Toward a Non-destructive and Comprehensive Chromatographic Extraction Method for Archaeological Biomarkers

Timothy J. Ward

wardtj@millsaps.edu

The analysis of organic residues from archaeological ceramics has been an active area of research for the last 50 years. Many studies focus on lipids since they are easily analyzable and one of the best-preserved organic compounds in archaeological materials such as pottery and human and animal remains. Other methods focus on the analysis of alkaloids or proteins. An ideal chemical analysis of organic components in archaeological materials would include all of these classes of compounds and be minimally or non-destructive to the sample material. However, such a comprehensive chemical characterization is often impractical due to various challenges during analysis, including solubility differences of multiple biomarkers, multi-step sample preparation procedures, limited resources, incompatible techniques for different compounds, and/or limited sample material.

Here we present advances in developing simple and reliable minimally destructive extraction and sample preparation techniques for a wide range of important biomarkers for GC-MS and HPLC-MS analysis. The organic extraction efficacy, selectivity, precision, and accuracy of well-established methods is compared against new techniques, such as conventional solvent extraction versus supercritical fluid extraction. Our previous work has shown that a highly destructive sample preparation (grinding ceramics to a fine powder prior to immersive solvent extraction) yields a significantly greater recovery for alkaloids than the less destructive method of washing the exterior of the ceramic with the solvent. Our current research considers minimally destructive methods with comparable or improved limits of detection, discusses sample contamination, environmental factors affecting analyte retention, and the heterogenous nature of the samples.