Ageing and fading of organic pigments in art: a multi-analytical study based on mass spectrometric techniques

Organic dyes and pigments are among the most unstable and labile molecules in work of arts. The sensitivity of these compounds to light exposure can lead to drastic changes in the appearance of Ancient and Contemporary artworks. This thesis aims at investigating the fading and degradation processes, mainly due to photo-oxidation effects, of several synthetic organic pigments, poorly investigated until now. The ageing phenomena were mainly investigated by means of Liquid Chromatography coupled with Diode Array and Fluorescence Detector or high-resolution mass spectrometry (LC-DAD-FD, LC-HRMS). Nevertheless, several other techniques such as colorimetry, Infrared spectroscopy and electrochemical methods were applied for better describing the degradation phenomena. The thesis outline is as follows: state of the art, materials and methods, Nitro dyes and pigments, Monoazo pigments, β-naphthol and naphthol AS dyes and pigments, Xanthene dyes and pigments, Triarylmethine dyes and pigments, Case study of “Composizione-Superficie lunare” by Giulio Turcato, ageing of wool-degradation of the textile matrix.