AC BRIEFS Highlights of the scientific and technical articles in this issue
Signifi
Simultaneous Polarographic Determination of Lead and A z i d e Ions of Lead Azides in Aqueous Media
The composition of the viscous fractions of petroleum are analyzed by carbon-type analysis methods. The basic validity of the carbon-type analysis correlations is con firmed. It is indicated that single benzene rings, unfused with naphthene rings or other aromatic rings, do not occur in lubricating oil in large quantities. A need for further analytical data is suggested.
A polarographic method provides an effective technique for the simultaneous determination of both lead and azide ions in lead azide. The time element in analysis is greatly reduced. The method is standardized against the gravi metric procedure.
Carbon-Type Analysis of Lubricating O i l . cance of Pure Compound Data
R. W . K I N G , M . A. KUST, and S. S. KURTZ, Jr., Sun Oil Co., Marcus Hook, Pa. Anal. Chem. 3 2 , 7 3 8 ( 1 9 6 0 )
Reducing Properties of Cerous Ion in Alkaline Media
The properties of cerous ion as a reductant in carbonate solutions are investigated in reaction with ferricyanide and permanganate. An indirect method for determining glucose is based on the use of excess ferricyanide in a carbonate mixture which is titrated with standard cerous sulfate. N. H. FURMAN and A. J. FENTON, Jr., Princeton University, Princeton, N. J. Anal. Chem. 3 2 , 7 4 5 ( 1 9 6 0 )
Current and Titration Efficiencies of Electrically Generated Manganic Ion. Ferric-Manganous Sulfate Dual Intermediate System
The operative electrode processes are studied when manganous ion is electrolytically oxidized in sulfuric acid or mixed sulfuric-phosphoric acid media. Of particular interest is the effects of acidity, electrode material, con centration of manganous salt, and current density on the identity of the anode reactions and on the current effi ciency with which these processes occur. A. J. FENTON, Jr., and Ν. Η. FURMAN, Princeton University, Princeton, N. J. Anal. Chem. 3 2 , 7 4 8 ( 1 9 6 0 )
Electrolytic Determination of Microgram Quantities of Water in Paper
A rapid and accurate electrolytic procedure determines micro amounts of water in paper. The water is vapor ized in an oven and the vapor carried into an electrolytic hygrometer by a dry nitrogen stream. Ammonia and certain organic compounds indicate possible interfer ence. R. G . ARMSTRONG, K. W . GARDINER, and F. W . ADAMS, Continental Can Co., Inc., Chicago 2 0 , III. Anal. Chem. 3 2 , 7 5 2 ( 1 9 6 0 )
J. I. BRYANT and M . D. KEMP, U. S. Army Engineer Research and De velopment Laboratories, Fort Belvoir, V a . Anal. Chem. 3 2 , 7 5 8 ( 1 9 6 0 )
Potentiometric Behavior of a Silver-Plated Platinum Microelectrode Pair
In the titration of silver with iodide, two microelectrodes of different sizes are used to produce a derivativetype peak at the equivalence point. The peak results from differences in stress corrosion at the two electrodes. R. B. HANSELMAN, G. H. SCHADE, Jr., and L B. ROGERS, Massachusetts Institute of Technology, Cambridge 3 9 , Mass. Anal. Chem. 3 2 , 7 6 1
(1960)
Coulometric Titration of Noble Metals with Monothio Ethylene Glycol
Electrolytically generated monothio ethylene glycol is used for the coulometric titration of noble metals. The procedure is more sensitive than the thioglycollic acid method for gold and mercury, and extends the analytical application to include silver, palladium, and platinum. BARRY MILLER and D. N. HUME, Massachusetts Institute of Technology, Cambridge 3 9 , Mass. Anal. Chem. 3 2 , 7 6 4 ( 1 9 6 0 )
Programmed Temperature Gas Chromatography
An equation, expressing dependence of solute retention time on heating rate, mass flow rate of carrier gas, and starting temperature for linear temperature conditions has been derived. Experimental results agree well with those derived by integration by computer. Under identi cal conditions, increasing the liquid phase polarity in creases retention time of each member of a polar homol ogous series by the same amount. STEPHEN DAL N O G A R E and W . E. LANGLOIS, E. I. du Pont de Nemours & Co., Inc., Wilmington, Del. Anal. Chem. 3 2 , 7 6 7 ( 1 9 6 0 )
Measurement of Half-Wave Potentials w i t h Cylindrical Electrodes
Oxidation potentials where mass transfer is diffusioncontrolled are measured by using cylindrical microelectrodes. Cylindrical electrodes do not require shield ing and when employed, uniform concentration is re stored by a short translation of the electrode through the solution. EVAN M O R G A N , J. E. HARRAR, and A. L. CRITTENDEN, University of Washington, Seattle 5, Wash. Anal. Chem. 3 2 , 7 5 6 ( 1 9 6 0 )
Gas Chromatographic Analysis of Nitriles
