Analytical Studies on Isoxazoles. IV. : Fluorometric Determination of Isouron

抄録

A fluorometric method for the determination of isouron (1) was established by modifying Dombrowski's method. Isouron was hydrolyzed to 3-amino-5-tert-butylisoxazole (2) followed by diazo coupling with 2, 6-diaminopyridine (DAP), and the resulting azo derivative (3) was oxidized to a fluorescent triazole (4). A simple nitrosation method was developed in order to overcome the interference by the strongly fluorescent reagent DAP. The oxidation yield of 3 to 4 was improved by employing the neutral condition. A linear relationship between the fluorescence intensity and isouron concentration was obtained in the range of 0.1-0.4 μg/ml. Isouron could be determined with a coefficient of variation of 2-3% (ten determinations), overall recovery of 85-90%, and quantitation limit of 40 ng/ml.