Pyrolysis gas chromatography-mass spectrometry of triarylmethane dyes

Triarylmethane (TAM) dyes are commonly used in modern inks and paints and are of large interest in different fields of application such as cultural heritage, forensic sciences, dying industry. Here, a systematic pyrolysis-gas chromatography-mass spectrometry study of eight commonly used green, blue and violet triarylmethane dyes (Basic Violet 1, Basic Violet 3, Basic Violet 14, Basic Blue 11, Acid Green 5, Acid Blue 9, Acid Blue 22 and Basic Green 1) is presented. Pyrolysis temperatures ranging from 300 °C up to 800 °C were applied in order to study the pyrolysis products generated at each temperature. Low temperatures (300 and 400 °C) were not sufficient to distinguish between the different TAMs, whereas at 550 °C, a common temperature in paint analysis, a series of specific compounds useful in differentiation is formed, although at 700 °C a larger number of markers is generated. Py-GC-MS of two blue felt-tip pen inks used by modern artists was also carried out in order to verify the possibility to detect low amounts of TAMs in complex matrices. Although not all the pyrolysis products of the reference TAMs could be detected, efficient identification of the dyes could be accomplished thanks to the presence of specific markers

A multianalytical study of archeological faience from Vesuvian area as a valid tool to investigate provenance and technological features

The investigation was aimed at defining the compositional and structural characteristics of a group of monochrome blue faiences recovered in Pompeii to assess provenance on the basis of their technological features. Different complementary analytical techniques were used: Scanning Electron Microscopy (SEM) to investigate the morphological aspects of the samples and in particular of the interfaces, micro-Raman Spectroscopy and XRPD to identify crystalline phases and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to assess the elemental composition due to its sensitivity to a wide range of elements and the adequate lateral resolution. Statistical data treatment of the elemental concentrations of both the ceramic bodies and the glazes allowed us to classify the objects into compositional groups and to verify the previously established archaeological hypothesis suggesting an Egyptian provenance for faience of Pompeii

San Francesco d’Assisi (Apulia, South Italy): Study of a manipulated 13th century panel painting by complementary diagnostic techniques

The panel painting ‘‘S. Francesco d’Assisi’’ (Museo diocesano ‘‘Mons. A. Marena’’, Bitonto, Italy), executed around the half of the 13th century and manipulated at least two times in the following centuries, was studied by various complementary analytical techniques in order to characterise the original medieval painting technique and the subsequent editions. Optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), micro-Raman spectroscopy and pyrolysisegas chromatographyemass spectrometry (Py-GC/MS) were applied on various samples taken from significant parts of the painting. Several in situ micro-Raman analyses were also performed. The results obtained confirm that the painting belongs to the 13th century Italian painting tradition. Furthermore, combination of various analytical techniques revealed that the 13th century original background, which now appears dark grey, was realised by applying a tin foil covered by a mecca layer composed of siccative oil and heated Pinaceae resin. Thus, originally the background should have had a gold-like appearance. The most important manipulation of the painting of S. Francesco probably dates back to the 16th century but shows a quite traditional technique