Photodegradation of Irgarol 1051 in water

The photodegradation of a novel antifouling agent with high algicidal activ ity, Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-tria zine), has been investigated. Irgarol 1051 is fairly stable toward hydrolys is in water, and has been detected in European coastal and lake waters sinc e its introduction in the late 1980's. Irgarol 1051 dissolved in six differ ent aqueous solutions was exposed to solar irradiation for 6 months. Its ra tes of photodegradation in natural sea water and river water were much high er than those in pure water and buffered solutions (pH 5, 7, and 9). It app ears that unknown photosensitizers in the natural waters accelerated the ph otodegradation of Irgarol 1051. Three significant photodegradation products ("RT5.8", "RT7.8", and "RT8.7") were observed. The degradation product RT7 .8 was produced just in the natural waters and persisted for only several w eeks. The other two degradation products (RT5.8 and RT8.7) were much more s table, even after 6 months irradiation. The latter (RT8.7) was produced mai nly in buffer solutions, and the former (RT5.8) was produced in all the 6 a queous solutions tested and was identified by GC-MS analysis as the compoun d 2-methylthio-4-tert-butylamino-6-amino-s-triazine, which had been found a s a biodegradation product during the fungal biotransformation of Irgarol 1 051. Thus biodegradation and photodegradation processes in natural waters b oth have the same major degradation product.