A gas chromatographic technique is described for the de termination of nitriles. The method uses polar and nonpolar columns which resolve the sample according to boiling points and polarity, and boiling points alone, re spectively. IHOR LYSYJ, Food Machinery and Chemical Corp., Princeton, N. J. Anal. Chem. 3 2 , 7 7 1
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BRIEFS Thermometric Monitor for Chromatographic Streams
A thermistor and differential amplifier are used as a qualitative monitor of chromatographic columns. Quan titative application is possible under certain conditions when the area under the direct temperature vs. volume curve is proportional to the amount of sample. MAX BLUMER, Shell Development Co., Houston, Tex. Anal. Chem. 3 2 , 7 7 2 ( 1 9 6 0 )
Spectrophotometric Determination of Uranium with Benzohydroxamic Acid in 1-Hexanol
Small amounts of uranium are quantitatively determined by complexing the uranyl ion with benzohydroxamic acid at pH 6.2 in aqueous solution. The chelate is extracted into 1-butanol and the absorbance measured at 380 πΐμ. Strong oxidizing and reducing agents and certain ele ments interfere. C. E. MELOAN, PAUL HOLKEBOER, and W . W . BRANDT, Purdue Uni versity, Lafayette, Ind. Anal. Chem. 3 2 , 7 9 1 ( 1 9 6 0 )
Separation of Silver from Cobalt a n d Nickel by Ion Exchange Chromatography
An ion exchange chromatographic procedure is devised for the separation of silver from cobalt and nickel. Em ploying a column packed with Amberlite IR-120, the separation was effected by eluting the silver with a 2% solution of sodium nitrite. R. P. BHATNAGER and R. P. SHUKLA, Holkar College, Indore, India Anal. Chem. 3 2 , 7 7 7 ( 1 9 6 0 )
Determination of Active Hydrogen Using Exchange with Deuterium. Infrared Spectrophotometric Method
A generalized infrared spectrophotometric procedure is devised for determining active hydrogen. The sample is dissolved in an excess of deuterium and the amount of OH in the deuterium phase is measured in the 2.97 micron band; from this the active hydrogen is calculated. Sam ples may be soluble or insoluble in water. W . R. HARP, Jr., Shell Development Co., Emeryville, Calif, and R. C. EIFFERT, Shell Oil Co., Martinez, Calif. Anal. Chem. 3 2 , 7 9 4 ( I 9 6 0 )
Paper Chromatography of Bisphenol A
The principal impurities, including 2,2-bis(4-hydroxyphenyl) propane, found in commercial bisphenol A are separated by paper chromatography. The chromatogram is developed in an atmosphere of 2 5% ammonia and eluted with a 1-propanol-kerosine mixture. Results favorably compare with freezing point depression analysis. G . CHALLA and P. H. HERMANS, Institute for Cellulose Research, Utrecht, Netherlands Anal. Chem. 3 2 , 7 7 8 ( 1 9 6 0 )
Polarographic Determination of Technetium and Ruthenium Radionuclides in Fission Products
Technetium and ruthenium radionuclides are determined in fission products by a rapid polarographic technique. The radionuclides are reduced and made soluble in mercury. The amalgam is separated into carbon tetra chloride and the radionuclides assayed by gammacounting technique. D. L. LOVE and A. E. GREENDALE, U. S. N a v a l Radiological Defense Laboratory, San Francisco 2 4 , Calif. Anal. Chem. 3 2 , 7 8 0 ( 1 9 6 0 )
Determination of O x y g e n in Yttrium Fluoride by a Vacuum Distillation Technique
The total oxygen content of yttrium fluoride is deter mined by vacuum distillation technique. Yttrium fluo ride is distilled at high temperature, the oxygen contain ing compounds in the residue are reduced by the carbon crucible. Carbon monoxide evolved is a function of initial oxygen content. V . M. H O R R I G A N , V. A. FASSEL, and J. W . GOETZINGER, lowa State University of Science and Technology, Ames, lowa Anal. Chem. 3 2 , 7 8 7 (1 9 6 0 )
Twenty-One N e w X - R a y Diffraction Powder Patterns
Standard x-ray diffraction powder patterns are obtained for 21 compounds, most of which contain boron. The diffractometer and Debye-Scherrer methods are used for the analyses. H. G. NORMENT, P. I. HENDERSON, and R. L. SOUTH, Callery Chemi cal Co., Callery, Pa. Anal. Chem. 3 2 , 7 9 6 ( 1 9 6 0 )
Absorption Spectra of Molten Fluoride Salts. Solutions of Several Metal Ions in Molten Lithium Fluoride-Sodium Fluoride-Potassium Fluoride
Procedures are described for the preparation of fluoride salt melts and the recording of their spectra using a hightemperature cell assembly. Spectra are obtained for nickel fluoride, cobalt fluoride, chromic fluoride, praseo dymium fluoride, uranium fluoride, and uranyl fluoride dissolved in molten lithium fluoride-sodium fluoridepotassium fluoride. J. P. Y O U N G and J. C. WHITE, O a k O a k Ridge, Tenn.
