Imazethapyr Aqueous Photolysis, Reaction Quantum Yield, and Hydroxyl Radical Rate Constant

• Published in: Journal of agricultural and food chemistry 2006-04, Vol.54 (7), p.2635-2639
• Main Authors: Avila, Luis A, Massey, Joseph H, Senseman, Scott A, Armbrust, Kevin L, Lancaster, Sarah R, Mccauley, Garry N, Chandler, James M
• Format: Article
• Language: English
• Subjects: absorbance; aqueous solutions; Biological and medical sciences; Drug Resistance; Food industries; free radicals; Fundamental and applied biological sciences. Psychology; Herbicides - chemistry; hydroxyl radical; Hydroxyl Radical - chemistry; imazethapyr; Kinetics; Nicotinic Acids - chemistry; Oryza - growth & development; paddy soils; Photolysis; reaction kinetics; rice paddy water; water; Water - chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf052214b

The recent introduction of imidazolinone-tolerant rice varieties allow imazethapyr to be used in commercial rice. Little is known about imazethapyr photodegradation in the rice field. Laboratory studies were conducted to determine the direct and indirect photolysis rates for imazethapyr and to evaluate the photolysis of imazethapyr in three rice paddy waters. The reaction quantum yield (φ I) for imazethapyr was determined to be 0.023 ± 0.002, while the hydroxyl radical rate constant ( ) was 2.8 × 1013 M-1 h-1. These results show that imazethapyr is susceptible to both direct and indirect photolysis reactions in water. The results also show that imazethapyr photolysis in paddy water will be affected by turbidity because of its impact on the availability of sunlight to drive direct and indirect photolysis reactions.