Applications of mass spectrometry in cultural heritage: identification of ligands employed for mordant gilding

Three different samples of gilding from wall paintings, from the Palazzo della Ragione in Padua, have been investigated by GC/MS analysis of their basic hydrolysis products obtained using trimethyl(alpha,alpha,alpha-trifluoro-m-tolyl)ammonium hydroxide (TMTFTH). The method employed allowed the identification of the mordant used for the paints, and consequently to distinguish Menabuoi's original painting from the others produced by extensive restorations. This was achieved by characterizing, among the hydrolysis products, molecular species characteristic of natural resins, siccative oils and waxes.