ANALYTICAL EDITION
April, 1945
In the first a section of ashed film which has been treated ivith hydrochloric acid is compared with the same section before acidification. Any reduction in the number of blue psrtirles can be interpreted as meaning that these destroyed blue particles were ultramarine blue. To accomplish this test the same principle of testing in situ is used. The procedure is as follows: Observe the ashed film slide under the microscope a t 200 magnification, using a square ruled counting slide such as a Whipple eyepiece micrometer and determine the number of blue particles. S e x t place a hydrochloric acid-gel cover glass over the same area, and in 10 minutes again count the number of blue particles. Any decrease in the number can be interpreted as ultramarine blue particles destroyed. This test is of good sensitivity and 5% or less of ultramarine blue in 95y0 cobalt blue can be identified. The test is equally sensitive in cases of complex colored ash pigment mixtures where this ratio of ultramarine blue to cobalt blue exists. The second test, while not so positive as the first, is of considerable value. I t is based on the fact that any ultramarine blue present in the ashed slide film will, on acidification with hydrochloric acid, form a considerable quantity of sodium chloride which will crystallize in the characteristic cubic form and be readily observable under the microscope a t 200 magnification. The procedure is as follows: Gently immerse and withdraw the ashed film slide several times in warm distilled water to remove any sodium chloride already present. Allow the slide to dry. Place a drop of 4 N hydrochloric acid on the ashed film, and set aside to dry normally a t room temperature. When dry observe under the microscope for cubic sodium chloride crystals, particularly along the periphery of the acidified area. I n a mixture of ultramarine blue and cobalt blues, 5y0 or less of ultramarine blue can be identified by this means. However, in the presence of moderate percentages of iron blue, the test is unreliable because the iron blue on acidification also produces some sodium chloride.
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scopic examination under suitable conditions of magnification and illumination. This test is sensitive to as low as 0.25% ultramarine blue a t 200 magnification. A microscopical method for identifying cobalt blues and violets in the presence of ultramarine blue is sensitive in the case of the cobalt blues to as low as 0.250/,. A microscopical method has been developed for testing of hydrogen sul6de in situ. Two microscopical methods, presented for identification of ultramarine blue in the presence of the cobalt blues, are sensitive to about 5% ultramarine blue. These methods can be used in all cases where the color of the ashed pigment mixture precludes visual observation of ultramarine blue and the cobalt blues and violets. LITERATURE CITED
(1) Am. SOC. Testing Materials, Standards, Part 11, pp. 815-16, 1942. (2) Baker, J., J. Oil and Colour Chem. Assoc., 25,242 (1942). (3) Bruce, H. D., Natl. Bur. Standards, Research Paper 7, 127-8 (1928). (4) FOX,J. J., and Bowles, T. H., “Analysis of Pigments, Paints, and Varnishes”, pp. 75-84, London, Ernest Benn, 1927.
(6) Gettens, R. J., and Stout, G. L., “Painting Materials--A Short
SUMMARY
Encyclopedia”. p. 148, New York, D. Van Nostrand Co., 1942. (6) Jameson, F. L., Paint Manuf., 12, 167 (1942). (7) Mattiello, J. J., “Protective and Decorative Coatings”, Vol. 2, p. 23, New York, John Wiley & Sons, 1942. (8) Natl. Bur. Standards, Circ., 95, 14 (1920). (9) SOC.of Dyers and Colourists. Colour Index, p. 310, 1924. (10) Walker, P. H., Natl. Bur. Standards, Mise. Pub., 15, 36 (1916).
I n the absence of the cobalt blues and violets, ultramarine blue can be identified in complex pigment mixtures by micro-
PRESENTED before the Division of Paint, Varnish, and Plastics Chemistry at the 108th Meeting of the AMERICAN CHEMICAL SOCIETY, New York, N. Y.