Ridge National
Laboratory,
Anal. Chem. 3 2 , 7 9 9 ( 1 9 6 0 )
Application of Diffusion Cells to the Production of K n o w n Concentrations of Gaseous Hydrocarbons
The cell was constructed for continuous monitoring of small radioactive effluent streams. Solution counting of beta-emitters as weak as calcium-45 is possible.
Diffusion cell measurements provide a method, experi mentally simple and reproducible, for providing known concentrations of gaseous hydrocarbons. Diffusion co efficients are determined for 2-methyl-l,3-butadiene, hexane, 1-hexene, heptane, 1-octene, decane, benzene, and toluene. Variables involved in the use of a diffusion tube are investigated and the results used to calculate dif fusion rates.
W . J. BLAEDEL and E. D. OLSEN, University of Wisconsin, Madison, Wis. Anal. Chem. 3 2 , 7 8 9 ( 1 9 6 0 )
A. P. ALTSHULLER and I. R. COHEN, U. S. Department of Health, Educa tion, and W e l f a r e , Cincinnati 2 6 , Ohio Anal. Chem. 3 2 , 8 0 2 ( 1 9 6 0 )
All-Teflon Solutions
Counting
Cell for Flowing
Radioactive
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BRIEFS Separation and Characterization of Polynuclear A r o matic Hydrocarbons in Urban Air-Borne Particulates
A method involving column chromatography and ultra violet, visible, and fluorescence studies of fractions is employed for analysis of urban air-borne particulates. The hydrocarbon content of air-borne particulates from 100 communities indicates close similarity particularly in the ultraviolet-visible regions. A number of hydro carbons are consistently found in air samples. EUGENE SAWICKI, WALTER ELBERT, T. W . STANLEY, T. R. HAUSER, and F. T. FOX, U. S. Department of Health, Education, and W e l f a r e , Cin cinnati 2 6 , Ohio Anal. Chem. 3 2 , 8 1 0 ( 1 9 0 0 )
Phosphate Analysis with the Technicon A u t o A n a l y zer. Selective Orthophosphate and Total Inorganic Phosphate Determinations
Two classical colorimetric methods are adapted to the programming facilities of the Technicon AutoAnalyzer. Orthophosphate and total inorganic phosphate in solutions containing condensed phosphates are analyzed at a rate of 20 samples per hour. Good accuracy and precision are obtained and the procedure is relatively interference free. D. P. LUNDGREN, Lever Brothers Co., Edgewater, N. J. Anal. Chem. 3 2 , 8 2 4 ( 1 9 6 0 )
Spectrophotometric Determination of Fluoride with Thorium Chloranilate Simple Sensitive Test for Compounds Containing the Cyclopentadiene CH_. Grouping. Application to A i r Pollution
Compounds containing cyclopentadiene CH2 groups in air samples are detected by reaction with 1,2-dinitrobenzene. A stable blue to green color results with wave length maxima ranging between 600 to 750 ηΐμ. Analy sis of urban air-borne particulates indicates the presence of fluorine and benzofluorine compounds. EUGENE SAWICKI, T. W . STANLEY and JAMES N O E , U. S. Department of Health, Education, and W e l f a r e , Cincinnati 2 6 , Ohio Anal. Chem. 3 2 , 8 1 6 ( 1 9 6 0 )
Spectrophotometric Determination of Carboxyl in Oxidized Starch
The carboxyl content of starches oxidized by hypo chlorite oxidation is determined by spectrophotometric procedure using methylene blue. The dye binds with the carboxylate ion, influencing the absorbance of the solution at pH 8. Measurements are read at 580 m/i. H. C. CHEUNG, BENJAMIN CARROLL, and C. E. WEILL, Rutgers, The State University, Newark, N. J. Anal. Chem. 3 2 , 8 1 8 ( 1 9 6 0 )
Improved Rapid Determination of Nickel in Soils and Latérites
