Influence of pH on the photodegradation kinetics under UV light of climbazole solutions

Abstract

The objective of this research was to study the effect of pH on the photodegradation kinetics of 15.8 μg.ml-1 aqueous solutions of climbazole. A high-performance liquid chromatographic method for the quantification of climbazole after irradiation of aqueous solutions was carried out, using a RP-18 column with a acetonitrile - 0.05 M sodium perchlorate mobile phase. The detector was set at a wavelength of 220 nm. Calibration curve showed linear response in the interval 5 to 25 μg.ml-1. Photodegradation appeared to follow first-order kinetics and was found pH-dependent. The degradation rate constant was calcu- lated to be 10.5 〈 10-3, 9.9 〈 10-3 and 16.5 〈 10-3 min-1, respectively at pH 5, 7 and 9.