Studies On Photodegradation Of Monosulfuron

The photochemical degradation of Monosulfuron irradiated by high pressure mercurylamp (HPML), ultraviolet light and sunlight was investigated. The effects of different typesof water, dissolved oxygen on the photodegradation of Monosulfuron in aqueous solutionwere studied. By GC-MS, photoproducts of Monosulforn in acetonitrile was detected. Thepathway of Monosulfron photodegradation in acetonitrile under HPML was proposed..1. The analytical method of monosulfuron by HPLC was established. A column ofstainless steel packed with ODS 5μm with 250mm×4.6mm was utilized.The operationparameters were optimized as: mobile phase, methanol/water=55/45(V/V) ,flow rate,0.8ml/min , a UV detection with wavelength of 254nm.2. The photodegradation rate of Monosulfuron in aqueous solution or on glass surfaceby HPML is not very quickly, the half-life was 147min on glass surface. And thephotolysis of Monosulfuron follows the first order kinetics.3. The results showed that Monosulfuron was very stable in water under sunlight, thehalf-lives of Monosulfuron under sunlight is 7.32d.But with the HPML and ultraviolet lightsources, the photolysis rates of Monosulfron ranged samely as:redistilled water > Tappedwater> river water(Dongpu reservoir) > lake water(Chaohu Lake). The half-lives ofmonosulfuron extended to7.62～9.64h under irradiation of ultraviolet light from 3.05～4.86h under HPML.4. Dissolved oxygen can greatly promote the photodegradation of Monosulfuron. UnderHPML irradiation, with the role of dissolved oxygen, the photolysis rates of monosulfuronwere improved about 3.411 times and the half-life shortened to 0.894 hour from 3.05 hour withoutaerifying O₂.5. Dissolve Monosulfron into acetonitrile then put this liquor under HPML. Spot the liquorwhich had been irradiated under HPML on surface of silica gel. Outspread the silica gelboard with the liquor that its compound is trichloromethane: methyl alcohol: acetone:ammonia=10:2:2:0.5 . And this liquor could separate monosulfuron with its product 1 ofphotodegradation. The Rf of Monosulfron is 0.47 while the product 1 is 0.95. 6. The photoproduct of Monosulfron in acetonitrile were identified by GC-MS, obtainedone photoproduct of Monosulfron in aqueoussolution under HPML, its molecular weightsis 202, with molecularstructure as follows:...