ANALYTICAL CHEMISTRY
470 Interfacial Angles (polar). 110 A 710 = 53' 32' (x-ray), 201 A001 = 45'. x-R.4~DIFFRACTIOS DATA Cell Dimensions. a = 16.71 A.; b = 8.43 -4.; c = 6.94 A. Formula Weights per Cell. 2(2.03, x-ray). Formula Weight. 370.4 (monohydrate). Debity. 1.277 grams per cc. (flotation), 1.292 grams per cc. (s-rav). OPTICALPROPERTIES Refractive Indices. 15803 -1.. 25' C.). o( = 1.580. 4 = 1.680. y = 1.683. 27' = ( ) 16' (calcd. from a,8, and y), Optic Axial Angles. 18" (calcd. from p and Mallard's constant), 2E = 31'. Optic Bxial Plane. Perpendicular to 010. Acute Bisectrix. cy. Extinction. cy A c = 30' in obtuse B. Dispersion. v > r , large. FUSION DATA.On heating, ajmalicine hydrate loses water in the range 110' t o 120' C. to give the anhydrous form.
FUSIOX DATA. On heating, tetrahydroserpentinol melts a t 244" C. with decomposition. X-RAY POWDERDIFFR4CTION DATA. hll powder diffraction data were obtained using a camera 114.6 mm. in diameter and chromium radiation with vanadium pentoxide filter. A wave-length value of 2.2896 .4. was used in the cslculations. ACKNOWLEDG\.IENT
The author is indebted to Yorbert Neuss of these laboratories for supplying the crystals used in this work. LITERATURE CITED (1) (2) (3) (4)
Bader, F. E., and coworkers, J . Am. Chem. SOC.,76, 1695 (1954). Klohs, 11.W., and coworkers, Ibid.,76, 1332 (1954). Neuss. Xorbert. and coworkers. Ibtd.. 76. 3234 (1954). Weisenborn, F. L., and coworkers, Chemistry and I n d u s t r y , 73, 375 (1954).
py-TETRAHYDROSERPENTINOL
CRYST.4L RIORPHOLOGY Crystal System. Orthorhombic. Form and Habit. Blades lying on 010 elongated parallel to a and showing the forms macropinacoid ( l o o ) ,brachydome ( O l l ) , and brachypinacoid ( 0101. Cleavage. Good, parallel to 100. Axial Ratio. a : b : c = 0.4138: 19.3929 (,-ray). Interfacial Angle (polar) 011 A 011 = 42" 54 . X-RAYDIFFRACTION Cell Dimensions. a = 11.50 .4.; b = 27.79 A4.; c = 10.92 A. Formula Weights per Cell. 8(7.99, x-ray). Formula Weight. 324.4. Density. 1.233 grams per cc. (flotation), 1.235 grams per cc. (x-ray).
Figure 3. Orthographic projection of py-tetrahydroserpentinol
OPTICALPROPERTIES Refractive Indices (5893 A , , 25" C.). cy = 1.590, = 1.68 (est.). Optic hxial Angle. 271 = ( + ) 60' (est.) Optic hxial Plane. 100. Acute Bisectrix. y = b. Dispersion. r > v.
= 1.613,
X-Ray Powder Diffraction Data for py-Tetrahydroserpentinol d
I/Il
hlcl
d(Ca1cd.)
13.90 10.15 8.86 8.57 7.61
0.53 0.20 0.66 0.20 0.27
020 011 120 021 111
13.90 10.15 8.86 8.59
7.62
5.91
5.19 4.86 4.78 4.63 4.41 4.35 4 09 3 92 3.81 3.64 3.53 3.44 3.36 3.06 3 01 2.967 2.8fi0 2.633
0.03 0.03 0.13 0 03 0.07 0.03 0.03 0.03
.. .. ..
MEETING R E P O R T
Society for Analytical Chemistry HE Western Section of the society met November 13 a t Cardiff, Wales, when the following paper was presented and discussed.
Gas-Phase Chromatography a s an Analytical Technique. C. J. HARDY,Department of Chemistry, University of Bristol, Bristol. T h e development of gas-phase chromatography as a technique for the separation and estimation of volatile substances was described. The basic principles were briefly outlined and apparatus and practical methods of analysis described in detail. Separations of substances by differential adsorption on, or desorption from charcoal and similar adsorbents were compared with those obtained by t h e newer James and hlartin technique on gas-liquid partition columns. Intensive research by many workers during the last 2 years on t h e development of apparatus and the semimicroanalysis of gases and liquids was summarized. Examples to illustrate the methods and results were given from the author's own work on the separation and determination of halogenated hydrocarbons, aliphatic hydrocarbons, and alkyl esters. Gas-phase chromatography has been shown to be applicable to specific problems such as the analysis of intermediates and final products in gaseous reactions. An example of the analysis of products in a gaseous reaction between ethyl nitrite and nitrogen dioxide was given in detail. Gas-phase chromatography was compared with fractional distillation and mass and infrared spectrometry a s a technique for t h e separation of closely related compounds and complex mixtures. I t s use for the preparation of certain pure substances was considered. T h e advantages of gas-phase chromatography over other analytical methods and its potential applications in many fields were discussed.
