The use of FTIR microspectroscopy and chemometric analysis in the discrimination between Egyptian ancient bones: A case study

Bones are mostly composed of analogous volume fractions of collagen as organic material and apatite as minerals. After burial, bones undergo several complicated depositional variations in the calcified tissues (diagenesis). Since bones are hard tissues, they can confer many crucial and vital data. Fourier transform infrared (FTIR) microspectroscopy is a powerful molecular spectroscopic tool that can trace the molecular changes with high spatial resolution. The current research is a case study that is aimed at probing the diagenetic changes across different depth sections of two bone shafts by transmission FTIR imaging and chemometric analysis. Amide I, carbonyl, carbonate, and phosphate bands as well as the indices of amide I/phosphate and V3-carbonate/phosphate ratios were used to construct chemical images of the bone shafts belonging to two ancient Egyptian dynasties, namely, Roman Greek (RG) period and late period (LP). Chemical images showed different chemical distribution in the external part of the two bone shafts. Principal component analysis efficiently discriminated between the investigated bones and between various depth regions from the same bone section.