Non-invasive identification of synthetic organic pigments in contemporary art paints by visible-excited spectrofluorimetry and visible reflectance spectroscopy.

The non-destructive, in-situ identification of synthetic organic pigments employed in contemporary painting still represents a challenge. In the present study, a non-invasive analytical method based on spectrofluorimetry and visible reflectance spectroscopy was developed to this aim and applied to a considerable number of synthetic organic pigments belonging to the main chemical classes and sold by different manufacturers. In order to discriminate among them, the collected data were processed by a multivariate statistical approach, using principal component analysis (PCA). Moreover, the Kubelka-Munk correction for self-absorption of fluorescence emission was successfully applied to identify pigments in binary mixtures. This approach was finally exploited to recognise the organic pigments used by the artist in a contemporary painting.