Photostability determination of arbutin, a vegetable whitening agent

The target of this research was to evaluate the photostability at various pH values of 1.20 x 10(-4) M aqueous solution of arbutin (lambda max = 267 nm; epsilon = 7500 M-1.cm-1). This photodegradation appeared to follow first-order kinetics whatever the pH. The degradation rate constant was calculated to be 5.5 x 10(-4), 7.0 x 10(-4) and 24.1 x 10(-4) min-1, respectively at pH 5, 7 and 9.