Microdetermination of Hydroxyl Content of Sugars and Glycosides BERT E. CHRISTENSEN
M
AND
R A Y A. CLARKE, Department of Chemistry, Oregon State College, Cowallis, Ore.
ANY modifications and further applications of the original hydroxyl method of Verley and Bolsing (4), using a mixture of pyridine and acetic anhydride as the esterification agent, have been published. Peterson and West (3) showed that the reagent could also be used for the quantitative acetylation of sugars and sugar derivatives as well BS various other compounds. The procedure was rather flexible. A weighed quantity of the sample was heated a t 37’ to 80” C. in a small tube attached to a condenser, for 24 to 48 hours with a known amount of the pyridine-acetic anhydride mixture (2 volumes of pyridine to 1 of acetic anhydride). The mixture was then poured into ice water and the amount of acid liberated was titrated with standard base. A blank containing no sample was run at the same time. R e s t and co-workers ( 5 ) modified the procedure slightly to be applicable for lipids and hydroxylated fatty acids. Freed and Wynne (1) simplified and shortened the procedure by merely boiling the pyridine-acetic anhydride solution of the sample in an open test tube for 1 minute. When the solution had cooled, it was poured into water. The test tube was rinsed with water and alcohol and the amount of acid liberated was titrated with a standard base, I n a micromethod recently developed in this laboratory by Peterson, Hedberg, and Christensen ( d ) , the esterification is carried out with pyridine and acetic anhydride in a hermetically sealed tube. This method gave satisfactory results with a large number of alcohols, phenols, and polyhydroxy compounds, and is here extended to include sugars and glycosides. The reagents, apparatus, and procedure have been described ( 2 ) . The method has been modified in only two respects: Double the amount of pyridine specified in ( 2 ) is used to aid the solution of the sugars, and reaction time is extended to 48 hours. Two to 4 mg. of sample are taken for analysis and approximately 10 ml. of 0.04 N base are used in the titrations. Using this modified procedure, the data in Table I were obtained. The results are in good agreement with the precision
Table I. Hydroxyl Determination No. of
Sugars Glucose ( l H a 0 ) “ Galactose
Determinations
OH Theory
70 2 2 5 2 2 2 2 2 2 1
42.9 47.2 47.2 47.2 45.3 37.3 39.8 37.8 37.8 31.5
Found OH
-4verage
(Average)
70
Deviation P.p.1000
42.6 45.9 40.2 47.4 43.7 36.6 39.7 37.5 37.5 31.6
3.6 8.7 16.0 15.0 4.6 9.6 2.5 9.3 12.0
Xylose Rhamnose (hydrate) ~~~~~~e (lHtO) Lactose (1HtO) Ra5nose hydrate Glycosides Salicin 2 29.7 29.2 Phloridzin (2Ha0) 2 25.2 25.5 Digitalin 2 20.1 Amygdalin 3HtO) 2 23.3 23.3 Arbutin (1IfrO) 2 29.3 28.6 Aesculin (2HtO) 2 22.6 22.4 a Values for hydrates are not corrected for water content.
...
...
5.0 20.0
...
4.3 17.0 2.2
obtained using ordinary alcohols. Since this method is relatively easily carried out, it gives considerable promise as a tool for analysis of sugars and glycosides. LITERATURE CITED
(1) Freed, M., and Wynne, H. XI., IND. ENG.CHEM.,ANAL. ED.,8, 278 (1936). (2) Peterson, J. W., Hedberg, K., and Christensen, B. E.. Ibid., 15, 225 (1943). (3) Peterson, V. L., and West, E. S., J . Bioi. Chern., 74, 379 (192i). (4) Verley, A., and Bolsing, F.,Ber.. 34. 3394. 3359 I i!Wl). (5) West. E. S..Hoaaland. C. S.,m i l Cultis. G . H . . J . Bioi. Chcm., 104, 627 (1934); PUBLISHED with the approval of llonopraphs PublicJtions Committee 38 Research Paper No 83, School of Science. Departnieut of Chermstry.
