Phenoxy acetic herbicides

Aroclor 1248, Aroclor 1254, and Aroclor 1260. Quantitation is by comparison of chromatograms with standard concentrations of pure compounds treated in an identical manner. The phenoxy acid herbicides (2,4-dichlorophenoxy)acetic acid (2,4-D), sUvex, and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) can be deterrnined by electron-capture detection after extraction and conversion to the methyl esters with BF.-methanol. The water sample must be acidified to pH <2 prior to extraction with chloroform. 

This technique has also been coupled with mass spectrometry for the partial identification of organic compounds eluted from the column, e.g. the determination of phenoxy acetic acid herbicides in soil and non-saline sediments. 

In sludge anionic and non-ionic surfactants carboxylic acids hhydroxybutyrate hydroxy valerate chloroaliphatic compounds chlorophenols polychlorobiphenyls 4-nitrophenol mixtures of organic compounds chlorinated insecticides, phenoxy acetic acid type herbicides and organotin compounds. 

Another growing technique is super-critical fluid chromatography. Recent references to soil analysis include the following applications aliphatic hydrocarbons, polyaromatic hydrocarbons, polychlorobiphenyls, dioxins, alkyl and aryl phosphates, chloro, organophosphorus, triazine, substituted urea, phenoxy acetic acid, Dacthal herbicides and insecticides and mixtures of herbicides and pesticides and mixtures of organic compounds. 

Renberg [35] used an ion-exchange technique for the determination of chlorophenols and phenoxy acetic acid herbicides in soil. In this method the soil extracts are mixed with Sephadex QAE A-25 anion exchanger and the adsorbed materials are then eluted with a suitable solvent. The chlorinated phenols are converted into their methyl ethers and the chlorinated phenoxy acids into their methyl or 2-chloroethyl esters for gas chromatography. 

Chau and Terry [146] reported the formation of penta-fluorobenzyl derivatives of ten herbicidal acids including 4-chloro-2-methyl-phenoxy acetic acid [145]. They found that 5h was an optimum reaction time at room temperature with pentafluorobenzyl bromide in the presence of potassium carbonate solution. Agemian and Chau [147] studied the residue analysis of 4-chloro-2-methyl phenoxy acetic acid and 4-chloro-2-methyl phenoxy butyric acid from water samples by making the pentafluorobenzyl derivatives. Bromination [148], nitrification [149] and esterification with halogenated alcohol [145] have also been used to study the residue analysis of 4-chloro-2-methyl phenoxy acetic acid and 4-chloro-2-methyl phenoxybutyric acid. Recently pentafluorobenzyl derivatives of phenols and carboxylic acids were prepared for detection by electron capture at very low levels [150, 151]. Pentafluorobenzyl bromide has also been used for the analytical determination of organophosphorus pesticides [152],... 

Waliszewski and Szynczynski [158] have described a gas chromatographic method for the determination of 4-chloro-2-methyl phenoxy acetic acid (MCPA) and 2.4 chloro phenoxy acetic acid (2.4D) herbicides in soils. The chlorophenoxy acetic acid herbicides were extracted from soil... 

Since the same effects occurred with the non-herbicidal (2,6-dichloro-phenoxy) acetic acid as with toxic compounds, glucose metabolic changes are not the important singular effects of auxin herbicides. 

Many other compounds have been included in studies on sucrose response. Most of these have been herbicides or enzyme poisons. None of the common herbicides had any positive effect on sucrose at rates up to that causing severe foliar injury. Earlier reports of response from 2-(2,4,5-trichlorophenoxy)propionic acid and 2,2-dichloropropionic acid could not be substantiated in British Guiana and Queensland. 27 Some compounds, such as 3-(p-chlorophenyl)-l,l-dimethylurea (monuron), (2,4-dichloro-phenoxy) acetic acid in soil, ethylenediaminetetraacetic acid, and leaf desiccants decreased sucrose and juice solids content. 20 Field trials with several chemicals in Trinidad showed enhanced sucrose at 14 to 28 days before harvest resulting from the application of 8 and 12 lb. (per acre) of... 

