GAS-CHROMATOGRAPHIC ANALYSIS OF AMINO-ACIDS AS ETHYL CHLOROFORMATE DERIVATIVES .2. EFFECTS OF PIGMENTS AND ACCELERATED AGING ON THE IDENTIFICATION OF PROTEINACEOUS BINDING MEDIA

Proteinaceous binding media present in paintings can be identified by gas chromatographic analysis of the ethyl chloroformate derivatives of amino acids. The effects of pigments on the amino acid composition da ta of hydrolyzed gelatin that were obtained by this method were studie d. The method was also used to analyze glue and egg tempera paint film s that were exposed to heat and light in order to accelerate the aging of the paints. Pigments and accelerated aging were found to affect th e concentrations of all amino acids, although the concentrations of al kyl and imino-substituted amino acids were affected to a much smaller degree than others. Samples of grounds and paints that were removed ho m a number of paintings and painted objects were analyzed by this meth od. The proteins present in the samples were identified from the amino acid molar percentages by correlation to published amino acid composi tion data.