Analytical Laser Mass Spectrometry

Archaeological wine vessels

The old adage you are what you eat (and drink) is perhaps the greatest indicator of culture, status and ethnic identity. In anthropological terms this is referred to as foodways analysis. We will use resonant ionization mass spectrometry to provide direct evidence of foodways from ancient ceramic drinking vessels. By determining the presence of wine in ancient Egyptian and Nubian vessels, we hope to shed new light on the cultural dynamics between these two rival ethnic groups and how this changed across time and political power shifts.

Anthocyanins in wine have been shown to survive over time and their associated phenolic acids can be recovered by alkaline fusion for analysis. 1,2 Figure 1 shows the R2PI spectra for five phenolic acids, which we measured in our laboratory. Although they normally all absorb in the same wavelength region, they each have unique resonance wavelengths under the jet-cooling conditions of our experiment. These specific resonances allow us to selectively ionize each of these components without ionizing any other compounds. Furthermore, comparison of on- and off-resonance mass spectra firmly establishes molecular identification by optical spectroscopy in addition to mass spectrometry.

We have successfully detected these wine markers in a model experiment using modern wine absorbed in a clay vessel. We have also addressed issues of contamination during our preliminary study to exclude any cross-contamination when sampling liquid extracts by employing disposable graphite discs as a desorption substrate. The next phase of this research will focus on analyzing archaeological vessel fragments. Resonant ionization mass spectrometry is highly specific and sensitive and its application would be a first for analyzing archaeological samples.

This project is in collaboration with Prof. Stuart Smith in the department of anthropology.

Contact Mike Callahan (mcallahan@chem.ucsb.edu) for any questions or comments.

Acknowledgment:

This work is funded by the Nationa Science Foundation, Award CHE1018804

References:

(1) Singelton, V. I. (1996) in The origins and ancient history of wine, eds. McGovern, P. E., Flemming, S. J., & Katz, S. H. (Gordon and Breach, Luxembourg), pp. 67-78.

(2) Guasch-Jane, M. R., Ibern-Gomez, M., Andres-Lacueva, C., Jauregui, O., & Lamuela Raventos, R. M. (2004) Analytical Chemistry 76, 1672-1677.

 

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