Phenoxy acid herbicides

Electrospray ionization (ESI) and APCI are the two popular API techniques that will be discussed here. The applications to the analysis of pesticides that will be discussed include imidazolinone herbicides, phenoxy acid herbicides, and A-methyl carbamate insecticides. Matrix effects with respect to quantitation also will be discussed. Eor the... 

ESI performs well for the more polar compounds such as imidazolinone herbicides, sulfonylurea herbicides, triazine herbicides, phenoxy acid herbicides, and carbamate pesticides (to name a few). ESI also performs well with proteins and peptides. 

Microwave Extraction of VOC s and SVOC s (organophosphorus pesticides, organochlorine pesticides, chlorinated herbicides, phenoxy acid herbicides, PCBs, etc.), EPA Method 3546, EPA SW-846 update III, US Environmental Protection Agency, 1999. 

Priority herbicides including triazines, and chloroacetanilides Four groups of pesticides including triazines Phenoxy acid herbicides Phenoxy acid herbicides Triazines and... 

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. 

Occupational and environmental exposure to chemicals can take place both indoors and outdoors. Occupational exposure is caused by the chemicals that are used and produced indoors in industrial plants, whereas nonoccupa-tional (and occupational nonindustrial) indoor exposure is mainly caused by products. Toluene in printing plants and styrene in the reinforced plastic industry are typical examples of the two types of industrial occupational exposures. Products containing styrene polymers may release the styrene monomer into indoor air in the nonindustrial environment for a long time. Formaldehyde is another typical indoor pollutant. The source of formaldehyde is the resins used in the production process. During accidents, occupational and environmental exposures may occur simultaneously. Years ago, dioxin was formed as a byproduct of production of phenoxy acid herbicides. An explosion in a factory in... 

Buser H-R, MD Muller (1997) Conversion reactions of various phenoxyaUcanoic acid herbicides in soil 2 elucidation of the enantiomerization process of chiral phenoxy acids from incubation in a DjO/soil system. Environ Sci Technol 31 1960-1967. 

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. 

Di Corcia and Marchetti [160] determined chlorinated phenoxy acid and ester type herbicides in amounts down to lmg kg-1 or lower in soil by liquid chromatography combined with particle beam mass spectrometry and ultraviolet absorption spectrometry. 

Otsuka, K., Smith, C. J., Grainger, J., Barr, J. R., Patterson, J., Tanaka, N., and Terabe, S. (1998). Stereoselective separation and detection of phenoxy acid herbicide enantiomers by cyclodextrin-modified capillary zone electrophoresis-electrospray ionization mass spectrometry. /. Chromatogr. A 817, 75-81. 

Studies were initiated at Iowa State University in 1977 to determine if pesticides would be contained and degraded when deposited in water/soil systems. Although the addition of known amounts of the selected pesticides was controlled, the physical environment was not temperature, humidity, wind speed, etc. were normal for the climate of Central Iowa. Four herbicides and two insecticides were chosen on the basis of three factors. Firstly, they represented six different families of pesticides. The four herbicides, alachlor, atrazine, trifluralin, and 2,4-D ester, represent the acetanilides, triazines, dinitroanilines, and phenoxy acid herbicides, respectively. The two insecticides, carbaryl and para-thion, represent the carbamate and organophosphorus insecticides, respectively. Secondly, the pesticides were chosen on the basis of current and projected use in Iowa Q) and the Midwest. Thirdly, the chosen pesticides were ones for which analytical methodology was available. 

M Studies on phenoxy acid herbicides. I. Field Study Occupational exposure to phenoxy acid herbicides (MCPA, Dichloro-prop, Meco-prop, and 2,4-D) in agriculture. Arch Toxicol 1983... 

Dichlorophenol and 2,4,5-trichlorophenol have been used in the synthesis of phenoxy acid herbicides, including 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-tri-chlorophenoxyacetic acid (2,4,5-T). 2,4,5-Trichlorophenol has also been used as a fungicide and a bactericide. 2,4,6-Trichlorophenol has been used as a pesticide. 2,3,4,6-Tetra-chlorophenol has been used as a fungicide (Lewis, 1993 Verschueren, 1996). Chlorophenols have also been formulated and used as salts in some applications. 

