Manuscript samples with iron gall inks were analysed by gas chromatography-mass spectrometry (GC-MS) and scanning electron microscopy energy dispersive X-ray microanalysis (SEM-EDX). The samples, on paper and parchment bases, showed different colour and acidic behaviour. Inorganic elements analysed by SEM-EDX showed different sulphur and iron distributions on the base. The different ration between the sulphur and the calcium was noted also. Gallic acid and sugars in the ink were tested by GC-MS. These compounds were identified by mass spectral analysis and coinjection of standard products. The results were different for light inks and dark or acidic inks. The gallic acid remains only in the dark inks, but in the light and very acidic inks, gallic acid could not be found. Sugars that come from gum arabic were present in the light inks and in those dark inks that were not very acidic. The carbonized samples retain very small amounts of sugars. -- CAL