The Limitations of Near-Infrared Collagen Prediction

A recently published study in the Journal of Archaeological Science discusses how near-infrared (NIR) spectroscopy can be a rapid, fully non-destructive method for assessing collagen preservation in archaeological bone.^1,2 Collagen is critical for analyses like radiocarbon dating, but diagenesis can degrade it unpredictably.¹ Unlike traditional destructive methods or limited spectroscopic alternatives, NIR penetrates below the bone surface, indicating that this technique could be more widely adopted in bioarchaeology.¹

Christina Ryder, who is a postdoctoral researcher at Texas A&M University, was the lead author of the paper based off of this study, and she recently sat down with Spectroscopy to discuss the study’s findings and how NIR spectroscopy could change bioarchaeology in the future.

In this final interview clip from our conversation, Ryder highlighted the key challenges and ongoing efforts to improve NIR spectroscopy for collagen pre-screening in archaeological materials.

What are the limitations of near-infrared (NIR) spectroscopy in screening archaeological materials?

A primary limitation discussed in the video is the restricted penetration depth of NIR light, particularly in dense materials like cortical bone from large specimens such as mammoths and mastodons. This limitation is further complicated by diagenetic processes, where mineralization alters bone surfaces and can obscure the condition of underlying collagen. To address this, Ryder collected spectra from multiple pointson a sample and focuses on exposed cross sections to better approximate internal composition.

Ryder also emphasizes in the video clip that there is a need to better understand how NIR penetration varies across different biological materials, including bone, dentin, antler, and ivory. This work aims to refine the method’s reliability and broaden its applicability. Beyond technical challenges, she identifies two major practical barriers: the high cost of NIR instrumentation and the difficulties in transferring predictive models between devices. To overcome these issues, Ryder is collaborating with others to develop more universally transferable models.

Importantly, she is also working with lower-cost, handheld spectrometers that integrate with smartphones, making NIR spectroscopy more accessible for fieldwork and use in museum collections.

References

1. Ryder, C.; Celis, G.; Devièse, T. et al. Refining Near-infrared Spectroscopy for Collagen Quantification: A New Predictive Model for Archaeological Bone. J. Arch. Sci. 2026, 185, 106448. DOI: 10.1016/j.jas.2025.106448
2. Wetzel, W.; Spectroscopy Staff. Collagen Preservation in Archaeological Bone Using NIR Spectroscopy. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/collagen-preservation-in-archaeological-bone-using-nir-spectroscopy (accessed 2026-03-31).