenstein, J. Fleeker, F. Rubio, and D. Herzog (1996). Factors influencing the specificity and sensitivity of triazine immunoassays. In Herbicide Metabolites in Surface Water and Groundwater. ACS Symposium Series 630. Washington, DC American Chemical Society, pp. 43-52. 

McLaughlin, R.A. and B.S. Johnson (1997). Optimizing recoveries of two chlorotriazine herbicide metabolites and 11 pesticides from aqueous samples using sohd-phase extraction and gas chromatography-mass spectrometry. J. Chromatogr. A, 790 161-167. 

Ferrer, I., E.M. Thurman, and D. Barcelo (1997). Identification of ionic chloroacetanilide-herbicide metabolites in surface water and groundwater by HPLC/MS using negative ion spray. Anal. Chem., 69 4547-4553. 

Scribner, E.A., D.A. Goolsby, E.M. Thurman, M.T. Meyer, and W.A. Battaglin (1996). Concentrations of selected herbicides, herbicide metabolites, and nutrients in outflow from selected midwestem reservoirs April 1992 - September 1993 USGS Open-File Report 96-393. 

Scribner, E.A., E.M. Thurman, and L.R. Zimmerman (2000b). Analysis of selected herbicide metabolites in surface and groundwater of the US Sci. Total Environ., 248 157-168. 

In the late 1970s HPLC provided an ideal tool for the analysis of pollutants and other environmental contaminants. Techniques were developed for analyzing chlorophenols, pesticide residues, and metabolites in drinking water and soil (parts per trillion) and trace organics in river water and marine sediments, and for monitoring industrial waste water and polynuclear aromatics in air. Techniques were also developed for determining fungicides and their decomposition products and herbicide metabolites in plants and animals. 

Widmer S. K. and Spalding R. F. (1996) Assessment of herbicide transport and persistence in groundwater a review. In Herbicide Metabolites in Surface Water and Ground-water, ACS Symp. Ser. (eds. M. T. Meyer and... 

These compounds are examples of nonionic, polar herbicide metabolites (Fig. 7.15). The examples shown below are degradation products of the triazine compounds shown in Section 7.10.4. They are nonionic compounds that are formed in soil by the dealkylation of the parent compounds. They are considerably more soluble than the parent compounds with aqueous solubilities equal to or greater than 1000 mg/L. Therefore, the sorbent to choose in this case is the styrene-divinylbenzene or graphitized carbon. The compounds are soluble in ethyl acetate or methanol, either of which may be used as an elution solvent. The C-18 sorbent may also be used with good recovery of either deethylatrazine or deisopropylatrazine, but with no recovery of the didealky-latrazine. 

From the available literature, it can be underlined that the toxicity of major herbicide metabolites is not yet well known and analytical standards are not always available. The reduced molecular weight and high polarity of metabolites make them more difficult to analyze, and their removal from drinking water plants is not easy to achieve. However, some of them can be analyzed in the frame of normalized methods, in particular those compounds with physico chemical properties very similar to these of their parent compounds. 

The main investigated herbicide metabolites are presented in Table 26.2. 

Lerch, R. N., Donald, W. W., Li, Y.-X., and Alberts, E. E., Hydroxylated atrazine degradation products in a small Missouri stream, Ch 19, In Herbicide Metabolites in Surface Water and Groundwater, Meyer, M. T. and Thurmann, E. M. Eds., American Chemical Society Symposium Series, p. 318, 1996. 

Hostetler, K. A. and Thurman, E. M., Determination of chloroacetanilide herbicide metabolites in water using high performance liquid chromatography diode array detection and high performance liquid chromatography mass spectrometry. Set Total Environ., 248, 147-156, 2000. 

With few exceptions, herbicides are subject to metabolic transformations both in weed and crop species, after they have penetrated the plant tissue and are under way to their target site. As a rule, the herbicide metabolites are more polar than the herbicidal parent compound, and they exhibit reduced phytotoxicity or are completely non-phytotoxic. While often the first step of herbicide metabolism entails a partial or total detoxification of the parent compound, there are other cases where the herbiddaDy active form is generated in the first metabolic reaction (e.g., the hydrolysis of the inactive fenoxaprop-P-ethyl to the herbicidally active free add fenoxaprop-P) followed by detoxification of the molecule in the subsequent metabolic step. 

From the presented research data herbicide safeners obviously act in crops predominantly by enhancement of herbicide metabolism to non-phytotoxic degradation products. Notably, all safeners investigated so far only influenced the rate of herbicide metabolism, but did not alter the metabolic pathway. Hence safeners never altered the pattern of herbicide metabolites, but only led to quantitative shifts in the ratios between the phytotoxic parent compound and the metabolites of the herbicide, when compared with control plants without safener application. These quantitative differences between plants with and without safener treatment... 

Kawahigashi H, Hirose S, Ohkawa H, Ohkawa Y (2003) Transgenic rice plants expressing human CYPlAl exude herbicide metabolites from their roots. Plant Sci 165 373-381... 

In aquifers of the midwestem U.S., some of these herbicide metabolites have been detected more frequently and at higher concentrations than the parent molecule (3). Researchers in Wisconsin reported that alachlor, metolachlor, and acetochlor were detected in 20 and 40% of monitoring and private wells tested, respectively, while only 2% of the municipal sanq les contained these herbicides... 

Rheineck, B. and J. Postle. Chloroacetanilide Herbicide Metabolites in Wisconsin Groundwater Final Report. 9 pgs. Wisconsin Department of Agriculture, Trade and Consumer Protection. 2001. www.soils.wisc.edu/extension/FAPM/proceedings01 (Accessed June, 2002). 

Mio, S. R. Ichinose, K. Goto S. Sugai Synthetic studies on (+)-hydantocidin (1) a total synthesis of (+)-hydantocidin, a new herbicidal metabolite from microorganism. Tetrahedron 47,2111-2120,(1991)... 

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