In the mid-1920s, a group of medieval Islamic silks (known as the “Buyid Silks”) dating between the eighth and twelfth centuries was excavated at BiBi Shahrbanoo, a shrine south of Tehran. Additional textile pieces surfaced in the 1940s, but doubts arose regarding the authenticity of some of the fragments and lead to discussions among curators, art historians, and dealers. Accurate dating of many Buyid fragments has not yet been ascertained. We have developed several new techniques for dating proteinaceous historical artifacts using modern separation/mass spectrometry and proteomics techniques. By using these techniques we have identified several biomarkers of natural aging in proteinaceous cultural heritage objects which are based on racemization and deamidation of amino acids in proteinaceous specimens. Our dating technique uses capillary electrophoresis mass spectrometry (CE-MS) to measure D/L of aspartic acid (Asp), and a proteomics technique to measure the deamidation rate of asparagine in silk proteins. To test the authenticity of the BiBi Shahrbanoo silk, we have analyzed a dozen samples from the Textile Museum in Washington, DC, and compared the change in racemization and deamidation in both authentic and unknown silk samples. In addition, we have compared these data with the rate of racemization and deamidation in artificially aged silk proteins. Modern silk samples were aged using pH, heat, and radiation. Thirteen silk fragments were HCl digested and analyzed by chiral CE-MS and the D/L Asp was measured. Moreover, for the deamidation study, these samples were enzymatically digested and analyzed by proteomics techniques. Two of the fragments that were purchased originally by the museum were among the samples. One of these fragments was carbon dated and was used as the control. Our results were consistent with the skepticism regarding the authenticity of nine fragments, indicating the possibility that they were artificially aged to look older. This presentation will discuss the results of this investigation.<br/>Ackmowledgemnts: We wish to thank Dr. Sumru Krody and Esther Methe of the Textile MUseum, Washington DC, for providing the silk samples.  This material is based upon work supported by the National Science Foundation under Grant Number CHE 1440849.

Identification of forgery in proteinaceous cultural heritage objects by comparing the biomarkers of natural and artificial aging

251st National Meeting (2016)

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