title: Photodegradation and stability of chlorothalonil in water studied by solid-phase disk extraction, followed by gas chromatographic techniques.
abstract: Photodegradation of chlorothalonil was studied in deionized and ground water with sunlight and Suntest apparatus, with and without FeCl3/H2O2 and TiO2/H2O2. After irradiation of the water samples spiked at 28-100 micrograms/l of chlorothalonil, the water solutions were preconcentrated using solid-phase disk extraction with C18 and analyzed by gas chromatography-electron capture and gas chromatography-mass spectrometric detection. The degradation products identified by GC-MS were: trichloro-1,3-dicyanobenzene, dichloro-1,3-dicyanobenzene and chloro-1,3-dicyanobenzene. The degradation kinetics followed a first order reaction and the R.S.D. of rate constants, for n = 3, varied from 2 to 14%. Halflives varied between 0.7 and 101 h. The stability of chlorothalonil on C18 Empore disks was also investigated at 20 degrees C, 4 degrees C and -20 degrees C for periods of up to 3 months. Chlorothalonil was not degraded on C18 Empore disks.
authors.affiliation: Department of Environmental Chemistry, CID-CSIC, Barcelona, Spain.
authors.forename: G A
authors.initials: GA
authors.lastname: Peñuela
authors.forename: D
authors.initials: D
authors.lastname: Barceló
mesh_terms: D002712:Chlorides; D002849:Chromatography, Gas / Q000379:methods*; D004355:Drug Stability; D005290:Ferric Compounds / Q000494:pharmacology; D005659:Fungicides, Industrial / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008027:Light; D009570:Nitriles / Q000737:chemistry*; D010777:Photochemistry; D014025:Titanium / Q000494:pharmacology; D014867:Water / Q000737:chemistry*
chemical_list: D002712:Chlorides; D005290:Ferric Compounds; D005659:Fungicides, Industrial; D009570:Nitriles; D014867:Water; C009495:titanium dioxide; D006861:Hydrogen Peroxide; D014025:Titanium; C005806:tetrachloroisophthalonitrile; C024555:ferric chloride