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A collection of 76 synthetic organic pigments was analysed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The purpose of this work was to expand the knowledge on synthetic pigments and to assess characteristic pyrolysis products that could help in the identification of these pigments in paint samples. We analysed several classes of synthetic pigments not previously reported as being analysed by this technique: some metal complexes, β-naphthol pigment lakes, BONA pigment lakes, disazopyrazolone, triarylcarbonium, dioxazine, anthraquinone, indanthrone, isoindoline and thioindigo classes. We also report for the first time the Py-GC/MS analysis of a number of naphthol AS, benzimidazolone, phthalocyanine and perylene pigments and other miscellaneous pigments including pigments with unpublished chemical structure. We successfully used the Py-GC/MS technique for the analysis of paints by artists Clyfford Still and Jackson Pollock to identify the synthetic organic pigments and the binding media.

Lipid binders have traditionally been determined in paintings by using gas chromatography/mass spectrometry (GC/MS) to identify the characteristic profiles and ratios of fatty acids . However, the presence of mixtures in contemporary and modern oil paints makes the GC/MS determination of fatty acids insufficient to fully characterize the lipid binding media. In this study we prove that triacylglycerol (TAG) profiling by high-performance liquid chromatography with high-resolution tandem mass spectrometry, using ESI in positive and negative ionization modes is highly effective. We exploited this analytical approach to study the curing and degradation processes undergone by six plant oils used in the formulation of media in modern paints, using both natural and artificial ageing experiments. We believe that is the first time that a negative ionization mode has been applied for this purpose and that a survey with HPLC-ESI-Q-ToF has been carried out to study the ageing kinetics of plant oils. TAG profiling enabled us to study the evolution over time of the constituents of modern oils, with respect to curing and ageing. The data analyzed in this study demonstrate that our approach is efficient to study the oxidation of TAGs during ageing. The data also improve current knowledge on the properties of vegetable oils, which could lead to the development of new paint materials and conservation treatments for modern and contemporary works of art.

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