The tenth annual general meeting of the Physical Methods Group, held November 30 in London, presented a discussion on possibilities in the establishment of standard samples for the determination of some trace elements. Topics mentioned included the use of square wave polarography and radioactivation analysis, involving lead in foodstuffs, and minor elements in analytical reagents, pure metals, ferrous and nonferrous alloys, and rocks and minerals. A joint meeting of the Society for Analytical Chemistry and the Oils and Fats Group of the Society of Chemical Industry was held December 1 in London, devoted to the subject of methods for the chemical determination of vitamin A. Determination of Vitamin A in Natural Products and Especially Cod Liver Oil. R. A. MORTON,Department of Biochemistry, T h e State Vitamin University, Liverpool, A N D F. BRO-RASMUSSEN, Laboratory, Copenhagen. I n view of t h e lack of official recognition of vitamin A1 it is not perhaps desirable t o express the results of spectrophotometric assays in terms of total vitamin A activity without indicating how much is due to vitamin A?. Liver oils from salt fish in general have a t least 90% of the total activity supplied by vitamin AI.
V O L U M E 2 7 , NO. 3, M A R C H 1 9 5 5
47 1
T h e analytical procedures of t h e British and United States Pharmacopeias were discussed in relation to t h e historical setting and the newer problems arising out of the presence of three vitamin A-active substances (all-trans arid neovitamin .11and vitamin A p ) in fish liver oils. T h e properties of the three active substances were noted and the combined effects of their intrinsic biological actirities and their absorption spectra were vorked out with special reference to conrersion factors. T h e geometrical correction procedure using the fixation points for all-trans vitamin .$I overcorrects the neovitamin A contribution to t h e total absorption but this is very nearly balanced by t h e lower biological activity of neoritarnin A compared with the all-trans form. Three cod liver oils and two rich oils h a l e been examined by the new chromatographic method of Bro-Rasmussen, Hjarde, and Porotnikoff, which permits quantitative estimate of how t h e total vitamin -4absorption a t 325 mw is distributed between the three active substances. T h e same oils tested on t h e “unsap.” without chromatography but corrected hy the “geometrical” procedure lead t o much t h e same estimate of total vitamin dl potency. Chromatographic Separation of Vitamin A-Active Compounds in Cod Liver oil. F. BRO-RhSMTSSEN. rv. H T A R D EA ,S D OLGAPOROTN I K O F F , State Vitamin Laboratory, Copenhagen, Denmark.
A method was described for preparing dicalcium phosphate for chromatography of fish liver oil uiisaponifiable matter. T h e adsorbent permits a separation of all-trans vitamin A , neoi-itamin -1 and vitamin -42. T h e method recommended for cod liver oil consists of determining the absorption spectrum of the total vitamin A fraction obtained by a single chromatographic separation and determining t h e proportions of t h e three vitamin &active materials by a separate chromatography. Modified Method for Spectrophotometric Estimation of Vitamin A in Margarine. J. W. LORDAND PAULIXE M. BRADLEY, Research Department, J. Bibby & Sons, Ltd., Liverpool. I n principle, the modified method is similar t o t h e official method, but does not require specially activated adsorbents. Commercially available defatted bone meal of appropriate particle size is t h e selected adsorbent. Experiments on margarine show t h a t it is possible t o recover from t h e column a fraction giving spectral absorption substantially t h e same a s t h a t of vitamin A. After a correction for slight irrelevant absorption, results on commercial margarines using the official and modified methods are, for practical purposes, in good argument.
At the 349th meeting of the Physical Methods Group, held January 18 in London, four papers were presented. Solvent Extraction. Introductory Survey. Inorganic Chemistry Laboratory, Oxford.
H . M. N . H . IRVING,
T h e distribution of a substance between two immiscible phases lends itself t o procedures for enrichment or separation; these can be conducted by batch or continuous operation. I t is convenient to distinguish the solvent extraction of inorganic materials under four classes: neutral substances which obey t h e Nernst partition isotherm (iodine or osmium tetroxide); uncharged inner complexes of metals with chelating agents (oxine dithizone. T.T.A.) : mineral acids, their metallic salts, and metal acido complexes; salts or ion pairs incorporating bulky anions or cations (tetraphenylarsonium perrhenate or pertechnetate). Some of t h e difficulties encountered in t h e prac>tical application and -quantitative theoretical treatment of solvent extraction were indicated. Laboratory Apparatus for Solvent Extraction. Energy Research Establishment, Harwell.
