Melatonin Dosage by First-derivative Spectrophotometry

The present work aims to develop a spectrophotometric method for simultaneous estimation of melatonin and Vitamin C in combined dosage form. Absorbance of melatonin and Vitamin C were measured at the absorbance maximum (λ max) at 278 and 256 nm, respectively. The coefficient of correlation for melatonin at 278 nm and Vitamin C at 256 nm is 0.9986 and 0.9968, respectively. A linear relation between the absorbance and the melatonin concentration was found in the range 50-80 μg/ml, and a similar one (0-100 μg/ml for Vitamin C). The UV-Vis first derivative spectrophotometry method have been developed in this paper for the quantitative analysis of melatonin and Vitamin C in commercial capsules.