This poster was presented at the American Institute for Conservation’s 37th Annual Meeting held in Los Angeles, CA, May 19-22, 2009.
An alternative sampling method was investigated using ethylenediaminetetraacetic acid (EDTA) to extract lead (Pb) directly from an object for Pb isotope analysis to source archaeological metal artifacts. In order to perform the extraction, a group of objects from the sites of Kerkenes Dağ (Turkey) and Lofkënd (Albania) was soaked in a solution of EDTA and the Pb rich solution was then analyzed using time of flight inductively coupled mass spectrometry (TOF-ICP-MS) to determine the isotopic ratios present. In the archaeological literature success has been reported using this technique for the sourcing of majolica in the American Southwest and lead and silver objects in Pakistan. The authors in these cases reported no macroscopic alteration to the artifacts after soaking in the EDTA solution. However, no study has been undertaken to determine whether the extraction technique alters the surface of the object when examined under magnification.
Preliminary work was conducted by the authors in order to determine 1) whether or not this sampling technique could effectively be used for sourcing archaeological bronzes, in addition to silver and lead artifacts, from Anatolia and Albania and 2) whether soaking archaeological metals in EDTA causes any alteration to the surface of the objects.
Initial results of the Pb isotope analysis from the Turkish material indicated that EDTA solubilizes representatively for its accurate analysis. Examination of the objects in the field after extraction showed no observable change to the surfaces up to 45x magnification. Further work still needs to be undertaken to determine what surface changes or alterations to the object may be occurring during the extraction, since it is clear that material in addition to lead is being extracted out of the metallic artifacts. Based on these initial findings, however, EDTA extraction shows some promise as an alternative method of sampling metallic artifacts to the standard sampling methods used.