Author(s): Florentin TACHE, Florentin TACHE
This paper is proposing an algorithm for demonstrating the spec ificity of the analytical method for an analyte of interest against its degradation product by applying physical ( thermal degradation and photolysis) and chemical (photolytic-hydrolysis, acidic- and alkaline- hydrolysis and ac idic-, neutral- and alkaline-oxidation) stress conditions. The authors define specific c onditions for testing capacity of the analytical method to dis tinguish between the analyte and its by-products resulting in different environmental condit ions. As an effective example, it is used the case of Metformin hydro chloride HPLC assay method. It is shown that by photolysis with white light or UV radiation the Metformin recov ery is 99.98%. By thermal degradation it can be observed a moderate difference in between mild and high tempera ture application (99.98% in the first case and 86.00% in the second case, respectively) . Photolytic-hydrolysis induce s a slightly difference depending on the wavelength (recovery of 99.98% for white light and 99.90% for UV radiation , respectively). In turn, p H dependent hydrolysis is inducing large differences (99.93% recovery in acidic range and 89.52% in the alkaline range, respectively). Oxidation of Metformin is also conducting to significant differences in a ccordance with the pH (99.90% recovery in the acidic range, 87.98% in the ne utral range and 71.09% in the alkaline r ange respe ctively).