## 3 Physico-Chemical Analyses  
The material analysis aims primarily to identify the composition of the support, the inks, pigments, dyes, and the binding media that were used for the manuscript production [23; 24; 25] as well as to detect the possible deterioration of the materials [26]. In order to obtain a complete picture of the composition and the preservation status of an object, it is important to correctly merge the results that are obtained by the use of the different analytical methods. Generally, the chemical-material analysis is based on the combination of three complementary spectroscopic methods: X-ray fluorescence analysis (XRF) for the detection of the chemical elements and Fourier Transform Infrared analysis (FTIR) as well as Raman spectroscopy, which are compound-specific methods [27]. The three analytical techniques have strengths and weaknesses [28], resulting on the one hand from the characteristic interactions of the applied radiation with the materials that are analyzed, the penetration depths of the radiation that is used, and on the other hand, from the design of the instruments (e.g., differences in the detectors or the different spot sizes). Therefore, their application is recommended to be performed in a complementary way [29]. The continuous progress in the development of suitable instrumentation for the analysis of cultural heritage items has led to the improvement and proposal of new devices, covering a broad area of materials and objects. The range goes from the study of colors and painting techniques, degradation processes, restoration practices, and the protection/degradation of objects of organic nature such as archaeological wood, paper, textile and proteinaceous materials such as parchment and leather. Moreover, the booming development of the analytical methods in recent decades has brought a great number of new instrumental micro-analytical techniques that are especially suitable for the study of membranous codices [30; 31]. Transportable and handheld instruments allow, nowadays, not only the in situ investigations of the objects, but their sampling is not required anymore (thus, it is non-invasive). This means that there is no need for the original sample material to be taken. The analytical approach starts by applying energy dispersive XRF in air, thereby yielding the qualitative and semi-quantitative results of the elements that are present in the materials. With this method, information about the class of the pigments and inks that were applied can be only deduced from the elements that are detected [32]. For example, the detection of sulfur (S) and mercury (Hg) in a red area leads, definitely, to the identification of the pigment vermilion (HgS). Another example would be the detection of copper (Cu) in a blue area, which points to the application of azurite, which is the only copper-based blue pigment. However, by applying XRF no compound-specific information can be obtained. Therefore, also in the case of calcium carbonate (CaCO\({}_{3}\)), no differentiation between the three modifications (crystallographic structures), calcite, vaterite, and aragonite, is possible. Moreover, artists were often mixing pigments with white to achieve a lighter hue. The mixtures of the inorganic pigments can hardly be completely characterized by elemental specific methods. The detection of lead (Pb) in a red paint layer indicates the presence of red lead (minium--lead oxide). In the case of possible mixture of minium with lead white (lead carbonate) the differentiation of the two materials cannot be clearly identified by just employing XRF. For this reason, a compound-specific analysis is necessary for the identification of the materials. FTIR and Raman spectroscopy have been employed widely in the field. Both techniques are carried out in air, and they are applicable in a non-invasive way. The following are some relevant results that have been obtained from our recent studies of ancient Slavonic manuscripts.