GAS-CHROMATOGRAPHY - MASS-SPECTROMETRY IDENTIFICATION OF COLLAGEN BREAKDOWN PRODUCTS IN NATURALLY AND ARTIFICIALLY AGED LEATHERS

The purpose of this study is the detection and identification, using c ombined gas chromatography and mass spectrometry, of breakdown product s which appear during leather collagen degradation. Experiments were p erformed on naturally and artificially aged leathers. All gas chromato grams are similar, with high amounts of the classical amino acids toge ther with a great number of others at low concentration of which sever al were identified as: alpha-aminobutyric acid, beta-alanine, pyroglut amic acid, allo-isoleucine, gamma-aminobutyric acid (GABA), dehydropro line (dPRO), two isomers of hydroxyproline (cis-3-HYP and cis-4-HYP), 6-aminohexanoic acid, ornithine and alpha-aminoadipic acid (AAD). To e valuate how much artificial aging affects the release of the breakdown products, and to compare it to natural aging, semiquantitative and co mparative analysis were performed on four ''new'' amino acids. We calc ulated and studied the evolution of the following peaks area ratios: G ABA/dPRO, cis-4-HYP/trans-4-HYP, dPRO/PRO and AAD/dPRO. Our results co nfirm the hypothesis that amino acids are first transformed into break down products in the form of new amino acids, which are then transform ed into other breakdown products or amino acids.