Photodegradation of Cytrolane (mephosfolan) systemic insecticide in the aquatic environment using carbon-13 as a mass tracer

Article abstract of DOI:10.1021/jf60225a021

Photodegradation of mephosfolan (Cytrolane, a registered trademark of the American Cyanamid Co.) was studied by exposing approximately equimolar mixtures of either ¹²C/¹³C-imido-labeled or ¹²C/¹³C-ethyl-labeled material to sunlight. Use of the ¹²C/¹³C mixtures facilitated identification of photoproducts by gas chromatography chemical ionization mass spectroscopy (GC-CIMS) because molecular and fragmentions in the mass spectra appear as doublets. Solvent artifacts and volatile rice paddy water constituents gave mass spectra containing only singlet ions and were ignored. Irradiations were conducted in distilled water, 'natural' water obtained from a flooded rice paddy, and a 2% acetone-water solution. The half-lives for mephosfolan were 18, 14, and 7 days, respectively, and indicated that photosensitization by paddy water constituents and acetone was occurring. The major products identified were cyclic S,S-propylene dithiocarbonate, 2-imino-5-methyl-1,3-dithiolane, and diethyl phosphate. Minor products were ethyl phosphate, phosphoric acid, and diethyl methyl phosphate.