Electrochemical analysis of the alterations in copper pigments using charge transfer coefficient/peak potential diagrams. Application to microsamplesof baroque wall paintings attached to polymer film electrodes

The alteration of copper pigments in art samples was studied by linear scan and cyclic voltammetry using sample-modified Elvacite 2044 film electrodes on the basis of two-dimensional diagrams of charge transfer coefficients c alculated from Tafel plots of reductive dissolution processes vs. peak pote ntial. Characteristic voltammetric peaks were obtained for pigments used in the baroque vault frescoes of the Basilica de la Virgen de los Desamparado s painted by Antonio Palomino. Results obtained by voltammetric techniques were compared with those from SEM/EDX and FT-IR analysis obtaining a good a greement and leaving to an unambiguous identification of pigments used by P alomino and their alteration products.