Pigment identification in artwork using graphite furnace atomic absorption spectrometry
D M Goltz1, J Coombs, C Marion
1Department of Chemistry, Centre for Scientific and Curatorial Analysis of Painting Elements (C-SCAPE), University of Winnipeg, 515 Portage Avenue, Winnipeg, Man., Canada R3B 2E9.
Talanta
|October 31, 2008
Summary
A novel cotton swab technique allows for invisible pigment sampling from painted surfaces for metal identification. This method, combined with graphite furnace atomic absorption spectrometry and Raman spectroscopy, enables accurate analysis of inorganic pigments in art.
Area of Science:
- Art Conservation Science
- Analytical Chemistry
- Materials Science
Background:
- Inorganic pigments are crucial components of historical and contemporary paints.
- Accurate identification of pigment composition is essential for art conservation and authentication.
- Traditional sampling methods can be destructive, posing risks to valuable artworks.
Purpose of the Study:
- To develop and validate a minimally invasive sampling technique for inorganic pigment analysis.
- To assess the efficacy of graphite furnace atomic absorption spectrometry (GFAAS) and Raman spectroscopy for pigment identification.
- To demonstrate the combined utility of GFAAS and Raman spectroscopy for comprehensive pigment characterization.
Main Methods:
- A non-destructive cotton swab sampling technique was employed to collect minute pigment quantities (1-2 µg).
- Pigment metals were extracted using nitric acid (HNO3) for analysis via graphite furnace atomic absorption spectrometry (GFAAS).
- Raman spectroscopy was utilized to provide complementary structural and chemical information.
Main Results:
- The cotton swab sampling method proved effective, yielding invisible removal of pigment from painted surfaces.
- GFAAS successfully identified various metals in inorganic pigments, with good reproducibility (approx. 13% for Cadmium Red).
- The combination of GFAAS and Raman spectroscopy enabled definitive identification of pigments, such as distinguishing copper presence from specific copper phthalocyanine green.
Conclusions:
- The developed cotton swab sampling technique is a viable, minimally invasive method for inorganic pigment analysis.
- The synergistic application of GFAAS and Raman spectroscopy offers a powerful approach for accurate pigment identification in artworks.
- This integrated analytical strategy supports art conservation, authentication, and provenance research.
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