MCI Project Summaries 2008 - Smithsonian Institution

objects. Concern about this problem has come to a head since passage of the Federal Native
American Graves Protection and Repatriation Act (NAGPRA) in 1991, which dictates that
certain classes of Native American objects must be given back to tribal communities. Repatriated
objects may be held in a museum, but they are just as likely to be used in ceremonies, worn as
clothing, stored in private homes, buried, or destroyed by the recipients. It is incumbent upon
museums to determine whether these artifacts are contaminated, and identify the pesticide(s) and
amount present so that any health risk to the recipient Native communities can be assessed. In
the absence of archival documentation of the pesticide treatment history for most objects,
analytical detection methods are necessary. Analysis of the air surrounding artifacts, either in an
enclosed environment such as a plastic bag or the larger environment of a storeroom, offers a
noninvasive, non-destructive method for detecting these substances on culturally sensitive or
fragile material.
The substrates would be made of an absorbent phase that contains SERS-active
nanoparticles. In theory, the substrate could be placed in the vicinity of objects contaminated
with volatile organic pesticides, and pesticide vapors emanating from the object(s) will be
absorbed into the SERS substrate. After a given amount of time, the exposed substrate can be
removed and transported to a Raman spectrometer for analysis. With the advent of truly portable
Raman spectrometers, some of which weigh as little as six pounds. it is possible that the analysis
ultimately could be done on site, for example in collections storage areas. The effectiveness of
the SERS substrates as vapors sensors will be assessed through comparison with other analytical
techniques including gas-chromatography (using solid phase microextraction (SPME) sampling),
gas phase Fourier-transform infrared spectroscopy (FTIR), and indirect measurement techniques
including evaluation of corrosion on exposed metal surfaces. Chemical compounds to be
evaluated include volatile organic pesticides, acetic acid, nitric acid, and phthalate plasticizers.
All are compounds that would be expected to occur in storage areas of Smithsonian Institution
museums. Additional analysis that can be carried out at MCI by existing staff includes X-ray
diffractometry, scanning electron microscopy, X-ray fluorescence spectrometry and optical
microscopy.
87