According to the 1990-93 CAREX database for 15 countries of the European Union (Kauppinen et al., 1998) and the 1981-83 National Occupational Exposure Survey (NOES) in the United States (NOES, 1997), approximately 45 000 workers in Europe and as many as 27 000 workers in the United States were potentially exposed to pentachlorophenol (see General Remarks). Recent figures give rough estimates of 500 pentachlorophenol-exposed workers in wood treatment facilities in the United States (Norman, 1998). No current data on numbers of workers exposed to other chlorophenols were available. Occupational exposures to chlorophenols have occurred in their production, in the production and use of some phenoxy acid herbicides, in sawmills and other wood-related industries, the textile industry and tanneries. Occupational exposures to penta-... 

Associations with chlorophenols were, however, analysed in two case-control studies nested within 24 of the 36 cohorts of the lARC study. These compared 11 cases of soft-tissue sarcoma and 32 cases of non-Hodgkin lymphoma with 55 and 158 controls, respectively (Kogevinas et al., 1995). Exposure to chlorophenols, phenoxy acid herbicides, dibenzodioxins and -furans and other agents was assessed by a team of industrial hygienists (Kauppinen et al., 1994). Odds ratios for non-Hodgkin lymphoma, not adjusted for exposure to other agents, were 1.3 (95% CI, 0.5-3.1) for any chlorophenol, 2.8 (0.5-17.0) for pentachlorophenol and 1.0 (0.3-3.1) for 2,4-dichlorophenol. No excess risk was found in relation to other chlorophenols, but the munber of exposed cases was small. The odds... 

Exposures to chlorophenols and their salts have occurred in their production, in the production of some phenoxy acid herbicides, in the wood industry, the textile industry and tanneries. They have been detected at low levels in ambient air and water. 

PAHS, organochlorine insecticides, benzene, uracil herbicides, carbamates, acid amides, phenoxy herbicides, pentachlorophenol, penzene, DCPB, organophosphate esters, PCBs, ethylene dibromide... 

The only phenoxy-acid herbicides to have significant current agricultural use in the USA are 2,4-D, esters of 2,4-D, and MCPA [79]. The total amount of phenoxy compounds used in the US agriculture has remained stable over the last two decades [79]. In Ontario, 2,4-D, MCPA, MCPB, mecoprop, and dicamba accounted for about 10% of the herbicide used in agriculture in 1998 [2], A 1993 pesticide usage survey carried out in Ontario indicated urban applications of phenoxy-acid herbicides similar to agricultural usage [76]. 

The phenoxy-acid herbicide 2,4-D is used primarily on pasture land, hay, wheat, corn, and barley. However, it is also used heavily for lawn care in urban areas of Ontario, along with dicamba and mecoprop. 2,4-D is applied in several forms, including esters, salts, and the acid form. In water, the esters of... 

The acute toxicity of phenoxy-acid herbicides to humans and aquatic organisms is relatively low [87]. The USEPA maximum residue level for 2,4-D in drinking water is 70 000 ng/L, and the National Academy of Sciences has recommended a maximum concentration in water for protection of aquatic life of 3000 ng/L [78]. No Canadian guidelines for the protection of aquatic life and drinking water were exceeded (Table 8). 

Studies in animals and humans have shown that oral doses of phenoxy herbicides are rapidly absorbed and are excreted virtually completely as phenoxy acids in urine with a half-life of less than 1 day. 

Numerous studies on the metabolism of 2,1t-dichlorophenoxy-acetic acid (2,1+-D) and related herbicides in animals have shown that these chemicals are absorbed and distributed rapidly in the body, and are excreted, undegraded, relatively quantitatively in the urine within a week after administration (M Pharmacokinetic studies with 2,1+,5-T in rats and dogs (5.) and in humans (6J supported these findings, and demonstrated that rates of clearance from plasma and elimination in urine depend on dosage level, animal species, and chemical structure of the phenoxy acid being studied ( + ). Corresponding chlorinated phenol metabolites were detected only in ruminants (M or in trace amounts in urine of rats fed very high doses of phenoxy herbicides (7.) ... 

Chlorinated [407,408] and 2,4-dinitrophenoxy acid herbicides [409] have been determined. liquid chromatography particle beam mass spectrometry has been used as an analytical finish [408]. Crescenzi et al. [410] evaluated the feasibility of selectively and rapidly extracting herbicide residues in soils by hot water and collecting analytes with a Carbograph 4 solid-phase extraction cartridge set on-line with the extraction cell. Phenoxy acid herbicides and those non-acidic and acidic herbicides that are often used in combination with phenoxy acids were selected for this study. Five soil samples were... 

Messerer P, Zober A, Becher H. 1998. Blood lipid concentrations of dioxins and furans in a sample of BASF employees included in the IARC registry of workers exposed to phenoxy acid herbicides and/or chlorophenols. Environ Health Perspect 106 (Suppl 2) 733-735. 

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