I. WELLS,Atoniic
Laboratory equipment for solvent extraction is used t o achieve separation for analytical work and t o investigate and develop new types of solvent extraction processes. Simple separating funnel techniques are suitable when t h e partition coefficients are large in favor of the solvent. When the partition coefficients are small, countercurrent flow is necessary to keep to a minimum t h e number of operations and the volume of extract. T h e advantages and disadvantages of various types of countercurrent equipment were discussed. Two types of isboratory apparatus were demonstrated. Fractionation of Crude Fumagillin by Distribution Methods.
R.
R.G O O D ~ LAND L JCSTCS K. LANDQUIST, Imperial Chemical (Pharmaceuticals), Inc., Manchester. From a strain of Aspergillus fumigatus C. T. Calam isolated fumagillin and a noncrystalline product which also had amebicidal activity. T h e purification of this product was difficult and we submitted it to a countercurrent fractionation t o ascertain whether the
biologicnl activity was due to contamination with fumagillin or to t h e presence of a new amebicide. Distribution in the system bensenepetrol, ethanol-water, demonstrated t h e presence of fumagillin and two other fractions. neither of which had amebicidal activity. There followed the development of distribution methods for t h e bulk purification of crude fumagillin. In this case advantage was taken of the acidic properties of fumagillin for separation from neutral or less acidic impurities by partition between n dilute aqueous buffer solution and a solvent only partly miscible with water. Fumagillin and accompanying impurities are decomposed in aqueous solution above p H 10. so t h a t operating conditions were kept helow thid level. For example, distribution between p H 9 aqueous borax buffer (0.05Jf)and butyl acetate effected substantial purification, so t h a t subsequently fumagillin of purity higher than 90% was isolated in good yield by a fingle crystallization from acetone. Solvent Extraction in the Analysis of Precious Metals. hfcBRYDE, University of Toronto. Toronto Canada.
IT.A . E .
Present-day applications of solvent extraction for the analytical separation of gold and the six platinum metals were summarized. T h e types of compounds mThose solvent extraction was discussed irielude halogen complexes, oxides, complexes with stannous chloride, and organic complexes. T h e choice of method in these cases is usually governed by the environment of the metal being separated and by the subsequent operations in the over-all analysis. Another case of solvent extraction discussed i b t h a t of the metals themselves from reducing fluxes into collecting buttons of lead or other metals as, for instance, in t h e fire assay.
At a joint meeting of the Western Section with the local sections of the Royal Institute of Chemistry, the Society of Chemical Industry, and the Chemical Society, held January 27 a t Brietcl, E. Windle Taylor, Metropolitan Wat’er Board, spoke on “Recent iidvances in the Bacteriological Examination of Water.” Until about 75 years ago the assessment of purity of a water depended upon the chemical analysis. but with the discovery of bacteria and the association of some of them as being the causative agents of disease, a more delicate test for purity became available. T h e chief object of t h e bacteriological analysis of water is to ensure t h a t the water is free from pathogenic bacteria by the time it passes into supply t o consumers. T h e criterion of purity from the bacteriological standpoint has been based on t h e isolation of normal intestinal organisms from water. If it can be shown t h a t a sample is free from bacteria normally present in the human or the animal intestine, it can be assumed t h a t the water is free from disease-producing bacteria. Correct sampling procedure is of importance: otherwise the results of laboratory investigation are worthless. T h e bacteriological analysis is only a part of the investigation of a water supply and t h e results must be interpreted in conjunction with the chemical analysis, inspection of the site, and its history. Improvements in the bacteriological examination of water have been concentrated in recent years on speeding up t h e examination and the present practice for t h e control of water supplies is t o sample more frequently, but limit t h e scope of the examination on each sample. New bacteriological procedures for the isolation of coliaerogenes, and other microorganisms from water were outlined and t h e significance of t h e results was discussed. Finally a plea was made for uniformity in analytical procedure. Report 71, “The Bacteriological Examination of Water Supplies” published by the Ministry of Health, has done much toward this end. Uniformity of methods means uniformity of interpretation and leads t o greater confidence in their value when the results and opinions therefrom are submitted and explained to lay persons.
A lecture on “The Complexones and Their Analytical Application,” accompanied by practical demonstrations was given February 2 in London by G. Schwarzenbach, Zurich University. Ethylenediaminetetraacetic acid ( E D T A , Versene, EK’TA, sequestric acid) is probably t h e most important and versatile organic reagent ever introduced into analytical practice. Yet it is only one of t h e large group of polyaminocarboxylic acids developed a t Zurich by Schwarzenbach and known collectively as t h e “complexones,” which have found widespread use as complexing (masking) agents, in gravimetric and volumetric analysis, in polarography, in separations of rare earths, and in many other fields. I n conjunction with “metal indicators,” many of which were first developed a t Zurich, t h e complexones provide new volumetric procedures for many metals, among which t h e simple and rapid determinations of calcium and magnesium hardness in water is t h e most revolutionary.
