Monitoring of malathion and its impurities and environmental transformation products on surfaces and in air following an aerial application

Brown, Mark A.; Petreas, Myrto; Okamoto, Howard S.; Mischke, Thomas M.; Stephens, Robert D.

doi:10.1021/es00039a020

Cited by 59 publications

(35 citation statements)

References 22 publications

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“…The results of our study show that malathion, its oxidation product malaoxon and its isomerisation product isomalathion inhibit free and immobilized AChE activities with varying potencies (Table I), as previously reported [5,6,8,10,25]. Since the inhibition powers of malathion and its inhibiting by-products were the same under the experimental conditions (within the range of experimental error) for the free and immobilized enzyme, it is obvious that immobilization of AChE on controlled pore glass did not affect its sensitivity to the investigated compounds, suggesting this may be a viable system to improve the speed of OP detection.…”

Section: Discussionsupporting

confidence: 89%

“…In addition to acute (short-term) toxic effects based on acetylcholinesterase inhibition, which leads to accumulation of acetylcholine, chronic low-level exposure to these compounds has been implicated as a causal factor in a variety of human diseases involving the nervous or immune systems [6,7]. Moreover, the toxicity of organophosphates is significantly increased by their break-down products, which may be bioactivated within an organism or through exposure to the sunlight [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…As malathion reacts and breaks down within an organism or upon exposure to sunlight, one of the chemicals released, malaoxon, is about 100 times more toxic than its parent compound [10]. The aim of our study was to apply two model systems based on inhibition of AChE for evaluation of the inhibitory power of malathion and the products of its photochemically-or chemically-induced transformations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inhibition of AChE by malathion and some structurally similar compounds

Krstić

Čolović

Kralj

et al. 2008

Journal of Enzyme Inhibition and Medicinal Chemistry

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Inhibition of bovine erythrocyte acetylcholinesterase (free and immobilized on controlled pore glass) by separate and simultaneous exposure to malathion and malathion transformation products which are generally formed during storage or through natural or photochemical degradation was investigated. Increasing concentrations of malathion, its oxidation product malaoxon, and its isomerisation product isomalathion inhibited free and immobilized AChE in a concentration-dependent manner. K I , the dissociation constant for the initial reversible enzyme inhibitor-complex, and k 3 , the first order rate constant for the conversion of the reversible complex into the irreversibly inhibited enzyme, were determined from the progressive development of inhibition produced by reaction of native AChE with malathion, malaoxon and isomalathion. .2) £ 10 26 M, were obtained from the inhibition curves induced by malathion, malaoxon and isomalathion, respectively. However, the products formed due to photoinduced degradation, phosphorodithioic O,O,S-trimethyl ester and O,O-dimethyl thiophosphate, did not noticeably affect enzymatic activity, while diethyl maleate inhibited AChE activity at concentrations . 10 mM. Inhibition of acetylcholinesterase increased with the time of exposure to malathion and its inhibiting by-products within the interval from 0 to 5 minutes. Through simultaneous exposure of the enzyme to malaoxon and isomalathion, an additive effect was achieved for lower concentrations of the inhibitors (in the presence of malaoxon/isomalathion at concentrations 2 £ 10 27 M/2 £ 10 27 M, 2 £ 10 27 M/3 £ 10 27 M and 2 £ 10 27 M/4.5 £ 10 27 M), while an antagonistic effect was obtained for all higher concentrations of inhibitors. The presence of a non-inhibitory degradation product (phosphorodithioic O,O,S-trimethyl ester) did not affect the inhibition efficiencies of the malathion by-products, malaoxon and isomalathion.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inhibition of AChE by malathion and some structurally similar compounds

Krstić

Čolović

Kralj

et al. 2008

Journal of Enzyme Inhibition and Medicinal Chemistry

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“…2-Mercapto-succinic acid diethylester was reported as an environmental transformation product of malathion (Brown et al, 1993). Bis(1,2-bis-ethoxycarbonyl-ethyl)disulfide may be produced by the oxidation of 2-mercapto-succinic acid diethylester, which is similar to the formation of bis(4-chlorophenyl)disulfide observed in the oxidation of O,O-diethyl-s-(4-chlorophenyl)phosphorodithioate (Miyamoto and Yamamoto, 1977).…”

