Thermogravimetric analysis and Py-GC/MS for discrimination of leather from different animal species and tanning processes

Abstract

The analysis of thermal behaviour of materials has been commonly used for their characterisation and identification. This work aims to analyse the thermal decomposition and the pyrolytic products from leather of different animal species and tanning processes in order to discriminate them. The animal species studied were bovine hide, horsehide, pigskin, sheepskin and goatskin. Three different tanning agents were selected in this study (chromium salts, glutaraldehyde and vegetable tannins) at three different stages of the tanning process (pickled, tanned and crust leather). The thermal decomposition of all samples was studied by means of thermogravimetric analysis while the pyrolytic products were analysed using a pyrolyser connected online to a Gas Chromatograph-Mass Spectrometer (Py-GC/MS). Significant differences in the results obtained by both techniques can be observed depending on the treatments and animal species. Multivariate statistical analysis (MVA) based on principal component analysis confirm differences observed between leather samples, thus allowing the discrimination of both the animal origin and the tanning treatment.