Paraoxon and parathion

Optical (400 nm) Cross-linking with BSA md GA in a Byodine nylon membrane 10 pM paraoxon and parathion 10 min steady response >10 days [270]... 

Ehrich et al. (1995) further determined NTE and AChE activities in SY5Y cells differentiated with retinoic acid or NGF after treatment with paraoxon, DFP, parathion, and inipafox. SY5Y cells differentiated with retinoic add show similar AChE and NTE inhibition by DFP, paraoxon, and parathion compared to cither undifferentiated or NGF-differcntiatcd cells. However, mipafox-induced inhibition is much lower in retinoic acid-differentiated cells. These findings suggest that SY5Y cells differentiated with NGF... 

To evaluate the overall oxidation reaction of parathion, the kinetics of chemical hydrolysis of parathion and paraoxon first had to be investigated. Then the kinetics of chemical oxidation of p-nitrophenol, paraoxon, and parathion were studied with KMn04. This oxidant was chosen partially because of its accepted use to reduce tastes and odors caused by organic compounds 31, 32, 33, 34) potassium permanganate also is easily applied, and its reduction products are filtered from the finished water. Chlorine and chlorine dioxide were tested for their efiiciencies in oxidizing parathion and paraoxon. 

The first reported pesticide hydrolyses by an organometallic complex, which are the paraoxon and parathion hydrolysis by the aqueous molybdenocene dichloride (CP2M0CI2), have been reported. The synthesis and structural characterisation of a new one-to-one charge-transfer salt ferromagnet which is constructed from decamethylchromocene and dimethylcyanofumarate have been... 

In a study of the metabolism of methyl parathion in intact and subcellular fractions of isolated rat hepatocytes, a high performance liquid chromatography (HPLC) method has been developed that separates and quantitates methyl parathion and six of its hepatic biotransformation products (Anderson et al. 1992). The six biotransformation products identified are methyl paraoxon, desmethyl parathion, desmethyl paraoxon, 4-nitrophenol, />nitrophenyl glucuronide, and /wiitrophenyl sulfate. This method is not an EPA or other standardized method, and thus it has not been included in Table 7-1. 

Blasiak J, Kowalik J. 1999. Effect of paraoxon-methyl and parathion-methyl on DNA in human lymphocytes and protective action of vitamin C. Pestic Sci 55 1182-1186. 

Singh S, Eehmann-Grube B, Boedde HW. 1984. Cytogenetic effects of paraoxon and methyl-parathion on cultured human lymphocytes SCE, clastogenic activity and cell cycle delay. Int Arch Occup Environ Health 54 195-200. 

FIGURE 2.1 Reaction scheme for OPH hydrolysis of methyl parathion and paraoxon (a) followed by the electrochemical oxidation of p-phenol (b). R and R are ethoxy and methoxy and X is O and S in paraoxon and methyl parathion, respectively. 

MWNTs favored the detection of insecticide from 1.5 to 80 nM with a detection limit of InM at an inhibition of 10% (Fig. 2.7). Bucur et al. [58] employed two kinds of AChE, wild type Drosophila melanogaster and a mutant E69W, for the pesticide detection using flow injection analysis. Mutant AChE showed lower detection limit (1 X 10-7 M) than the wild type (1 X 10 6 M) for omethoate. An amperometric FIA biosensor was reported by immobilizing OPH on aminopropyl control pore glass beads [27], The amperometric response of the biosensor was linear up to 120 and 140 pM for paraoxon and methyl-parathion, respectively, with a detection limit of 20 nM (for both the pesticides). Neufeld et al. [59] reported a sensitive, rapid, small, and inexpensive amperometric microflow injection electrochemical biosensor for the identification and quantification of dimethyl 2,2 -dichlorovinyl phosphate (DDVP) on the spot. The electrochemical cell was made up of a screen-printed electrode covered with an enzymatic membrane and combined with a flow cell and computer-controlled potentiostat. Potassium hexacyanoferrate (III) was used as mediator to generate very sharp, rapid, and reproducible electric signals. Other reports on pesticide biosensors could be found in review [17],... 

Other enzymes have also been immobilized on CNTs for the construction of electrochemical biosensors. Deo et al. [115] have described an amperometric biosensor for organophosphorus (OP) pesticides based on a CNT-modified transducer and OP hydrolase, which is used to measure as low as 0.15 pM paraoxon and 0.8 pM parathion with... 

Dieldrin, the oxidative metabolite of aldrin, was the most toxic of all insecticides in this study but was only slightly more toxic than its parent compound. The oxidative metabolites of parathion and malathion, paraoxon and malaoxon, were slightly less toxic than their parent compounds. 

Walter Reed-Wistar and Charles River male adult rats were exposed to oral doses of turpentine or to turpentine vapors, which consisted of a- and p-pinene. These exposures were followed by oral administration of heptachlor epoxide or of one of three pesticides, paraoxon, heptachlor, or parathion, or by an intraperitoneal injection of hexobarbital. The studies revealed that pretreatment with turpentine reduced hexobarbital sleeping time, reduced the parathion LDso, and increased the heptachlor LDso. The paraoxon and heptachlor epoxide LOo values were unchanged. a-Pinene and P-pinene vaporized from turpentine had no effect on either hexobarbital sleeping time or parathion, paraoxon, or heptachlor epoxide mortality but did increase the heptachlor LDso (Sperling et al. 1972). The authors speculated that increases in hepatic microsomal enzyme activity are responsible for these differences. 

Ozone and UV light alone cannot oxide parathion. However, in the presence of ozone (300 ppb) and UV light, dry kaolinite clays were more effective than the montmorillonite clays in the oxidation of parathion. The Cu-saturated clays were most effective oxidizing parathion to paraoxon and the Ca-saturated clays were the least effective (Spencer et al., 1980). 

When applied as thin films on leaf surfaces, parathion was converted to paraoxon and 4-nitrophenol. The photodegradation half-life was reported to be 88 h (HSDB, 1989). 

Ozonation of organophosphorous pesticides led to the formation of oxon intermediates (diazooxon, methyl paraoxon, and paraoxon for diazinon, methyl parathion, and parathion, respectively) [116]. These compounds accumulated to a different extent as a function of the solution pH. 

Table III. Afternoon Air Residues (ng/m ) and Paraoxon (PO) Parathion (PS) Ratios from Hivol XAD-4 Sampling within a Plum Orchard and 100 m Downwind Following Treatment with Parathion — 1975a...

Main, A.R. (1956). The role of A-esterase in the acute toxicity of paraoxon, TEPP and parathion. Can. J. Biochem. Physiol. 34 197-216. 

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