Section: Resultsmentioning

confidence: 65%

“…Besides oxidation, the hydrolysis reaction can also take place during the degradation of malathion and chlorpyrifos and play an important role in their degradation in soil (Mulla et al, 1981;Miles and Takashima, 1991;Racke, 1993) and water (Mulla et al, 1981;Liu et al, 2001;Pehkonen and Zhang, 2002;Duirk et al, 2008). In the atmosphere, gas-phase malathion can be oxidized to malaoxon by atmospheric oxidants such as ozone, nitrate radicals and OH radicals (Brown et al, 1993). Malathion and chlorpyrifos can also be found in the particle phase in the atmosphere (Vincent et al, 1997;Van Dijk and Guicherit, 1999) due to their low vapor pressures (1.78 Â 10 À4 Pa for malathion and 2.5 Â 10 À3 Pa for chlorpyrifos at 25°C, respectively (Tomlin, 2006)).…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous ozonation of suspended malathion and chlorpyrifos particles

et al. 2010

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a b s t r a c tThe heterogeneous ozonation of suspended malathion and chlorpyrifos particles are studied in real-time with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The pesticide particles with the diameter of hundreds of nanometers are generated by the homogeneous nucleation method using azelaic acid as nucleus. The reactions are carried out in an aerosol reaction chamber under ambient pressure (1 atm) and room temperature (298 K), respectively. The time-of-flight mass spectra of the solid-state ozonation products of malathion and chlorpyrifos are obtained. The assignments of the mass spectra reveal that the major ozonation products of malathion particles are s-(1,2-diethoxycarbonyl)ethyl-O,O-dimethylphosphorothioate (malaoxon), 2-mercapto-succinic acid diethylester, 1,2-dicarbethoxyethyl-dimethoxyphosphinyldisulfide and bis(1,2-bis-ethoxycarbonylethyl)disulfide. The experimental results reveal that water vapor can enhance the formation of malaoxon, 2-mercapto-succinic acid diethylester and bis(1,2-bis-ethoxycarbonyl-ethyl)disulfide. In the case of chlorpyrifos, the sole ozonation product observed is 3,5,6-trichloro-2-pyridyl-diethylphosphate (chlorpyrifos oxon). The pathways of heterogeneous ozonation of malathion and chlorpyrifos particles are proposed. The atmospheric lifetimes of malathion and chlorpyrifos particles towards ozone reaction are estimated based on the time-dependent mass spectrometric signals obtained.

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Gas Chromatography/Mass Spectrometry Methods in Pesticide Analysis

Benfenati

Natangelo

Tavazzi

2000

Encyclopedia of Analytical Chemistry

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Gas chromatography/mass spectrometry (GC/MS) is irreplaceable in pesticide analysis. Nowadays international bodies consider mass spectrometry (MS) the method of choice for pesticide analysis and quantitative methods using GC/MS are more and more numerous. 1,2 The key characteristics of GC/MS in pesticide analysis are its selectivity and sensitivity, but other important features will be considered in detail in the specific sections on identification and quantitative analysis. A great advantage of GC/MS in identification is that it gives a mass spectrum that can be easily and quickly compared on‐line with a library of more than 200 000 mass spectra. Specific pesticide libraries are available with hundreds of compounds. Mass spectra can be obtained with just a few picograms of compound injected and gas chromatography (GC) can separate analytes. This is an unbeatable feature of GC/MS. In quantitative analysis, sensitivity is often excellent and selectivity is better than with other GC detectors. Multiresidue analyses can easily be done. The use of internal standards labeled with stable isotopes allows an accuracy which is not achieved with common methods. These characteristics facilitate sample processing because cleanup stages are not necessary in many cases. Major limitations in the use of GC/MS depend on GC limits. Thus, very polar and thermally labile pesticides, not suitable for GC analysis, cannot be analyzed by GC/MS. Other limitations are the cost of the apparatus and the relative complexity of the method, compared with the simpler GC detectors. However, these limitations are gradually becoming less important as GC/MS instruments become simpler and cheaper.

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Monitoring of malathion and its impurities and environmental transformation products on surfaces and in air following an aerial application

Cited by 59 publications

References 22 publications

Inhibition of AChE by malathion and some structurally similar compounds

Inhibition of AChE by malathion and some structurally similar compounds

Heterogeneous ozonation of suspended malathion and chlorpyrifos particles

Gas Chromatography/Mass Spectrometry Methods in Pesticide Analysis

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