Derivatization and Detection of FAMEs in Ancient North American Soapstone Artifacts

Abstract

Prior to the production of pottery 3000 years ago, humans would often carve large bowls out of rock, usually soapstone. Samples of such an artifact from the Thrash site, a Late Archaic period (3,000-1000B.P,) site in Pike Country, Alabama, have been subjected to a three step process for identifying fatty acids, the primary substance of foodstuffs. We used gas chromatography/mass spectroscopy (GC/MS) to analyze samples from the artifact along with samples of natural soapstone. The presence of different fatty acids can provide information about prehistoric dietary habits, whether from fish, mammals and/or plants. For the analysis, however, the fatty acids must be converted (derivatized) to fatty acid methyl esters (FAMEs). We used a method that converts triacylglycerides into FAMES in a one step process. These fatty acids will be correlated to a range of plants and animals that came into an extended period of contact with the artifact.