Evaluation of a characterization method of Egyptian human mummy balms by chemometric treatments of infrared data

Abstract

In the context where lengthy protocols are used to extract and to characterize each substance from mummification balms using techniques such as gas chromatography and mass spectrometry, this paper presents the evaluation of the efficiency of an original method to characterize mummification balms using the SIMPLISMA algorithm in infrared spectroscopy. This tool is a pure variable approach corresponding to the selection of calibration variables. This developed approach was combined with chemometric treatment (principal component analysis) to interpret the 47 Fourier Transform Infrared spectra of human mummies’ balms from Ancient Egypt. This treatment gave 6 pure spectra and their corresponding extracted concentration profiles. The first pure spectrum corresponded to residual species, and the second to the identification of polycyclic aromatic hydrocarbons, molecules which have a pyrolytic origin. The fourth pure spectrum corresponded to proteins which were characterized, and could be considered as markers of good conservation of individuals. The fifth pure spectrum characterized polysaccharides. Finally, two pure spectra showed the same natural substance, namely fat, which, on the one hand, was unaltered and, on the other hand, was degraded fatty matter. This fast, simple and non-destructive approach allowed the composition of each balm to be studied and their state of conservation/degradation to be characterized. This approach enabled the presence of proteins, polysaccharides and fatty matter or beeswax in different states of conservation/alteration in the studied balms to be characterized.