Parathion-ethyl

Chemical Designations - Synonyms 0,0-Diethyl 0-(p-nitrophenyl) phoshorothioate 0,0-Diethyl O-(p-nitrophenyl) thiophosphate Ethyl Parathion Phosphoroiioic acid 0,0-diethyl 0-p-nitrophenyl... 

The detection limits for 2,6-dinitroaniline herbicides are between 20 and 200 ng substance per chromatogram zone (Table 1). Similar results are also obtained with methyl and ethyl parathion (pink-colored zones). 

Mathematical models have also predicted a low volatility for methyl parathion (Jury et al. 1983 McLean et al. 1988). One study using a laboratory model designed to mimic conditions at soil pit and evaporation pond disposal sites (Sanders and Seiber 1983) did find a high volatility from the soil pit model (75% of the deposited material), but a low volatility for the evaporation pond model (3. 7% of the deposited material). A study of methyl parathion and the structurally similar compound ethyl parathion, which have similar vapor pressures, foimd that methyl parathion underwent less volatilization than ethyl parathion in a review of the data, the reduced level of volatilization for methyl parathion was determined to be due to its adsorption to the soil phase (Alvarez-Benedi et al. 1999). 

Production, Import/Export, Use, Release, and Disposal. Methyl parathion is commercially produced in the United States and abroad. Since 1977, production volume statistics for methyl parathion have been combined with those of ethyl parathion, also known as parathion. In 1983, the combined production capacity was estimated at 29 million kg for the United States and 10-15 million kg for western Europe (lARC 1983). Data on recent production in the United States were not located. In 1980,... 

Davis JE, Staiff DC, Butler LC, et al. 1977. Persistence of methyl and ethyl parathion following spillage on concrete surfaces. Bull Environ Contam Toxicol 18 18-25. 

Draper WM, Street JC. 1981. Drift from a commercial, aerial application of methyl and ethyl parathion An estimation of potential human exposure. Bull Environ Contam Toxicol 26 530-536. 

Morgan DP, Hetzler HL, Slach EF, et al. 1977. Urinary excretion of paranitrophenol and alkyl phosphates following ingestion of methyl or ethyl parathion by human subjects. Arch Environ Contam Toxicol 6 159-173. 

Smith S, Willis GH, McDowell EE, et al. 1987. Dissipation of methyl parathion and ethyl parathion from cotton foliage as affected by formulation. Bull Environ Contam Toxicol 39 280-285. 

Azinophos-ethyl Chlorphenvinfos Parathion-ethyl Parathion-methyl - + + + (+) (+)... 

V.B. Kandimalla, N.S. Neeta, N.G. Karanth, M.S. Thakur, K.R. Roshini, B.E.A. Rani, A. Pasha, and N.G.K. Karanth, Regeneration of ethyl parathion antibodies for repeated use in immunosensor a study on dissociation of antigens from antibodies. Biosens. Bioelectron. 20, 903-906 (2004). 

Additionally, they observed a second pathway, hydrolysis through dealkylation leading to a secondary ester of phosphoric acid which still contains the p-nitrophenyl moiety, i.e., de-ethyl Parathion (O-clhyl-O-p-nilrophenyl-monothiophosphoric acid) ... 

Most insecticides, especially the organophosphate group, cause neurotoxicity as their major mode of action. Assessment of the neurotoxicity includes neurochemical endpoints such as cholinesterase (including acetylcholinesterase, which is the major neurotransmitter in vertebrates such as fish, and other enzymes such as butyrylcholinesterase) inhibition and behavioral endpoints such as swimming speed [79]. Studies done in rats show the neurotoxic action of insecticides such as dimethoate, methyl parathion, dichlorvos, ethyl parathion or propoxur after a prolonged exposure [80,81]. 

Parathion degraded on both glass surfaces and on bean plant leaves. Metabolites reported were paraoxon, 4-nitrophenol, and a compound tentatively identified as 5-ethyl parathion (El-Refai and Hopkins, 1966). Upon exposure to high intensity UV light, parathion was altered to the following photoproducts paraoxon, 0,5-diethyl 0-4-nitrophenyl phosphorothioate, 0,0-diethyl 5-4-nitrophenyl phosphorothioate, 0,0-bis(4-nitrophenyl) 0-ethyl phosphorothioate, 0,0-bis(4-nitrophenyl) 0-ethyl phosphate, 0,0-diethyl 0-phenyl phosphorothioate, and 0,0-diethyl 0-phenyl phosphate (Joiner et al., 1971). 

