Hand-held Raman spectroscopy as a pre-screening tool for archaeological bone

Abstract

Bone collagen is the required substrate for a variety of archaeometric analyses, including radiocarbon dating, stable isotope analysis, proteomics, and ancient DNA. Sampling of bone for such analyses is, however, a destructive process, and biomolecular extraction is a time-, labor-, and capital-intensive process. As such, the ability to pre-screen bone for potential collagen level in the field (or in remote museums, storage repositories, or other deployed and austere environments) for archaeological and forensic purposes is highly desirable. Building on previous assessments of hand-held spectroscopic tools and several recent bench top Raman studies, and using a robust selection of well-characterized ancient bone samples, it is demonstrated here that rapid (30s), non-destructive assessment by means of 1064nm Raman spectroscopy can provide a field-deployable means by which to quantify bone collagen content. Specifically, it was found that the 1450cm-1 to 960cm-1 peak height ratio can provide quantitative estimates of bone collagen content with an error of ±2.8wt%, and those samples with ratios of greater than 0.1 are uniformly suitable for analysis. Hand-held Raman spectroscopic technology has therefore evolved to the point where field deployment by archaeologists and forensic scientists would be both justified and worthwhile.