Proteinaceous materials

The quaHty, ie, level of impurities, of the fats and oils used in the manufacture of soap is important in the production of commercial products. Fats and oils are isolated from various animal and vegetable sources and contain different intrinsic impurities. These impurities may include hydrolysis products of the triglyceride, eg, fatty acid and mono/diglycerides proteinaceous materials and particulate dirt, eg, bone meal and various vitamins, pigments, phosphatides, and sterols, ie, cholesterol and tocopherol as weU as less descript odor and color bodies. These impurities affect the physical properties such as odor and color of the fats and oils and can cause additional degradation of the fats and oils upon storage. For commercial soaps, it is desirable to keep these impurities at the absolute minimum for both storage stabiHty and finished product quaHty considerations. 

As with urine, saliva (spumm) is easy to collect. The levels of protein and lipids in saliva or spumm are low (compared to blood samples). These matrices are viscous, which is why extraction efficiency of xenobioties amoimts to only 5 to 9%. By acidifying the samples, extraction efficiencies are improved as the samples are clarified, and proteinaceous material and cellular debris are precipitated and removed. Some xenobioties and their metabohtes are expressed in hair. Hair is an ideal matrix for extraction of analytes to nonpolar phases, especially when the parent xenobioties are extensively metabolized and often nondetectable in other tissues (parent molecules of xenobioties are usually less polar than metabolites). Hair is a popular target for forensic purposes and to monitor drug compliance and abuse. Human milk may be an indicator of exposure of a newborn to compounds to which the mother has been previously exposed. The main components of human milk are water (88%), proteins (3%), lipids (3%), and carbohydrates in the form of lactose (6%). At present, increasing attention is devoted to the determination of xenobioties in breath. This matrix, however, contains only volatile substances, whose analysis is not related to PLC applications. 

Rat (Fischer-344) 4 hr Resp 200 M (increase in protein and lactate dehydrogenase in lavage fluid focal areas of perivascular edema proteinaceous material in the alveoli) Green et al. 1991... 

Evershed, R. P. and N. Tuross (1996), Proteinaceous material from potsherd and associated soils, /. Archaeol. Sci. 23, 429-436. 

Table 1.2 Amino acid composition of proteinaceous materials (w/w %) [2,12]...

A. Andreotti, I. Bonaduce, M.P. Colombini, G. Gautier, F. Modugno, E. Ribechini, Combined GC/MS analytical procedure for the characterization of glycerolipid, waxy, resinous, and proteinaceous materials in a unique paint microsample, Analytical Chemistry, 78, 4490 4500 (2006). 

Of course, only easily available proteinaceous materials could be used in historical materials, particularly egg (whole or either yolk or white), glue (from bovine or porcine bones or skin, but also from rabbit or fish), gelatine, milk, curd, whey, and blood. In the following paragraphs the basic characteristics of the main groups of these proteins are... 

A great part of the organic additives contains various amounts of proteinaceous materials. The identification of proteinaceous binder could help to explain the unusual properties of the mortars, such as high firmness, hydrophobicity of surfaces, and, for frescoes, high stability [24]. 

These techniques are also not affected by the constraint of having small samples and are sensitive to the kind of proteinaceous material, even if the latter is present in mixtures with other organic materials. These techniques are said to be destructive as they necessarily require the destruction of the sample that cannot be recovered and used for another type of analysis. Nevertheless, for all practical purposes, regarding the very low amount of sample needed and the high specificity of information achieved, they can be considered as micro-invasive. 

In the following sections, common features of gas chromatographic procedures applied to proteinaceous material identification in paint are discussed such as sample pretreatments and data analysis. Finally, a section is devoted to the recognition of the amino acid racemisation in ancient proteins encountered mostly in archaeological contexts. 

GC requires low molecular weight molecules, and the macromolecular nature of proteinaceous materials (made up of 21 amino acids covalently condensed) means that they are typically too large to be readily identifiable and time consuming pretreatments of the sample are required. In order to free the amino acids, hydrolysis is required. Subsequent steps of purification to eliminate pigment interferences are also often necessary. Consequently sample pretreatments must be carefully carried out to reduce the risk of loss and/or contamination of the sample. 

Use of correlation coefficients between amino acid profile data in order to efficiently quantify the degree of similarity between unknown samples and reference proteinaceous materials [7]. The method processes quantitative amino acid concentrations either as per cent relative content (pg g 1 %) or per cent molar content (mol %). A match of more than 0.9 is necessary to ensure a reliable identification of the proteinaceous binder. Table 9.3 reports results obtained on samples coming from the Tintori Collection analysed with two different analytical procedures showing a good correlation with the egg-based binder [96]. 

X. Zang, J.C. Brown, J.D.H. van Heemst, A. Palumbo, P.G. Hatcher, Characterization of Amino Acids and Proteinaceous Materials using Online Tetramethylammonium Hydroxide (TMAH) Thermochemolysis and Gas Chromatography Mass Spectrometry Technique, Journal of Analytical and Applied Pyrolysis, 61, 181 193 (2001). 

Proteinaceous Materials in a Unique Paint Microsample, Analytical Chemistry, 78,4490 4500 (2006). 

Over the centuries the natural organic materials that have best met these requirements are proteinaceous materials (egg, animal glue and casein or milk), polysaccharide gums... 

The following sections discuss in detail the Py-GC/MS of proteinaceous materials, oils and fats, and then briefly plant and animal resins, polysaccharide materials, and beeswax. Particular attention is given to the application of this analytical technique to characterise samples from works of art. At the end of the chapter four case studies are presented. 

Protegrin derivatives, 18 260 Protegrins, 18 260-261 properties of, 18 261 Protein. See also Proteins extraction of, 26 474 in cereal grains, 26 275-276 Proteinaceous materials, as membrane foulants, 21 664 Protein adsorption, 12 136-137 Protein affinity libraries, 12 516-517 Protein-based chiral phases, 6 89-90 Protein-based microarrays, 16 382 Protein biosynthesis, 20 450... 

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