Photochemical Degradation of Imazamox in Aqueous Solution: Influence of Metal Ions and Anionic Species on the Ultraviolet Photolysis

Imazamox [5-methoxymethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid] is one of the later pesticides of the imidazolinone family. The fate of imazamox has been studied upon UV irradiation. The degradation of a 10 mg L-1 imazamox solution leads to pyridine derivatives, which remain in solution for 50−100 h. Most of the photoproducts occurring during the photodegradation have been characterized by means of liquid chromatography coupled with mass spectrometry. The degradation scheme is very similar to that observed for the analogous imazapyr pesticide [2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid]. Nevertheless, imazamox shows a greater stability than imazapyr. More, complexation interactions between imazamox and metal ions such as Cu2+ or Ca2+ increase the persistence of the pesticide. Keywords: Imazamox; imidazolinone; photodegradation; complex