Compositional analysis of archaeological leather and simulated leather and their degradation research based on HRMS

Leather, one of the earliest natural materials, was extensively used not only in daily attire but also in military protection in ancient times. Combined with simulated degradation experiments, high-resolution mass spectrometry (HRMS) was employed for the rapid and non-targeted detection of components in archaeological leathers, and for the systematic analysis of the chemical composition of leather samples. Comparative amino acid analysis of simulated and archaeological leather samples demonstrated that the L-hydroxyproline content and the signal intensity ratio of isoleucine and leucine to valine serve as integrated parameters for evaluating the aging status of leather. Moreover, the identification of other amino acids and tens of degraded products such as succinic acid, L-carnitine and 4-guanidinobutanoic acid deserve special attention. 4-Guanidinobutanoic acid existed in both simulated leather and archaeological artifacts. This research provides a new analytical tool for gaining significant insights into ancient leathers and their degradation status. In addition, HRMS enables the detection of early degradation signals in cultural relics, allowing conservation professionals to quantify degradation levels among different artifacts. This facilitates the prioritization of deteriorated leathers by heritage institutions.