Non-destructive chemical analysis of artificially degraded hafting adhesives with DHS-GC×GC-TOFMS

Adhesives play a crucial role in human culture since prehistory. One known example of adhesive usage in prehistory is to attach a handle to a stone tool, a process called hafting. Transforming a simple stone tool into powerful equipment such as knives. Nonetheless, archaeological evidence of hafting adhesives is rare. The handles were made from perishable organic materials, and if surviving adhesives are present on the stone tools, they are severely degraded. Chemical analysis of those adhesives traces is pivotal for our understanding of glue use. Nevertheless, highly deformed and precious sample pose chemical challenges. Preferable, non-destructive and highly sensitive instruments are used. Spectroscopy and microscopy instrumentations are mostly employed due to their ease of operation and non-destructive nature. However, the chemical data obtained from those techniques is often limited. Gas chromatography – mass spectrometer (GC-MS), on the other hand, provides the most selective data but is destructive towards the adhesives. Head space analysis with GC-MS is a non-destructive technique which provides accurate data. Unfortunately, it is hardly used in hafting adhesive chemical analysis. In this study, we investigate dynamic headspace sampling coupled to two-dimensional comprehensive GC - time-of-flight MS (GC×GC-TOFMS). An untargeted data analysis approach is investigated for the identification abilities of this method. For this a database composed of fresh adhesives is made. Subsequently, the sampling of larger, degraded stone tools is explored with an in-house made DHS sampling system and tested on UV light degraded experimental stone tools.