Chromatografia w badaniu książki zabytkowej

Paper is a basic writing material that has not been so far supplanted by the consecutive technical and technological inventions. During the centuries of paper-making, systematic changes took place, the aims of which were: improvement of paper’s quality, lowering the price and increase in the production. The present-day process of paper-making hardly resembles a few hundred years old historical production process of handmade paper. Unfortunately, as it turns out, the quality of contemporary paper has also been compromised in comparison to durable work of the old paper-making masters. All chemical reactions involving cellulose, the main active constituent of paper, are occurring with the participation of this polysaccharide’s glucose radicals. Cellulose depolymerisation, as well as its further chemical decomposition, is most of all a result of hydrolysis, oxidation, or enzymatic action of microorganisms. The course of the hydrolysis is complex and occurs gradually: from cellulose to the end product which is glucose. However, the oxidation process causes the transformation of hydroxyl groups in cellulose into aldehyde groups, ketone groups and carboxylate groups. In case of metal ions, for example those coming from printing or handwriting ink, both the above-mentioned processes may occur simultaneously. Hydrogen ions catalyze the hydrolysis and metal ions catalyze the self-oxidation. Those processes allowed to form a thesis concerning the irreversible destruction of paper cellulose, which is catalyzed in the acidic environment. They cause the loss of paper’s mechanical durability, and thereby the irretrievable decay of handwritten and printed documents. Still, the unexamined issue remains the influence of ingredients contained in the auxiliary substances of paper on the mechanism and reaction kinetics of the paper ageing process. That is the source of interest in adhesives used in manufacturing process of the historic printing paper. Up until now, the decay of adhesives that accompanies the paper ageing process has not been taken into account. By the same token, the synergistic interaction of both the processes is not a widely-known fact. The conservation of historic books requires the basic knowledge of physicochemical and mechanical condition characterizing the material they are built of. The development of instrumental — in particular chromatographic — analytical techniques creates a possibility to carry out research the results of which can be applied in book conservation practice. The examination of antique books must not lead to damaging thereof. After examination, a restored material should be again included in a library collection. It seems that chromatographic techniques comply with the above-mentioned requirements. They can be successfully utilized in so-called conservation materials science. The presented work is an attempt to include chromatography into the conservation practice of antique library material. Gas chromatography has rapidly become a dominant method in qualitative and quantitative research. However, it requires transforming fatty acids into volatile aliphatic esters which, in turn, have numerous advantages. They are non-polar and produce sharp, well-shaped peaks. By using mass spectrometer, it becomes possible to measure their molecular mass as well as the degree to which the acyl radicals are unsaturated. The primary aim of this work was to device selected chromatographic techniques for marking natural components of adhesives contained in antique library material as well as in the products of their transformation that constitute another element of their natural ageing process. The data thus obtained should allow to elaborate the bases of the mechanism of this process and its influence on structural and mechanical parameters of antique library material. Such a knowledge will facilitate deciding on the scope of the conservator’s interference and the selection of the right materials or their contemporary natural substitutes. The division of methyl esters was performed using the capillary columns of a gas chromatograph with the flame ionization detector (FID) and with the mass spectrometer (MS). The mass spectrometer was equipped with the EI ion source that has the maximal ionization energy of 70 eV. It worked in the full-scan mode, monitoring the mass from 50 to 480 amu. Another so far unexamined problem is the mechanism of the natural paper ageing process in the area of auxiliary substances which include animal glue applied by historical paper makers. Also in this case we deal with oxidation of elements of adhesives, especially the unsaturated ones. Here, there have to be included all the lipid structures created by unsaturated fatty acids. In animal glues, however, the unsaturated lipid substances are dominant, and that is why free radical oxidation reaction is not dominant. This fact is indirectly confirmed by the identity analysis of products contained in hexane extractions from antique papers. Oxygen-containing derivatives of fatty acids were identified incidentally, depending on the applied animal glue and the contents of the oleic acid. The considerable contents of the products of transformation of the lower aliphatic acids’ and dicarboxylic acids’ auxiliary substances suggests that oxidation of unsaturated acids and the hydrolysis of epoxy connections are not the only sources of their origin. The similar result can be achieved with the oxygen during pyrolysis occurring as the effect of light and temperature. A specific parameter of all the chemical reactions taking place in the material under examination is also the reaction time, identical with centuries-old exposure of paper. Another open research problem is the possibility of co-oxidation of the unsaturated fatty acids with the oxidized cellulosic hydrolysates, particularly with the structure of aldehyde, which in this case can be a supplier of oxygen for creating peroxide connections. The disintegration of peroxides is not very selective and it yields diversified mixtures of products. In this way, the extractions of antique papers display their qualitatively diversified character. It is hard to estimate to what extent this process is stimulated by the lipid substances from glue that are evenly distributed on the entire surface of paper. Explaining its mechanism, one should take into account the presence of metallic oxide called siccative (which is a drying agent for the printing ink) in the linseed oil. In this diversified kinetic environment the siccative can serve as supplier of metal ions mainly catalyzing self-oxidation. Unsurprisingly, the phenomenon of colourings of the entire surfaces most often occurs on the books’ initial and final pages, since those places are easily accessed by light, water vapor and oxygen from air. The application of gas chromatography allowed to exclude microbiological causes for the occurrence of this defect.