Suppression of pigment interference in the gas chromatographic analysis of proteinaceous binding media in paintings with EDTA

X‐ray Crystallographic Proof of the Isomer D2‐C84(5) as Trifluoromethylated and Chlorinated Derivatives, C84(CF3)16, C84Cl20, and C84Cl32

“…However, proteins and their constituents, amino acids, are more stable to oxidation, temperature and environmental conditions than other organic materials 4. Among the proteinaceous glues, beef and porcine gelatines, albumin, casein and egg protein are the most widely employed as binding media in tempera paintings 2–4. (Tempera is a painting technique which makes use of protein to agglutinate the pigment.…”

GC/MS in the Characterisation of Protein Paint Binders

“…In the literature, it is reported that, following the reactions with metals, carbonyl groups may be formed on the lateral chain of such amino acids [6]. The interactions with these cations also give rise to interferences during the analytical treatment that are evidenced by changes on the profile of the relative amino acid percentages obtained [7][8][9], and this may obstruct a correct identification of the proteinaceous binder.…”

“…As mentioned in the previous sections, an important interfering agent in the protein analysis in paint samples is the presence of pigments. In fact, the analytical methods may suffer due to pigments that may continuously interact with the medium through the formation of strong complexes [8,9,[11][12][13]30,39,40,42,45]. For example, copper ions in pigments such as azurite have a great affinity for complexing amino acids.…”

“…This step may include the extraction of the proteinaceous matter by an ammonia solution [8], the use of a cation-exchange resin [8,55], a chelating agent [9,41,44], the use of a C 18 resin or the use of barium chloride solution to suppress sulfates [10,81,82]. Table 9.1 reports the methods used to overcome such problems.…”

Application of peptide mass mapping on proteins in historical mortars

“…As there is usually extremely low content of the proteinaceous additives in mortars, the reliable identification of them represents a complicated analytical problem. In most of common analytical methods the identification of proteins is based on monitoring of the ratios of certain amino acids [4][5][6][7][8]; these parameters are not specific enough for individual proteins. Moreover, the protein decomposition is time consuming and the determination of amino acids ratios is not sufficiently reliable because of their modification and losses under the hydrolysis conditions.…”