2.4- dichlorophenoxy acetic acid

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. 

Dichlorophenoxy acetic acid (555ng) 12/ Indole-3-acetic acid ethyl ester (445ng)... 

Ogram AV, RE Jessup, LT On, PSC Rao (1985) Effects of sorption on biological degradation rates of (2,4-dichlorophenoxy)acetic acid in soils. Appl Environ Microbiol 49 582-587. 

It is important to keep in mind that any extraction of organic matter from soil will include both naturally occurring organic matter and organic contaminants. Separating the two at some later stage of analysis is thus an essential analytical step. For example, extraction of soil with hexane or dichloromethane will extract both l,l,l-trichloro-2,2-di(4-dicholorphenyl)ethane (DDT), a contaminant, and octadecanoic acid, a natural fatty acid. Also, the herbicide 2,4-dichlorophenoxy acetic acid, a contaminant, and indole-3-acetic acid, a natural plant hormone, are both extracted by water (see Figure 12.3). These... 

Renberg [154] has described a method for the determination of 2.4 dichlorophenoxy acetic acid (2.4D) and 2.4.5 tri chlorophenoxy acetic acid (2.4.5T) in soils in which the herbicide is derivativized to its methyl or 2-chloroethyl ester prior to determination by gas chromatography. Recoveries of the two herbicides at the 8-16mg kgp1 level in soil were between 70-74% (2.4D) and 84-86% (2.4.5T). 

Lopez-Avila et al. [159] used isotope dilution gas chromatography-mass spectrometry to determine low levels of pg kgy1 2,4 dichlorophenoxy acetic acid herbicide in soil. 

Kavetskii et al. [224] developed a method for the simultaneous determination of pesticides in soil. A combination of thin layer chromatography and gas chromatography was used. The pesticides examined were 4,4 DDT, 4,4 DDD, 4,4 DDE, 2,4 DDT, GHCG, aGHCG, Metaphos, Phosphamidon, Phozalone, Atrazine, Prometryne, Simazine and 2,4 dichlorophenoxy acetic acid. Detection limits were in the range 0.5-5pg kgy1. 

Acid herbicides such as 2,4 dichlorophenoxy acetic acid, 2,4,5-trichlorophenoxy acetic acid, 3,6-dichloropicolinic acid and other types of herbicides such as Dicamba, Dichloroprop, Picloram, Fenoprop, 2,3,6-TBA, Bromoxynil and Ioxynil are widely used in agriculture and are often formulated as mixtures. They may also be mixed in the spray tank or used in sequence, so it is likely that residues of more than one of these compounds may be present in the soil. 

Lawns also represent an urban ecological problem on a vast scale. In the United States, the chemicals of lawn maintenance-including dichlorophenoxy-acetic acid (2,4-D), glyphosate, diazinon, and dicamba-are significant contributors to nonpoint source water quality problems that continue to elude solution almost 30 years after the passage of the Clean Water Act. Lavm pesticides are applied on a scale to rival agricultural toxins 23% of the total 2,4-D applied in the United States is used on lawns 22% of glyphosate, 31% of chlorpyrifos, and 38% of dicamba used nationally is applied to home lavms. ... 

Dichlorophenol, see 2,4-Dichlorophenol 3-(3,4-Dichlorophenol)-l,l-dimethylnrea, see Dinron Dichlorophenoxyacetic acid, see 2,4-D (2.4-Dichlorophenoxy)acetic acid, see 2,4-D 3-(3,4-Dichlorophenyl)-l,l-dimethylnrea, see Dinron A -(3,4-Dichlorophenyl)-lV,lV-dimethylnrea, see Dinron Dichlorophos, see Dichlorvos a.p-Dichloropropane, see 1,2-Dichloropropane ds-l,3-Dichloropropene, see cis-l,3-Dichloropropylene frans-l,3-Dichloropropene, see ans-l,3-Dichloro-... 

Dichlorophenol. see a-BHC. Pentachlorophenol (2.5-Dichlorophenoxy)acetic acid, see 2.4.5-T (2.6-Dichlorophenoxy)acetic acid, see 2.4-D... 

