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Multivariate curve resolution-alternating least squares (MCR-ALS) has been applied to data collected from UV spectrophotometric analysis of melatonin samples exposed to light with varying irradiance power. MCR-ALS was able to explain the degradation kinetics of this drug, deducing the pure spectra and concentration changes of the different species present throughout the entire process. Possible rotational ambiguities associated with MCR solutions were investigated and their extent was evaluated. The extent of the rotation ambiguity was estimated from the band boundaries of feasible solutions calculated using the MCR-BANDS procedure. The use of a non-linear fitting routine allowed improving kinetic information and provided a method of evaluation of the rate constants of the degradation process. The degradation pathway was found to follow a first-order reaction model, in which melatonin underwent photo-oxidation of the indole ring to give a formylamine group. Kinetics of the reaction was shown to be dependent on irradiation conditions, with an increase of the rate constants when light power also increased. Copyright © 2011 John Wiley & Sons, Ltd.
Department of Pharmaceutical Sciences, University of Calabria, Via P. Bucci, 87036 Rende, Italy.
This article was published in the following journal.
Name: Drug testing and analysis
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A melatonin receptor subtype primarily found expressed in the BRAIN and RETINA.
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Pharmacy is the science and technique of preparing as well as dispensing drugs and medicines. It is a health profession that links health sciences with chemical sciences and aims to ensure the safe and effective use of pharmaceutical drugs. The scope of...