Persistence Behavior of Penoxsulam Herbicide in Two Different Soils

Penoxsulam, a new post emergence herbicide is suspected to be toxic to aquatic organisms, crop plants and also to soil microbial community even at low concentrations. Laboratory studies were therefore performed to examine the persistence of, penoxsulam in two different soils at two application rates (0.5 and 1.0 µg g^-1). The study revealed that the dissipation followed the first order kinetics with a half life of 3.48 and 3.57 days at 0.5 µg g^-1 and 4.1 and 4.17 days at 1.0 µg g^-1 fortification rate. Both microbial- and photo-degradation seemed to play a vital role in the dissipation of penoxsulam. The results of LC MS/MS revealed that one minor and five major metabolites were formed during the degradation process of the herbicide and the cleavage of sulfonamide bridge served as the major metabolic pathway.