Gas chromatographic-mass spectrometric analysis of tannin hydrolysates from the ink of ancient manuscripts (XIth to XVIth century)

International audienceA procedure has been devised for determining the constituents of ink from ancient hand-written parchments. Some of the tannic acids and sugars resulting from acid hydrolysis of ink could be identified at the nanogram level (thus necessitating the destruction of only a small amount of ink from the manuscript) by gas chromatography-mass spectrometry of their trimethylsilyl derivatives. The presence of “ferrogallic” inks on some manuscripts was assumed from the detection of gallic acid and glucose by selection ion monitoring and capillary-column gas chromatography. The method has been applied to inks from eleven European manuscripts dating from the XIth to the XVIth century, and to various possible ink precursors (extracts from gall nuts, pods of Tara (Caesalpinia spinosa) and gum arabic)