Abiotic Degradation of Iodosulfuron-methyl-ester in Aqueous Solution

Authors:
Publisher website
Google Scholar
Abstract
The abiotic degradation of iodosulfuron-methyl-ester was investigated under both alkaline and acidic pH conditions in the dark, and results showed it to be a rather stable molecule in neutral or slightly alkaline environments. Photochemical reactions were studied using a high-pressure mercury arc lamp, and results showed that direct phototransformation is possible under normal environmental conditions (λ > 290 nm). High-performance liquid chromatography (HPLC-UV and HPLC-MS) analyses were used to identify the degradates and to study the kinetics of photodecomposition and hydrolysis. Five main products of iodosulfuron-methyl-ester degradation were tentatively identified, and one of them (4-methoxy-6-methyl-1,3,5-triazin-2-amine) was confirmed using an authentic standard. Among the phototransformation mechanisms, photosubstitution of the iodide atom by a hydroxyl group, photodissociation of the N−S bond, and photoassisted hydrolysis were observed. The quantum efficiencies (multiwavelength quantum yield) of the photodegradation under different conditions were determined, and values of 0.054 ± 0.02 (pH 9.6), 0.08 ± 0.02 (pH 7), and 0.044 ± 0.008 (pH 5.3) were obtained. Keywords: Herbicide; iodosulfuron-methyl-ester; hydrolysis; photodegradation; quantum efficiency; HPLC-MS analysis

This publication has 10 references indexed in Scilit: