ART CONSERVATION: USE OF CHROMATOGRAPHY IN
S.L. Vallance, in Encyclopedia of Separation Science, 2000
Ion exchange chromatography (IEX) separates proteins with differences in surface charge to give high-resolution separation with high sample loading capacity. The separation is based on the reversible interaction between a charged protein and an oppositely charged chromatography resin.
Ion Exchange Chromatography
Ion exchange chromatography was first used for the analysis of samples from works of art in 1969 when the successful analysis of antique and modern art specimens was reported. The eluted amino acids were detected by optical density with ninhydrin, then the percentage amino acid composition was calculated for each sample. Samples of gelatine, casein, glair, tempera and even animal horn were characterized using this method.
The use of ion exchange chromatography in this particular area is problematic: the method of sample preparation is both lengthy and complex, pH gradients are difficult to control precisely and the required sample size of paint is relatively large when put into the context of a specimen to be removed from a valuable work of art. Furthermore, museums and galleries are notoriously short of both money and space, thus specific single-purpose equipment is deemed unaffordable by many institutions.