Herbicides silvex

DOUBLE STRENGTH FENOPROP FENORMONE FRUITONE T HERBICIDES, SILVEX KURAN KURON KUROSAL MILLER NU SET PROPON RCRA WASTE NUMBER U233 SILVEX (USDA) SILVI-RHAP STA-FAST 2,4,5-TC 2,4,5-TCPPA 2,4,5-TP... 

Analysis of Chloronhenoxv Herbicides. Many important target environmental pollutants can only be detected via conventional GC methods by first converting them to derivatives that are less polar and more volatile, e.g., the chlorophenoxy herbicides. A standard EPA method (SW-846 8150) specifies soil extraction and alkaline hydrolysis of any esters present followed by (re) esterification via diazomethane and detection and confirmation by GC/MS. The methylation step is required because the free carboxylic acids will not pass through conventional GC analytical columns. Reversed phase chromatography functions equally well to resolve free carboxylic acids or the corresponding esters and thus can eliminate the diazomethylation step. An interlaboratory check sample provided by the EPA of soil spiked with the chlorophenoxy acid herbicides Silvex and 2,4-D was obtained by our laboratory to demonstrate that LC/MS can offer a simpler and effective method for these compounds. 

TP (Silvex) 0.05 0.05 Liver problems Residue of banned herbicide... 

Source Although not produced commercially, TCDD is formed as a by-product in the synthesis of 2,4,5-trichlorophenol. TCDD was found in 85% of soil samples obtained from a trichlorophenol manufacturing site. Concentrations ranged from approximately 20 ng/kg to 600 g/kg (Van Ness et al, 1980). TCDD may be present in the herbicide 2,4-D which contains a mixture of dichloro-, trichloro-, and tetrachlorodioxins. TCDD is commonly found as a contaminant associated with pulp and paper mills (Boddington, 1990). In addition, during the manufacture of 2,4,5-T and silvex from trichlorophenol, TCDD was found at concentrations averaging 20 parts per billion (Newton and Snyder, 1978). 

Strong acids include battery acid, murintic acid, and hydrochloric acid. Weak acids include acetic acid, toilet bowl cleaner, and lactic acid. Banned pesticides include Silvex, Mirex, Aldrin, Chlordane, DDT, and Heptachlor. Caustics include oven cleaner and drain cleaner. Flammables include alcohol, acetone, turpentine, lacquer, and paint thinner. Pesticides include rodent poisons, insecticides, weed killer, and other herbicides and fungicides. Pesticide containers should be triple-rinsed, and the contents sprayed on crops or yard, before discarding. 

Dioxin (TCDD — 2,3,7,8-Tetrachlorodibenzoparadioxin) A by-product of Silvex herbicides production, more toxic than plutonium. 

T, in turn, was used in the production of a wide variety of herbicides including Silvex (2-[2,4,5-trichlorophenoxy]propionic acid) and Agent Orange (Hutzinger et al. 1985). Hexachlorophene, which is currently under EPA suspension, is reported to contain <15 g/kg (ppb) 2,3,7,8-TCDD (IARC 1977 Sine 1990). 2,3,7,8-TCDD is an unwanted by-product formed during the production of hexachlorophene (Freeman et al. 1986). The 2,3,7,8-TCDD produced is primarily contained in still-... 

Lee et al. [187] developed a multi-residue method with a low detection limit for 10 commonly used acid herbicides in non saline waters. The herbicides were Dicamba, MCPA, 2,4-DP, 2,3,6-TBA, 2,4-D, Silvex, 2,4,5-T, MCPB, 2,4,5-DB and Picloram. The method used solvent extraction and the formation of pentafluorobenzyl esters. The derivatives were quantified by capillary column gas chromatography with electron capture detection. The detection limit was 0.05pg L. Recoveries of herbicides from spiked Ontario lake water (0.5-1.Opg L 1) were 73-108% except for Picloram recovery which was 59% at 0.1 pg L 1. 

The nine herbicides studied by these workers were Dicamba, MCPA, MCPB, 2,4-DB, Picloram (4-amino-3,5,6-trichloropicolinic acid), 2,4-D, 2,4,5-T, Silvex and 2,4-DP. 

TP [2-(2,4,5-trichlorophenoxy propionic acid], or silvex, is an herbicide that has been used for weed and brush control on rangeland and rights of way. It is soluble in water and its environmental resistance is expected to be relatively short. 2,4,5-TP is contaminated to varying extents with 2,3,7,8-TCDD, a toxic polychlorinated dibenzo-/j-dioxin. It has been classified in the EPA s Group D (not classifiable). 

