Modern art materials introduced since the end of XIX century include a large number of formulations of synthetic polymers and pigments, whose degradation processes and best preservation conditions are a major issue in heritage science. Analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) is widely used for the characterisation of polymeric materials and organic pigments, however the interpretation of the pyrograms obtained from samples containing different analytes is not straightforward. To improve our understanding on how these materials behave in complex matrices, we used evolved gas analysis coupled with mass spectrometry (EGA-MS) and multi shot Py-GC/MS to highlight and analyse the different fractions in a sample from a pop-art made of painted polyurethane (PU) foam. The study represents a proof of concept to evaluate EGA-MS potential in studying composite modern art materials in combination with multi-shot pyrolysis. The aim of the investigation was establishing the composition of the PU formulation, the paint binder and the pigments, thereby contributing to planning the stabilisation and conservation of the object. The polymers and the class of synthetic organic pigments present in the paint were assessed by determining their specific pyrolysis products and through comparisons with data in the literature. EGA-MS analysis provided both thermal and chemical information in one analytical run, so that we could select four temperatures for use in multi-shot Py-GC/MS analysis and thus to selectively study the different fractions evolved at different temperatures. Information on the various components of the mixture was obtained, including additives and organic pigments, separating them on the basis of their different thermal degradation temperatures. The multianalytical approach included also non-destructive ATR-FTIR and enabled us to characterize in detail different synthetic materials: polyether-based polyurethane produced by the polyaddition of 2,6-diisocyanate toluene, hexamethylene diisocyanate and polypropylene glycol, vinyl paint, and a mixture of β-naphthol and mono-azo as pigments. HPLC-DAD and HPLC-ESI-MS analyses confirmed the pigments, and provided a positive identification of two β-naphthols (PO5 and PR1) and two monoazo pigments (PY1 and PY3).

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Eosin (Acid Red 87, C.I. 45380) is one of the most brilliant and challenging early synthetic dyes. In this study, an analytical approach based on high‐performance liquid chromatography coupled with diode array and fluorescence detector and high resolution mass spectrometry was developed for testing different analytical columns and acids in the mobile phase. The ultra‐sensitive approach, based on a chromatographic separation on a solid core and a porous shell Poroshell 120 EC‐C18, allowed us to detect and characterize eosin and its synthesis by‐products, such as the debrominated and methyl ester forms of eosin, in trace levels (the limit of detection for eosin is 0.13 ppb). The resulting miscellaneous composition of the eosin standard highlights the importance to determine the exact composition of the starting material to deal with, in order to avoid misinterpretations in aged or degraded samples. Finally, the successful identification of eosin in few grains (approximatively 20 × 40 μm wide) of a faded Van Gogh's painting proved the strengths of our approach.