Validation of a UV spectrophotometric method for the determination of melatonine in solid dosage forms

The aim of the work described in this paper was to provide a fast, easy, in expensive, precise, and accurate method for the determination of melatonine in solid pharmaceutical dosage forms. The developed method is based on a U V first-derivative spectrophotometric determination, which exhibits excelle nt linearity in aqueous solutions (r(2) = 0.996) for analyte concentrations of 1.5-4.5 mg/dL within a pH range of 5-9. Neither excipients present in t he formulation nor indole adulterants, such as tryptophan (up to 5%), inter fere with the assay. A study of variation parameters showed that sonication temperature was the main factor for successful determination. At temperatu res of < 45 degrees C, the sample dissolved completely, and accurate spectr ophotometric measurements were obtained. A study was conducted of all the p arameters established by the United States Pharmacopeia, 23rd Rev., to vali date an analytical method for a solid pharmaceutical form, i.e., linearity, range, accuracy, precision, and specificity. All the parameters were in ac cordance with the acceptance criteria of the Comite de Guias Oficiales de V alidacion de la Direccion General de Control de Insumos para la Salud de Me jico. In addition, robustness and content uniformity tests were performed t o substantiate the usefulness of the method.