Ethyl p-nitrophenyl benzenethionophosphate, see EPN Ethyl p-nitrophenyl benzenethiophosphonate, see EPN Ethyl p-nitrophenyl ester, see EPN Ethyl p-nitrophenyl phenylphosphonothioate, see EPN O-Ethyl O-4-nitrophenyl phenylphosphonothioate, see EPN O-Ethyl O-p-nitrophenyl phenylphosphonothioate, see EPN Ethyl p-nitrophenyl thionobenzenephosphate, see EPN Ethyl p-nitrophenyl thionobenzenephosphonate, see EPN Ethylolamine, see Ethanolamine Ethyl oxide, see Ethyl ether Ethyl parathion, see Parathion Ethylpentamethylene, see Ethylcyclopentane 2-Ethylpentane, see 3-Methylhextane O-Ethyl phenyl / nitrophenyl phenylphosphorothioate, see EPN... 

Ethyl-7-nitro-5-(trifluoromethyl)benzimidazole-3-oxide, see Trifluralin 5-Ethyl parathion, see Parathion 0,0-Ethyl-O-phosphorothioate, see Chlorpyrifos, Diazinon. Ronnel... 

The relative importance of the two processes in a model evaporation pond, along with the time lor 97% loss of the applied pesticide (system purification time), were calculated (Table V). This calculation confirmed that mevinphos and malathion dissipated primarily by hydrolysis, with malathion the more rapid of these two chemicals. For methyl and ethyl parathion, both processes were significant, although volatilization was the dominant dissipation route. However, since both processes were relatively slow for these pesticides, the purification time was fairly long. Diazinon was predicted to be lost primarily via volatilization, and the purification time was relatively short. 

The pesticides methyl and ethyl parathion were determined in run-off water er preconcentration on XAD-2. This allowed analyses of these compounds at the parts per billion level (497). Parathion and paraoxon obtained from leaf extracts and orchard soil have also been determined (492). The separation of 30 carbamate pesticides by RPC has been described (493). Various modes of postcolumn fluorometric detection of carbamate insecticides have been reported including post-colun)n reaction between o-phthalaldehyde and methylamine, a carbamate hydrolysis... 

For a risk assessment, see Evaluation of Ethyl Parathion as a Toxic Air Contaminant, California Department of Food and Agriculture (1988). 

Paraoxon, guthion, methyl parathion, fenitrothion, ethyl parathion... 

Water Azinphos methyl, dichlorvos, fenitrothion, malathion, mevinphos cis, mevinphos trans, chlorfenvinphos, diazinon, azinphos ethyl, fenthion, parathion ethyl, parathion methyl ... 

Water (E) Mevinphos, (Z) mevinphos, dichlorvos, azinphos methyl, parathion methyl, mala-thion, fenitrothion, azinphos ethyl, parathion, fenthion, chlorfenvinphos, diazinon ... 

Isocratic conditions have been established for HPLC with ultraviolet detection to determine trace levels of five pesticides frequently used in fruits, e.g., paraoxon, guthion, methyl-parathion, ethyl-parathion, and fenitrothion, in fruits and surface water (95). And HPLC was adapted for the determination of trace concentrations of seven OPP pesticides in drinking water. The analytes concentrated on the precolumn were eluted and separated on a C18 analytical column with an elution gradient program and determined by measuring their UV absorption (48). 

The use of LC-APCI-MS makes it possible unequivocally to identify various degradation products from fenitrothion, ethyl-parathion and methyl-parathion, fenthion, and temephos (42,44). Moreover, LC-APCI-MS provides the best information on the transformation products. 

In many instances, such as in studies of metabolism or degradation where the sensitivity is not so important, TLC and radioscanning provide a quick and simple technique for the identification and quantitation of radiolabeled metabolic products. An example of a radiochromatogram scan is shown in Fig. 2.13 for the analysis of some metabolites of the insecticide ethyl parathion in a microsomal enzyme preparation from rat liver [SI]. 

A reentry study 12 hr after application in Arizona cotton, exposing volunteers to methyl parathion, ethyl parathion, or monocrotophos for 5 hr produced no clinical signs of poisoning. However, cholinesterase depression averaged 147., and both ethyl-and methyl-parathion were found in the blood as well as p-nitrophenol (PNP) in the urine. These workers were not judged in jeopardy as cholinesterase depression was less than 307. and the PNP excretion was less than 4 mg following exposure (22). 

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