Photodegradation of Norflurazon in water

Abstract

An important pathway governing the fate of herbicides is through photochemical degradation, either in the solid state or in aqueous solution. Norflurazon is a pre‐emergent herbicide which is widely used for weed control in vineyards in South Australia. The photochemical degradation of norflurazon in Milli‐Q water, Milli‐Q water containing 20 ppm of hydrogen peroxide, and natural water taken from the river Murray, has been investigated. Photolysis experiments were conducted in February and April under incident solar irradiation in borosilicate glass flasks. Photoproducts were isolated using solid phase extraction techniques and analysed by GLC‐NPD or GC‐MS. Under the influence of higher intensity radiation found in February there was no difference in breakdown rate of norflurazon in the presence or absence of hydrogen peroxide. However in April the breakdown rate was much slower without hydrogen peroxide. Four photoproducts have been identified.