STUDY OF BINDING MEDIA IN WORKS-OF-ART BY GAS-CHROMATOGRAPHIC ANALYSIS OF AMINO-ACIDS AND FATTY-ACIDS DERIVATIZED WITH ETHYL CHLOROFORMATE

The aim of this work is to identify proteinaceous and oil binding medi a used in paintings from art collections in the Region of Valencia (Sp ain). This information is extremely useful for conservation and restor ation work. The proposed procedure involves protein and glyceride hydr olysis from sub-milligram samples by treatment with hydrochloric acid, followed by neutralization, partition with chloroform and derivatizat ion with ethyl chloroformate (ECF) of both the aqueous and the organic phases. The ECF derivatives of amino acids and azelaic, myristic, pal mitic and stearic acids are separated by capillary gas chromatography. Amino acids are mainly found in the aqueous phase and long chain fatt y acids in the organic phase. The distribution of azelaic acid was app roximately similar in the two phases. Amino acid and fatty acid ratios found proved extremely useful for identifying the binding media in th e paintings analysed. (C) 1997 Elsevier Science B.V.