Effects of light on sulphonylurea herbicides, triasulfuron and thhifensulfuron methyl, were studied under UV and solar simulator irradiations. energies of first singlet and triplet state transitions were calculated from fluorescence spectra. Experiments were performed in the presence of either a singlet or a triplet quencer showing that photodegradation of both herbicides begins from a triplet state T1. Samples were irradiated and the disappearance of herbicides at various illumination times were determined by liquid chromatography, as compared to control solutions kept in the dark. The photolysis process of both herbicides occurred throught first order kinetic reactins. Halflife times were 22.3 and 54 hours for triasulfuron and thyfensulfuron methyl, respectively. The main products, identified by LC ESI mass spectroscopy, were: (4-methoxy-6-methyl-1,3,5-triazion-2-yl)urea, common to triasulfuron and thyfensulfuron methyl; 2-(2-chloroetoxy)benzenesulfonamide, arising from triasulfuron degradation; methyl(2-sulfonamide)thyofene carboxylate, occurring from thyfensulfuron-methyl transformation. the presence of minor by-products was also ascertained
Light irradiation and transformation of some sulfonylurea herbicides.
SCRANO, Laura;BUFO, Sabino Aurelio;D'AURIA, Maurizio;
2004-01-01
Abstract
Effects of light on sulphonylurea herbicides, triasulfuron and thhifensulfuron methyl, were studied under UV and solar simulator irradiations. energies of first singlet and triplet state transitions were calculated from fluorescence spectra. Experiments were performed in the presence of either a singlet or a triplet quencer showing that photodegradation of both herbicides begins from a triplet state T1. Samples were irradiated and the disappearance of herbicides at various illumination times were determined by liquid chromatography, as compared to control solutions kept in the dark. The photolysis process of both herbicides occurred throught first order kinetic reactins. Halflife times were 22.3 and 54 hours for triasulfuron and thyfensulfuron methyl, respectively. The main products, identified by LC ESI mass spectroscopy, were: (4-methoxy-6-methyl-1,3,5-triazion-2-yl)urea, common to triasulfuron and thyfensulfuron methyl; 2-(2-chloroetoxy)benzenesulfonamide, arising from triasulfuron degradation; methyl(2-sulfonamide)thyofene carboxylate, occurring from thyfensulfuron-methyl transformation. the presence of minor by-products was also ascertainedI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
