Study of the Photodegradation Kinetics of Fluometuron by UV Absorption Spectrophotometry and Fluorescence

Abstract

In order to predict the fate of fluometuron in the aquatic environment and to assess the risk that it may pose, we studied its photolysis reaction in aqueous media. This reaction was monitored by UV absorption and fluorescence spectroscopy. UV irradiation source consisting of a 254 nm mercury lamp was used.  The study showed that fluometuron is unstable under the effect of light radiation when irradiated in water. The absorption band and the emission of this product were at 244 nm and 325 nm respectively. This study also shows that the photodegradation of fluometuron in water follows first order kinetics regardless of the method followed.  However, a difference was noted in the half-life times (t1/2). Indeed, these times found in UV and fluorescence are respectively 18.2 min and 6.6 min. The relatively lower value obtained in fluorescence could be explained by the fact that the latter is more sensitive to UV and fluorescence. In all cases, the half-lives found were relatively short (t1/2<1h). For more information on the photolysis of this herbicide, these two methods were combined with NMR and GC-MS to identify the different photoproducts that may be formed.