LAUSR

Abstract Photodegradation of tamoxifen (TAM) is investigated by chemometric analysis of the multiset data obtained by LC-DAD/MS and UV spectrophotometry. A hydroalcoholic solution of TAM was submitted to photodegradation by means of a dedicate irradiation cabinet able to simulate natural irradiation sources. The irradiance conditions were stressed by increasing the irradiation power to produce a rapid photodegradation of TAM. Drug photodegradation was monitored through UV spectrophotometry and the obtained photoproducts were investigated in detail by DAD/MS liquid chromatography. Data collected from the combination of both instrumental techniques were fused and processed jointly using the Multivariate Curve Resolution–Alternating Least Squares (MCR-ALS) method. A total number of five compounds were identified during the drug photodegradation and their kinetic evolution was described. The process included the isomerization of TAM to its (E)-form and the subsequent cyclization of these both compounds to give two phenanthrene derivatives. A photooxygenation process can also occur, giving a benzophenone derivative photoproduct as a result thereof. The multivariate resolution method proposed in this work allowed the resolution of this complex multicomponent system by the direct analysis of the experimental data.