November, 1945
745
ANALYTICAL EDITION
anhydrous product and then estimating t h e concentrations from t h e values obtained with t h e solutions. ACKNOWLEDGMENT
T h e author wishes t o thank Frances Edel for the nitrogen determinations. LITERATURE CITED
(1) Am. Med. Assoc., “New and Nonofficial Remedies”, p. 114, 1944; Supplement, p. 8.
A
(2) Auerbach, M. E., IND.ENO.CHEM.,ANAL.ED., 15, 492 (1943) ; 16, 739 (1944). (3) Borowsky, H., private communication. (4) DuBois, A. S., Am. Dye-stuf Reptr., 34,245 (1945). ( 5 ) Flotow, E., Pharm. ZentralhaEZe. 83. 191 11942). (6) Hager, 0 . B., Young, E. M.,Flanagan, T. L.,‘and Walker, H. B., paper presented before Spring Meeting of Philadelphia Section A.C.S., June 13, 1945. (7) Hartley, G. S., and Runnicles, D. F., Proc. Ray. SOC.London, 168A,No. 934, 424 (1938). ( 8 ) Kolthoff, I. M., and Sandell, E. B., “Textbook of Quantitative Inorganic Analysis”, pp. 445 ff ., 539 ff ., New York. Macmillan Co., 1936.
Nonfluorescent Lubricant for Fluorophotometry
A R N O L D KOFF
AND
M I C H A E L FREDERICK, C. D. Smith Pharmacal Company, Orange,
IiK
THE determination of thiamine hydrochloride b y the thiochrome method ( I ) , t h e use of a n ordinary stopcock lubricant is precluded because of t h e possibility of introducing extraneous fluorescence. This makes t h e use of a dry stopcock mandatory and thus leads to frequent freezing of t h e stopcock and t o losses due to leakage during centrifuging. Dow Corning stopcock grease (the silicone lubricant) was found suitable for stopcocks in t h e determination of thiamine chloride. It does not increase the fluorescence of t h e blank reading and i t greatly simplifies the manipulation of t h e apparatus. The fluorescence introduced b y a n unlubricated stopcock, a n ordinary stopcock grease, and the silicone lubricant, as read on a Lumetron fluorophotometer is given in Table I. T h e data show t h a t the Dow Corning grease is a satisfactory lubricant for the reaction vessels in the determination of thiamine by t h e thiochrome procedure. T h e use of this grease can be es-
Table 1.
Fluorescence Introduced by Lubricant
Thiamine in Assay Sample, Micrograms
a
N.J.
Lubricant Used 1.5 Xone Blank None Blank None Blank Silicone Blank Silicone Blank Ordinary grease Blank Ordinary grease Set to zero with zero suppressor dial.
Fluorescence Readine 80 0’ 0 0 0 1.8
-
1.2
tended t o other procedures where t h e contamination of t h e assay sample with foreign fluorescent materials is to be avoided. LITERATURE CITED
(1) Comer, R. T., and Straub, G.
J., IND.ERG.CHEM.,. \ N . ~ L . ED.,
3, 380 (1941).
BOOK REVIEWS The Characterization of Organic Compounds. Samue2 Al. McEZvain. 282 pages. The Macmillan Company, 60 Fifth Ave., New York, N. Y. Price, $3.40. McElvain has followed the general outline first used in Kamm’s “Qualitative Organic Analysis” and later preserved in Shriner and Fuson’s “Systematic Identification of Organic Compounds”. Chapter I is an outline of the general steps by which organic compounds are characterized. Chapter I1 is concerned with a few physical methods for purifying samples (recrystallization, distillation), the determination and use of physical constants (melting and boiling points, specific gravity, refractive index, and Rast molecular weight), and directions for the detection of N, S, C1, Br, and I in organic substances, using the sodium fusion or the magnesiumpotassium carbonate fusion. The organization of the material on physical constants might be improved, although the present arrangement is adequately coherent. Chapter I11 is the best section of the book. Solubilities (in water, dilute acids and bases, ether, and concentrated sulfuric acid) are considered in terms of chemical bonding, dipoles and dielectric constants, hydrogen bonds, and the factors influencing acidic or basic strength. This excellent section amply justifies consideration of the text for characterization classes, even with so formidable a competitor as Shriner and Fuson’s book. The reader may wonder, however, whether the sharp distinction between ionic and covalent bonds is desirable in the case of hydrogen chloride (footnote, p. 49), and whether such distinctions, as well as the effects of induction on acidic
strength, might not be discussed in terms of an electronegativity scale. Chapter IV is a discussion of the chemistry of the class reactions. Some exceptions and interferences are noted. The discussion of the reactions of halogen compounds (pp. 87-90) is especially good, as is the treatment of alcohols (pp. 95-98). Chapter V is composed of procedures for the classification tests: the separation of this material from Chapter I\‘ seems sensible, in enabling the student to find experimental details quickly. The omission of a number of the classification reagents used in the Shriner and Fuson system (anhydrous aluminum chloride, ceric nitrate, periodic acid, iodic acid, zinc-ammonium chloride, and mercuric chloride-sodium ethoxide) should not delay a student in solving most “unknowns”. Chapters VI and V I 1 deal with the separation of mixtures and the preparation of derivatives, respectively. The tables of constants and derivatives in most cases are less complete than Shriner and Fuson’s (1940 edition): this is a disadvantage to the analyst who wants a reference book. But the student and his instructor may be inclined t o forgive the shortcomings of the tables in view of the effective way the theoretical matter is presented, the pleasant style of writing, and the easily-read type. About a hundred questions and problems are placed a t the end of chapters. The book will fulfill a long-recognized requirement-namely, the contribution t o the student’s knowledge of general organic chemistry-quite aside from its value as a laboratory manual of analysis. C. W. GOULD
