What is the issue with percent nitrogen analysis when analyzing collagen in archaeological bone? Christina Macie Ryder, a postdoctoral researcher at Texas A&M University, explains the main problem.
In a recent study that was published in the Journal of Archaeological Science, a team of researchers, led by Christina Ryder, a postdoctoral researcher at Texas A&M University, explored how near-infrared (NIR) spectroscopy can improve the study of collagen in archaeological bone.1,2
The first three interview segments of our conversation with Ryder touched upon why NIR spectroscopy is an ideal technique to use when studying archaeological remains, compared partial least squares regression (PLSR) and random forest (RF) modeling techniques, and explained what the best spectral region is for studying collagen-related spectral features.
Christina Ryder discusses the evolution of pre-screening methods used to evaluate collagen preservation in archaeological bone in the below interview segment, contrasting traditional destructive techniques with newer non-destructive approaches.
Researchers normally relied on percent nitrogen analysis, which involves grinding approximately five milligrams of bone and measuring nitrogen content as a proxy for collagen preservation. Although this method is effective, this method is inherently destructive and requires transporting samples to a laboratory, often involving complex permitting processes and curatorial approval. This logistical burden is compounded by the fact that sampling typically occurs before researchers can confirm whether sufficient collagen is present, risking unnecessary damage to valuable specimens.
Ryder highlights how near infrared (NIR) spectroscopy is transforming this workflow. Unlike percent nitrogen analysis, NIR is portable, non-destructive, and can be performed directly at excavation sites or within museum collections. Battery-powered devices allow researchers to analyze specimens in situ, sometimes even without removing them from storage drawers, depending on sample thickness and penetration depth. This approach significantly reduces the need for sample transport and associated administrative hurdles.
Importantly, NIR pre-screening offers substantial benefits to curators and researchers alike by ensuring that destructive sampling is only conducted on specimens with a high likelihood of yielding meaningful results. Ryder notes that this method supports more responsible stewardship of finite archaeological resources while improving research efficiency. A large-scale study involving over 800 specimens demonstrated an approximately 93% success rate in identifying suitable samples for radiocarbon dating and paleoproteomic analysis, underscoring the reliability and impact of non-destructive spectroscopic screening.
