CHARACTERIZATION OF MEDIEVAL PROTEINACEOUS PAINTING MEDIA USING GAS-CHROMATOGRAPHY AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Proteinaceous organic materials used as ancient painting media were in vestigated by capillary gas chromatography (GC) and capillary gas chro matography - mass spectrometry (GC/MS). Medieval wall paintings made b y the tempera technique were considered and their binding media were s tudied by the characterization of their main chemical components. The basic methodology is based on the determination of amino acids in samp les of paint layers after hydrolysis and derivatization and on the com parison with reference proteinaceous materials. Multivariate chemometr ic techniques were used to facilitate the recognition of the protein s ource from chromatographic data. To characterize the binders further, a method was developed for the determination of fatty acids, present a s minor components, by GC/MS. The use of fused-silica capillary column s coated with selected stationary phases allowed the separation of ami no acid and fatty acid derivatives in a single analytical run.