Aqueous photodegradation of fenthion by ultraviolet B irradiation: contribution of singlet oxygen in photodegradation and photochemical hydrolysis

Hirahara, Yoshichika; Ueno, Hitoshi; Nakamuro, Katsuhiko

doi:10.1016/s0043-1354(02)00272-5

Cited by 36 publications

(25 citation statements)

References 26 publications

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“…This result perhaps indicated that acetamiprid photolysis did not go through a triplet excited state since O 2 was an excellent quencher of triplets and it could absorb the energy from triplet excited state to ground state, and inhibit the photolysis of pesticide. Many papers reported the effect of dissolved oxygen on pesticide photolysis (Hirahara et al 2003;Shirayama and Tohezo 2000).…”

Section: Resultsmentioning

confidence: 99%

Kinetics of Acetamiprid Photolysis in Solution

Xie

Liu

Sun

et al. 2008

Bull Environ Contam Toxicol

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Photolysis of acetamiprid was investigated in detail under different reaction conditions. The photolysis of acetamiprid in solution followed pseudo-first-order kinetics under the experimental conditions. Acetamiprid kept stable under irradiation of high-pressure xenon lamp but degraded relatively fast when exposure to medium-pressure mercury lamp irradiation. The experimental results indicated that the degradation rate of acetamiprid in acetone was the largest among the used media and acetamiprid was more stable in basic media. The addition of oxygen, increase of light intensity and temperature will enhance the photolysis.

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Section: Resultsmentioning

confidence: 99%

Kinetics of Acetamiprid Photolysis in Solution

Xie

Liu

Sun

et al. 2008

Bull Environ Contam Toxicol

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“…9) Thus it was indirectly suggested that 1 O 2 contributes to the photooxidative mechanism of fenthion and MMTP. In this study, 1 O 2 generation was directly detected using the ESR technique to clarify the photooxidation mechanism of fenthion in detail.…”

Section: Resultsmentioning

confidence: 99%

“…9) Aqueous photolysis mechanisms of fenthion were proposed on the basis of two kinds of reactions, one is pH-dependent photochemical hydrolysis of the phosphorus-O-phenyl ester (Fenthion → MMTP + Dimethyl phosphorothioate), and the other is oxidation of sulfide (Fenthion → Fenthion sulfoxide, MMTP → MMSP). 9) [10][11][12][13][14] The objective of this study was to elucidate the photooxidation mechanism of fenthion by 1 O 2 in detail. We therefore performed ESR analysis using TMPD to detect 1 O 2 directly which was generated in UV-irradiatied fenthion and its photodegradation products: MMTP, MMSP, dimethyl phosphorothioate and fenthion sulfoxide.…”

Section: -3)mentioning

confidence: 99%

Photooxidation Mechanism of Fenthion by Singlet Oxygen: Evidence by ESR Analysis with a Selective Spin Trapping Agent.

Hirahara

Okuno

Ueno

et al. 2003

JOURNAL OF HEALTH SCIENCE

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Our previous study suggested that UVB irradiation of the organophosphorus pesticide, fenthion and its photodegradation product, 3-methyl-4-methylthiophenol (MMTP) yielded fenthion sulfoxide and 3-methyl-4-methylsulfinylphenol (MMSP), and that the formation mechanism was related to generation of singlet oxygen ( 1 O 2 ). The objective of this study was to elucidate the 1 O 2 -triggered photooxidation mechanism of fenthion in detail. Generation of 1 O 2 in the photooxidative reaction was directly detected by electron spin resonance (ESR) technique with 2,2,6,6-tetramethyl-4-piperidone (TMPD) as a selective 1 O 2 spin trapping agent which yields 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (TEMPONE). When fenthion and MMTP solutions were irradiated by UVA or UVB light, the TEMPONE signal was observed. However, no signal was detected after exposure of MMSP, dimethyl phosphorothioate or fenthion sulfoxide solutions to the UV light. The production of the signal in fenthion and MMTP solutions was more predominant under UVB irradiation than under UVA irradiation. When the signal was detected in these solutions, fenthion sulfoxide and MMSP were also formed in amounts proportional to the signal intensity. The TEMPONE signal intensity and the formation of these oxidative products were significantly inhibited by the addition of 1 O 2 scavenger, L-histidine or sodium azide to the reaction medium. The study provided the first direct evidence that 1 O 2 is generated during photolysis of fenthion and MMTP by UV irradiation. We also proposed its oxidation mechanism of fenthion and MMTP.

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“…56) The photooxidation of a thioether moiety is one of the typical reactions of 1 O 2 , 9) and the successive transformation to sulf-oxide and sulfone was reported for some pesticides including OP's. 125) Several quenching studies 210) with the application of a spin trapping technique 65) in the aqueous photolysis of fenthion clearly showed the involvement of 1 O 2 in its oxidation to sulfoxide, and energy transfer from its T* to 3 O 2 was proposed by LFP. 43) A similar mechanism is most likely for S-oxidation of fenamiphos 4) and propaphos.…”

Section: Oxidationmentioning

confidence: 99%

Direct photolysis mechanism of pesticides in water

Katagi

2018

Journal of Pesticide Science

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Photodegradation is one of the most important abiotic transformations for pesticides in the aquatic environment, and the high energy of sunlight causes characteristic reactions such as bond scission, cyclization, and rearrangement, which are scarcely observed in hydrolysis and microbial degradation. This review deals with direct photolysis via excitation of a pesticide by absorbing natural or artificial sunlight in order to know its basic photochemistry, and indirect photolysis meaning either sensitization by dissolved organic matters or oxidation by reactive oxygen species is basically excluded. Several experimental approaches including spectroscopic techniques together with theoretical calculations are first discussed from the viewpoint of the reaction mechanisms in direct photolysis. Then, the typical photoreactions of pesticides are summarized by chemical classes and/or functional groups and discussed as far as possible in relation to their mechanisms.

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Aqueous photodegradation of fenthion by ultraviolet B irradiation: contribution of singlet oxygen in photodegradation and photochemical hydrolysis

Cited by 36 publications

References 26 publications

Kinetics of Acetamiprid Photolysis in Solution

Kinetics of Acetamiprid Photolysis in Solution

Photooxidation Mechanism of Fenthion by Singlet Oxygen: Evidence by ESR Analysis with a Selective Spin Trapping Agent.

Direct photolysis mechanism of pesticides in water

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