Identification of cellulose ethers in cultural heritage by means of MALDI-TOF-MS

Abstract

Cellulose ethers used as adhesives in heritage conservation treatments have been successfully identified by means of MALDI-TOF-MS, a technique non-previously applied for this purpose in cultural assets. This is of relevant importance for longterm conservation, as discrimination among the diverse types of cellulose ethers that may have been applied to an asset during conservation treatments is essential in order to guarantee stability of artworks. The proposed method also allows discrimination among these adhesives spread on paper-based artworks, where cellulose ethers have been extensively utilized for many years, overcoming interferences usually occurred due to the cellulosic nature of both adhesive and support. Successful results have been obtained from mock ups and small samples of paper-based original artworks with usual low concentrations of adhesive. FTIR and NMR have been used as complementary analytical techniques. RESEARCH AIMSThis research pursues the identification of cellulose ethers in heritage assets. On the one hand, this article intends to provide a method for the identification of the most commonly used cellulose ethers used nowadays or in the past in heritage conservation: CMC, EC, EHEC, HEC, HPC, MC, MHEC, MHPC. The method must be feasible to be performed in cultural assets. So, identification has to be feasible taking into consideration conservation guidelines and standards for sampling cultural assets. Besides, the method must be useful in the low concentrations usually encountered in heritage assets. Due to the wide use of cellulose ethers in conservation treatments of paper-based assets, the method ought to be suitable to identify the different types of cellulose ethers impregnated on paper supports, avoiding interferences caused by the similar nature of both materials in small and low concentrations when using other methods and techniques described in the literature hitherto.