Material degradomics: on the smell of old books.

We successfully transferred and applied -omics concepts to the study of material degradation, in particular historic paper. The main volatile degradation products of paper, constituting the particular "smell of old books", were determined using headspace analysis after a 24 h predegradation procedure. Using supervised and unsupervised methods of multivariate data analysis, we were able to quantitatively correlate volatile degradation products with properties important for the preservation of historic paper: rosin, lignin and carbonyl group content, degree of polymerization of cellulose, and paper acidity. On the basis of volatile degradic footprinting, we identified degradation markers for rosin and lignin in paper and investigated their effect on degradation. Apart from the known volatile paper degradation products acetic acid and furfural, we also put forward a number of other compounds of potential interest, most notably lipid peroxidation products. The nondestructive approach can be used for rapid identification of degraded historic objects on the basis of the volatile degradation products emitted by degrading paper.