抄録
Isouron (1), one of the urea herbicides was determined colorimetrically by application to diazo coupling with Tsuda reagent. 3-Amino-5-tert-butylisoxazole (2) obtainable by the hydrolysis of 1 was diazotized with HNO2 and the diazonium salt was easily coupled with Tsuda reagent. The diazonium salt was unstable at room temperature different from aniline but stable in cooled water. The calibration curve was linear in a range of 3-15 μg/ml of the standard solution of 1, the coefficient of variation of 0.3-1.3%. 5-Amino-3-tert-butylisoxazole (6) produced by the hydrolysis of the isomer 1-(3-tert-butylisoxazol-5-yl)-3, 3-dimethylurea (5) was not diazotized in the present condition. The effect of major impurity (5) on the determination was removable.
