Mapping organic lake pigments in works of art with Mass Spectrometry Imaging

From the moment an artist completes a painting spontaneous and unwanted chemical transformations start to take place, leading to the gradual loss of brightness and intensity of the original color. Therefore, to gain more knowledge on the artist’s technique a full characterization of all materials used in the artwork is required. For this aim, impressive advances have been made regarding the identification of inorganic pigments and their associated reaction mechanisms by non-invasive spectral imaging of the painting, and synchrotron radiation-based techniques applied to minuscule paint fragments. However, the non-invasive detection of organic pigments remains challenging and becomes especially difficult when the original pigment has degraded or is present at a very low concentration. While traditional separation chromatographic techniques have contributed significantly to the identification of organic pigments, the necessary sample preparation implies the loss of the spatial distribution of the pigment within the paint layers. Hence, this NICAS Small Grant aims to exploit the novel application of Matrix-Assisted Laser Desorption Ionization – Mass Spectrometry Imaging (MALDI-MSI) to visualize the spatial distribution of organic lake pigments and their degradation fragments within the paint sample without extraction, purification and separation steps.