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Zastosowanie metody chromatografii cienkowarstwowej do oznaczania pigmentów nieorganicznych

100%

Wróbel E.

Ochrona Zabytków

1981

issue 3-4

188-196

It was in 1978 that a scientific and research laboratory of the State Enterprise for Monuments Conservation in Warsaw used — for the first time — thin layer chromatography to identify inorganic pigments. Basing on comprehensive literature on the analysis of inorganic ions by means of thin layer chromatography (TLC) nearly 50 methods of the determination of simple ions and their combinations were studied, partially restricting the task to methods of distribution on the most popular carriers. 15 cations entering into the composition of 28 pigments and 1 2 anions entering into the composition of 20 pigments were identidfied. To give all results of the examinations set up in more than 2 0 big tables would exceed the framework of this article. Therefore some details of the examined methods of distribution have been quoted and briefly discussed as representative. When working out methods of the distribution of individual ions or their groups standard pigments and — for comparison purposes — standard salts available in the laboratory were used. Both pigments and standard salts were prepared for spreading on plates by means of proper solvents. Most frequently it was a diluted or concentrated acid and only occasionally a flux or a diluted base. Pigment solutions were prepared and their concentration did not exceed a few per cent (usually 1 per cent solution was employed). Solutions of the examined pigments or corresponding standard salts were spread on plates covered with a layer of a carrier. As a rule Merck’s plates with silicone gel (Kieselgel 60 F22) and a carrier layer (0.25 mm thick) cut from the plates of 20 X 20 cm down to 4 X 9 cm or Merck’s plates with a cellulose carrier (Cellulose F) of 0 .1 mm in thickness and also cut down to 4 x 9 cm were used. Before spreading standards, plates with cellulose were activated in a dryer at 105° С for 10 minÿ plates with silicone gel were activated at 110° С for 1 hour. Standards were spread on plates by means of capillaries, the diameter of which was 0.5 mm. The plates were numbered and then developed in small chromatographic cells (5x3x11 cm) saturated with vapours of the developing system. After developing a chromatogram, the plates were dried in a dryer and developed by spraying with special reagents. Developed chromatograms were photographesd with a Polaroid camera. The obtained results of the studies make it possible to introduce the analysis of pigments by means of thin layer chromatography as a method supplementary to other traditional methods of determination, particularly when only a small quantity of the sample is available and it is composed of several pigments and their determination by traditional methods is impossible.

Zastosowanie chromatografii cienkowarstwowej do oznaczania spoiw olejnych

100%

Baczko K.

Ochrona Zabytków

1981

issue 1-2

86-92

The present work made at a scientific-research laboratory of the State Enterprise for Conservation of Art was aimed at identifying oil binders by means of thin-layer chromatographic analysis. The work presented a survey of techniques employed in the determination of lipids by means of chromatographic analysis on the painted material. The procedure o f the identification of oil binders was worked out on this basis, which made it possible to implement it in conservation practices. Samples o f oils such as linseed oil (cold-pressed), poppy-seed oil (sun-dried, made by Winsor-Newton) and oil coming from the egg yolk were hydrolyzed in the solution o f KOH in methanol at room temperature. After neutralizing, the samples were extracted with chloroform. Solutions of individual oils were then put on chromatograms. Silicon gel (Kieselgel 60) was used as an adsorbent. Gel- covered glass plates (20 x 20 cm or 20 x 50 cm in size, made by Merck), were activated thermically. A number of developing systems were examined, out of which naptha oil: ethyl ether: acetic acid (80:20:1) was considered as optimum. Iodine pairs associated with sulfuric acid proved to be the best developer. The sensitivity of such a methodical procedure was defined at 10~4 g. Basing on the results of the studies, the above procedure was used for painting techniques containing oil binders: non-yellowing medium, traditional medium, oil-casein distemper, yolk distemper, distemper with arabie gum. The effect of various siccatives and inhibiting (cinnabar) and catalyzing (white lead) agents on the results o f determinations was studied in the process o f drying after prior artificial aging of samples. The method obtained makes possible to distinguish the oil technique from yolk and oil-resin techniques.

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2 Ochrona Zabytków

1 Baczko K.

1 Wróbel E.

2 1981

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Zastosowanie metody chromatografii cienkowarstwowej do oznaczania pigmentów nieorganicznych

Zastosowanie chromatografii cienkowarstwowej do oznaczania spoiw olejnych