Secondary ion mass spectrometry, a powerful tool for revealing ink formulations and animal skins in medieval manuscripts

Book production by medieval scriptoria has gained growing interest in recent studies. In this context, identifying ink compositions and parchment animal species from illuminated manuscripts is of great importance. Here, we introduce time-of-flight secondary ion mass spectrometry (ToF-SIMS) as a non-invasive tool to identify both inks and animal skins in manuscripts, at the same time. For this purpose, both positive and negative ion spectra in inked and non-inked areas were recorded. Chemical compositions of pigments (decoration) or black inks (text) were determined by searching for characteristic ion mass peaks. Animal skins were identified by data processing of raw ToF-SIMS spectra using principal component analysis (PCA). In illuminated manuscripts from the fifteenth to sixteenth century, malachite (green), azurite (blue), cinnabar (red) inorganic pigments, as well as iron-gall black ink, were identified. Carbon black and indigo (blue) organic pigments were also identified. Animal skins were identified in modern parchments of known animal species by a two-step PCA procedure. We believe the proposed method will find extensive application in material studies of medieval manuscripts, as it is non-invasive, highly sensitive and able to identify both inks and animal skins at the same time, even from traces of pigments and tiny scanned areas.In-house PCA algorithm requires python. ToF-SIMS raw data require SurfaceLab software. ATR-FTIR raw data (.0) can be read with free-licence software (Fityk). XRD diffractograms are directly exported in .txt from .xyz files. Funding provided by: Namur Institute of Structured Matter, University of NamurCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100023393Award Number:Analytical and data processing methods can be found in the associated article