Dichloro-phenoxy acetic acid, 2,4,5- trichlorophenoxy acetic acid Herbicide derivatised to its methyl or 2-chlororethyl ester, then gas chromatography. 70 - 74% recovery [169]... 

See also Chlorophenoxy Herbicides 2,4-D (2,4-Dichioro-phenoxy Acetic Acid) Pesticides Poiiution, Water. 

Torstenson et al. (1975) published a nice example of adaptation of microflora to (2-methyl-4-chlorophenoxy) acetic acid (MCPA) and (2,4-dichloro-phenoxy) acetic acid (2,4-D). Soils from lots that had been treated with herbicides for 18, 1, and 0 (controls) years were used to inoculate a salt medium where 2,4-D or MCPA had been added as the carbon source (100 pM). The lag time before the degradation started was very much influenced by the type of inoculate, as shown by Figure 8.6 with data from Torstensson s work. 

Forgacs, E., Cserhati, T., and Barta, I., The binding of amino acids to the herbicide 2,4-dichloro-phenoxy acetic acid, Amino acids, 18, 69-79, 2000. 

Isolation and trace enrichment in off-line and on-line modes were described together with TSP-LC-MS determination of the spiked phenoxy acetic acid herbicides 2,4-dichlorophenoxy acetic acid (2,4-D), 4-chloro-2-methylphenoxy acetic acid... 

CE has been used for the analysis of chiral pollutants, e.g., pesticides, polynuclear aromatic hydrocarbons, amines, carbonyl compounds, surfactants, dyes, and other toxic compounds. Moreover, CE has also been utilized to separate the structural isomers of various toxic pollutants such as phenols, polyaromatic hydrocarbons, and so on. Sarac, Chankvetadze, and Blaschke " resolved the enantiomers of 2-hydrazino-2-methyl-3-(3,4-dihydroxyphenyl)propanoic acid using CD as the BGE additive. The CDs used were native, neutral, and ionic in nature with phosphate buffer as BGE. Welseloh, Wolf, and Konig investigated the CE method for the separation of biphenyls, using a phosphate buffer as BGE with CD as the chiral additive. Miura et al., used CE for the chiral resolution of seven phenoxy acid herbicides using methylated CDs as the BGE additives. Furthermore, the same group resolved 2-(4-chlorophenoxy) propionic acid (MCPP), 2-(2,4-dichlorophenoxy) propionic acid (DCPP), (2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chlorophenoxy) propionic acid (2,4-CPPA), [(2,4,5-... 

Phenoxy acid herbicides 0.1 M phosphate and acetate buffer containing OM and CDs 40... 

Crego and Marina [1] and Giibitz and Schmid [16] reviewed the chiral resolution of environmental pollutants by CE, and they described phosphate, borate, acetate, CHES and carbonate as suitable BGEs. Welseloh et al. [17] used a pH 2.4 30 mM phosphate buffer as the BGE for the chiral resolution of biphenyls. Mechref and El Rassi [40] resolved phenoxy acid herbicides using 175 mM phosphate (pH 6.5) [40] and 200 mM borate (pH 10.0) buffers [37] as BGEs. Furthermore, Tsunoi et al. [20] used a mixture of 0.1 M borate and 0.05 M phosphate buffers (pH 9.0) as BGE for the chiral... 

Figure 9.2 The effect of pH on the chiral resolution of phenoxy acid herbicides, using 100 mM sodium phosphate-sodium acetate buffers containing 60 mM OM as BGE. Other conditions as in Figure 9.1 [37],...

The answer is 3 [Chapter 28 tE 2c). The phenoxy acetic acid herbicides (e.g., 2,4-D) are plant hormones that cause changes in plant metabolism. Both er hancement of palpability and increases In toxin content (e.g., nitrates) have been demonstrated for some toxic plants treated with these herbicides. The other classes of heriMCkles also alter plant metabolism, but do not seem to affect toxin content or the response of animals to poisonous plants. 

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