Photolysis of thin films of cypermethrin using in situ FTIR monitoring: Products, rates and quantum yields

Michal Segal-Rosenheimer, Yael Dubowski*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Cypermethrin is a synthetic pyrethroid insecticide commonly used both indoors and outdoors. Following its application, cypermethrin residues are exposed to atmospheric oxidants, such as ozone and OH radicals, as well as to solar radiation. The current work focuses on the photochemical degradation of cypermethrin under 254 nm, 310 nm, and solar radiation; including kinetic analysis, quantum yields, and identification of volatile and non-volatile products. The investigation was done using a combined FTIR set-up for parallel analysis of condensed and gas phases. Complementary GC-MS analysis was conducted on the pesticide's residues. Quantum yields of 0.41 and 0.25 were obtained under 254 and 310 nm, respectively. These values are in agreement with outdoor studies and are higher than the known yields for aqueous solution. The values obtained under all tested conditions suggest that photodegradation of adsorbed cypermethrin is a major outdoor degradation pathway. Oxygen presence was found to increase degradation rate and quantum yield. The identified photoproducts include 3-phenoxybenzaldehyde, 3-phenoxybenzoic acid, acetonitrile (m-phenoxyphenyl), and cypermethrin isomers on the surface and formic acid, CO2 and CO in the gas phase. The condensed phase products are more polar than the parent molecule, suggesting that they may be susceptible to a greater leaching rate in soils.

Original languageEnglish
Pages (from-to)262-269
Number of pages8
JournalJournal of Photochemistry and Photobiology A: Chemistry
Issue number2-3
StatePublished - 15 Dec 2008
Externally publishedYes


FundersFunder number
European Commission
Sixth Framework Programme


    • Cypermethrin
    • Pesticides
    • Photolysis
    • Photooxidation


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