Photodegradation of organophosphorus insecticides – Investigations of products and their toxicity using gas chromatography–mass spectrometry and AChE-thermal lens spectrometric bioassay

Kralj, Mojca Bavcon; Franko, Mladen; Trebše, Polonca

doi:10.1016/j.chemosphere.2006.09.039

Cited by 119 publications

(55 citation statements)

References 39 publications

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“…Miyamoto and Yamamoto (1977) also reported the similar analogues from the oxidation of O,O-diethyl-s-(4-chlorophenyl)phosphorodithioate. Malaoxon, the main oxidation product of malathion, was observed in the ozonation and the degradation of malathion in water and soil (Laplanche et al, 1984;Reynolds et al, 1989;Miles and Takashima, 1991;Bavcon et al, 2003;Ikehata and El-Din, 2005;Bavcon Kralj et al, 2007;Zhao and Hwang, 2009). The mass peak at m/z 268 is assigned to C 8 H 13 O 6 PS + , the malaoxon daughter ion after losing ethanol (C 2 H 6 O) group during the VUV photoionization.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

confidence: 99%

Heterogeneous ozonation of suspended malathion and chlorpyrifos particles

et al. 2010

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“…Photodegradation of malathion in aqueous solution was performed by applying our previously published method [9]. A freshly prepared pesticide solution containing less than 0.5% ethanol was purged with oxygen for 15 min in the dark before irradiation, and was then put into a quartz sample cell (10 £ 10 £ 40 mm) and placed in front of a xenon light (125 W Cermax Xenon parabolic lamp) at a distance of 45 cm.…”

Section: Photodegradation Proceduresmentioning

confidence: 99%

“…Individual solution samples were irradiated for different periods of time (3.5 min, 7 min, 15 min, 30 min, 60 min or 120 min). The samples were analyzed by high performance liquid chromatography analysis (HPLC), ion chromatography (IC) and gas chromatography-mass spectrometry (GC-MS) [8,9]. The activity of AChE in the presence of pesticides after irradiation was as reported in the previous paper [8].…”

Section: Photodegradation Proceduresmentioning

confidence: 99%

“…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%

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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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“…FIA-AChE-TLS was also applied for monitoring the toxicity during the photodegradation of OPs and during photocatalytic processes, [53][54][55][56] as well as for the optimization of advanced oxidation methods for treating waters contaminated with OP insecticides. 57 The fast response of FIA-TLS along with actually no sample treatment before the analysis makes it possible to render analyses in 3 -5 min, and therefore provides a quasi-online monitoring of water-treatment processes that take 1 -2 h. The inhibition of AChE activity during such watertreatment processes indicates the formation of toxic degradation products (mainly OP oxons).…”

Section: Bioanalytical Applications Of Tls and Fia-tls Assaysmentioning

confidence: 99%