The contribution of gas chromatography to the resynthesis of the post-Byzantine artist’s technique

Abstract

Gas chromatographic analysis of ethyl chloroformate derivatives of samples taken from the paint layers of post-Byzantine panel paintings permitted the successful characterisation of the different binding media used in them. This paper describes an analytical study of various post-Byzantine binding media such as egg yolk and egg/oil emulsion, using gas chromatography. The characterisation of these icons’ binding media is an important task, as it contributes to our understanding of and the reconstruction of the post-Byzantine artists’ palette. It also enables us to investigate the validity of our assumptions about the influences of Venetian style on Greek icon painting techniques from the sixteenth to the early nineteenth century, which up to now have been based on information in artists’ handbooks. The methodology involves two experimental steps: (1) hydrolysis of the proteins and triglycerides in the binding media to obtain free amino acids and fatty acids, and (2) the formation of ethyl chloroformate derivatives via derivatization with ethyl chloroformate (ECF). This methodology is of considerable interest, since it permits the identifcation of the nature of the proteinaceous binders used in these works through the simultaneous derivatization and determination of amino acids and fatty acids. Advantages of this methodology include the small quantity of sample required and the minimum preparation time involved. The proteinaceous media can be determined based on the ratios of seven stable amino acids, while the type of emulsions and drying oils used can be determined from the fatty acid ratio.