Method development for binding media analysis in painting cross-sections by desorption electrospray ionization mass...

Area of Science:

• Analytical Chemistry
• Art Conservation Science
• Mass Spectrometry

Background:

• Art conservation requires non-destructive methods for identifying paint binding media within cross-sections.
• Stratigraphic analysis of paint layers aids in identifying and removing non-original paint.
• Current methods lack the speed and specificity needed for rapid, in-situ analysis.

Purpose of the Study:

• To develop and validate a rapid, non-destructive method for identifying paint binding media in cross-sections.
• To map the spatial distribution of binding media within layered paint samples.
• To differentiate between modern and traditional binding media using mass spectrometry.

Main Methods:

• Desorption electrospray ionization mass spectrometry (DESI-MS) was employed in ambient mode.
• Cross-sections from mock-up layered paints and a 17th-century painting were analyzed.
• DESI spray was raster scanned across layers, and data analyzed using a triple quadrupole mass analyzer.

Main Results:

• Specific ions were identified to distinguish acrylic media (e.g., OP (EO)9 surfactant, m/z 621) from lipid-based media (oleic, stearic, azelaic acids, m/z 281, 283, 187).
• DESI-MS successfully mapped binding media to specific layers in mock-up cross-sections with 100 μm spatial resolution.
• Distinct mass spectral signatures enabled differentiation between acrylic, oil, and egg tempera binding media.

Conclusions:

• DESI-MS is an effective mass spectrometry technique for analyzing intact painting cross-sections.
• The method reliably distinguishes between lipid-containing and modern synthetic binding media.
• DESI-MS successfully identified binding media in a historical painting, demonstrating its practical application in art conservation.