Faust, S.D. and Aly, O.M. Evaluationof the solubilitiesofthe calcium and magnesium saltsof2,4-dichlorophenoxy acetic acid,... 

Que Hee, S.S., Sutherland, R.G., McKinlay, K.S., and Sara, J.G. Factors affecting the volatility of DDT, dieldrin, and dimethylamine salt of (2,4-dichlorophenoxy)acetic acid (2,4-D) from leaf and glass surfaces. Bull Environ. Contam. Toxicol, 13(3) 284-290, 1975. 

Several amperometric immunosensors have been developed for monoclonal antibodies (IgG), a-interferon and the pesticide 2,4-dichlorophenoxy-acetic acid (2,4-D) by using a flow-cell with the catching antibody covalently bound to a cellulose acetate or activated nylon membrane as shown in Fig. 3.31. B. With multiepitope antigens (e.g. a protein), after the antigen is bound and washed, a second enzyme-labelled antibody is used to form a sandwich... 

With deeper understanding of the rate laws applicable to these hydrolases, now we need to deduce the parameters that combine to give corresponding khl0 values for Michaelis-Menten cases (Eq. 17-80). We may now see that the mathematical form we used earlier to describe the biodegradation of benzo[f]quinoline (Eq. 17-82) could apply in certain cases. Further we can rationalize the expressions used by others to model the hydrolysis of other pollutants when rates are normalized to cell numbers (e.g., Paris et al., 1981, for the butoxyethylester of 2,4-dichlorophenoxy acetic acid) or they are found to fall between zero and first order in substrate concentration (Wanner et al., 1989, for disulfoton and thiometon). 

Rearrangements have been observed in the case of aryloxyacetic acids a-substituted by an aryl group (96, R = H, R2 = Ph, X = OH), which give 3-phenyl-2(3//)-benzofuranone (98).278 2,4-Dichlorophenoxy-acetic acid and its chloride do not undergo ring closure by any method.279... 

Often overlooked is the possibility that derivatization also provides qualitative information. For example, assume the suspect compound is a herbicide such as 2,4-D (2,4-dichlorophenoxy acetic acid). As such, this compound cannot be reasonably chromatographed and detected at trace levels. Therefore, it is customarily converted to the corresponding methyl ester and analysis is based upon comparison to standards of the corresponding methyl ester. The qualitative information available from this sequence is ... 

Dichlorophenoxy)acetic acid, together with the 2-methyl-4-chloro and the 2,4,5-trichloro analogs, 2-(2,4,5-trichlorophenoxy)propionic acid, and many other related compounds, constitute one of the major classes of herbicides, selective primarily to dicotyledonous plants. Monocotyledons,... 

Dichlorophenpxy) acetic acid-14C is metabolized by plant tissue to inactive, water-soluble substances, some of which regenerate the parent acid on hydrolysis. The rate of metabolism differs with different species, but is usually low in comparison with the indole or naphthalene auxins. One of the earlier studies described a single major metabolite in corn, wheat, peas, and tomatoes,121 the identity of which is still uncertain. In another study of differences between species which were susceptible and those which were resistant to the herbicide, the resistant red currant metabolized 50% of the carboxyl-labeled and 20% of the methylene-labeled (2,4 dichlorophenoxy)acetic acid to 14COi in seven days, whereas the susceptible black currant altered122 only 2%. Similar effects were found with apple varieties. Strawberry and lilac decarboxylated the herbicide readily however, 16 other species, of various susceptibilities to herbicide, were unable to decarboxylate the acid to any significant extent. In both varieties of currant, 5 to 10% of the herbicide was converted into water-soluble derivatives of the parent acid, and 10 to 30% was bound in the leaf tissue in an unextractable form. 

Two essentially different views of the metabolism of (2,4-dichloro-phenoxy) acetic acid have been presented. The first12 -124 was based on a 3tudy with bean stems, which converted 42% of (2,4-dichlorophenoxy)-acetic acid-l4C into acidic, water-soluble substances. Two ether-soluble metabolites were formed, and the same two metabolites could be recovered,... 

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