Trichlorophenols are generally poisons and may be carcinogens. They may contain 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a contaminant. Some trichlorophenols are used as herbicides (e.g., 2,4,5-T and silvex). Human exposure may cause chloracne, liver dysfuncdon, muscle weakness, and prophyria. 

The following are examples of priority pollutants arsenic, selenium, barium, cadmium, chromium, lead, mercury, silver, benzene, ethylbenzene, chlorobenzene, chloroethene, dichloromethane, and tetrachloroethene. The priority pollutants also include the pesticide and fumigant eldrin, the pesticide lindane, the insecticide methoxychlor, the insecticide and fumigant toxaphene, and the herbicide and plant growth regulator silvex. There are a total of 65 priority pollutants. 

These herbicides are highly selective for hroadleaved weeds. 2,4-D was the first chlorophenoxy acid herbicide developed. There are several compounds that belong to this group in addition to 2,4-D and they include 2,4-DB, Di-chlorprop, MPCA, MPCB, MCPP, 2,4,5-T, and 2,4,5-TP (Silvex). 

An interlaboratory comparison of the performance of thermospray and PBI LC-MS interfaces for the analysis of chlorinated phenoxyacid herbicides was reported by Jones et al. [94]. Except for Silvex, statistically significant differences were observed in the results from the two interfaces. PBI LC-MS exhibited a high positive bias, but a better %RSD at the highest concentration (500 pg/ml). A comparison of the official US-EPA method 515.1 for CPA analysis with on-line solid-phase extraction (SPE) in combination with GC with electron-capture detection (GC-ECD), LC-UV, and PBI LC-MS was reported by Bruner et al. [95]. In this method, liquid-liquid extraction (LLE), as prescribed in the US-EPA method, was replaced by SPE for sample preconcentration. In the LC methods, no derivatization was necessary. Detection limits were in the range of 0.07-0.8 ng/1 for GC-ECD, 0.7-7 ng/1 for PBI-LC-MS, and 6-80 ng/1 for LC-UV. The most accurate methods were LC-UV and GC-ECD, although PBI LC-MS is still more accurate than the US-EPA 515.1 method. 

Synthetic organic contaminants including pesticides and herbicides such as the following 2,4-D, 2,4,5-TP (Silvex), acrylamide, Alachlor, atrazine, benzoapyrene, carbofuran, Chlordane, dalapon, di-2-ethylhexyl adipate, di-2-ethylhexyl phtha-late, dibromochloropropane, Dinoseb, dioxin (2,3,7,8-TCDD), Diquat, Endothall, Endrin, epic-hlorohydrin, ethylene dibromide, glyphosate, He-ptachlor, Heptachlor epoxide, hexachlorobenzene. 

Figure 4. Reverse phase chromatogram with Particle Beam MS detection eluting with water/methanol (selected ion monitoring, El) of a soil extract containing the chlorophenoxy herbicides 2,4-D (Rj 2.6 min) and Silvex (Rt 5.2 min).

Although atrazine was regularly detected in Nebraska ground-water, 11 other pesticides were monitored, but not found (56). These included herbicides 2,4-D, EPTC, and silvex, and insecticides DDT, DDE, dieldrin, endrin, heptachlor, heptachlor epoxide, lindane, and methoxychlor. In this study, alachlor was found in 2 of 14 samples, 0.02 and 0.07 ppb similarly low residues of alachlor were found in 2 of 33 samples in another Nebraska study (55). 

Agricultural and wartime use of trichlorophenol-based herbicides such as 2,4,5-T and silvex also has resulted in release of... 

It is translocated relatively slowly from the leaves to the roots and tubers. Depending on temperature, light intensity and air and soil moisture, translocation proceeds in 4-8 days, the effect being manifested by chlorotic symptoms, which develop in 2-4 weeks into necrosis. Combined with other translocatable herbicides, such as 2,4-D, 2,4-DB or silvex, basipetal translocation and thus herbicidal action can be increased, and regrowth from tubers reduced. 

ORIGIN/INDUSTRY SOURCES/USES not produced or commercially used in U.S. formed in the production of 2,4,5-trichlorophenol and of a few chlorinated herbicides such as silvex formed during combustion of chlorinated organic compounds impurity in pesticides has been tested for use in flameproofing polyesters tested as an insecticide used as a defoliant in Vietnam War... 

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