The nickel content of soils and latérites is determined by a rapid geochemical method. Nickel is reacted with dimethylglyoxime and extracted by benzene-amyl alcohol mixture. The solution is treated with alkali and dimethylglyoxime and the nickel develops a wine-red color in the aqueous layer. A. N. C H O W D H U R Y and B. DAS SARMA, Geological Survey of India, Calcutta, India Anal. Chem. 3 2 , 8 2 0 ( 1 9 6 0 )
Thorium chloranilate is used as the reagent in a sensitive spectrophotometric method for determining fluoride. The fluoride reacts with thorium chloranilate in buffered aqueous methyl Cellosolve and the absorbance measured at either 540 πιμ or 330 πΐμ. Interfering cations are re moved by ion exchange resins. A. L. HENSLEY and J. E. BARNEY II, Standard Oil Co. (Indiana), Whiting, Ind. Anal. Chem. 3 2 , 8 2 8 ( 1 9 6 0 )
Determination of the Sulfonyl Chloride Group in m-Benzenedisulfonyl Chloride
A titrimetric procedure is developed for determining sulfonyl chloride. The sample is hydrolyzed in the presence of pyridine and the liberated sulfonic and hydrochloric acids are titrated with standard sodium hydroxide. J. E. BARKER, C. M. PAYNE, and J. MAULDING, Tennessee Corp., College Park, G a . Anal. Chem. 3 2 , 8 3 1 ( 1 9 6 0 )
Composition of A l u m i n u m Nitrate-Nitric Acid M i x tures by Spectrophotometric Measurements
The use of two absorption measurements enabled the pre diction of free acid and aluminum concentrations to 0.03 and 0.02M respectively, at the ΙΛί range. The ternary system of aluminum nitrate-nitric acid-water is used for the spectrophotometric study. R. W . HENRY and G. L. B O O M A N , Phillips Petroleum Co., Idaho Falls, Idaho Anal. Chem. 3 2 , 8 3 2 ( 1 9 6 0 )
Zirconyl-Alizarin Chelate in Spectrophotometric Determination of Trace Amounts of Fluorine
A simplified spectrophotometric technique is developed for determining trace amounts of fluoride ion in fluoridebearing materials. The method uses a zirconium-sodium alizarin sulfonate reagent and the resulting color complex is measured at 520 πιμ. Concentrations to the order of 0.05 gamma are determined. R. P. ASHLEY, Aluminum Laboratories Ltd., Arvida, Quebec, C a n a d a Anal. Chem. 3 2 , 8 3 4 ( 1 9 6 0 )
Enhancement of the Fluorescence of Progesterone (and Other Steroids) in Sulfuric Acid
The fluorescence of certain steroids in sulfuric acid is enhanced by previously heating in 2N potassium hydroxide. Progesterone fluorescence is increased a hundredfold, while estrogen fluorescence is decreased by the technique. J. C. TOUCHSTONE and TARAS M U R A W E C , University of Pennsylvania, Philadelphia, Pa. Anal. Chem. 3 2 , 8 2 2 ( 1 9 6 0 )
Photometric Determination of Traces of Cobalt in High-Purity Nickel
Trace amounts of cobalt in nickel are determined by a modified nitroso-R method. The cobalt is separated from the nickel before being photometrically determined. The cobalt is converted to cobaltic amine and the nickel is precipitated as hexaminoperchlorate. In high purity nickel 0.001 to 0.02% cobalt is determined. C. L. LUKE, Bell Telephone Laboratories, Inc., Murray Hill, N. J. Anal. Chem. 3 2 , 8 3 6 ( 1 9 6 0 )
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BRIEFS Aromatic A m i n e Impurities in Yellow AB and Yellow OB Food Dyes
A spectrophotometric method is devised for determining aromatic amine impurities in certain food dyes. Amines are separated by acid extraction; from this 2-naphthylamine is separated by column partition chromatography and estimated spectrophotometrically. W . D. C O N W A Y Bethesda 1 4 , M d .
Direct Determination of Sulfonate and Nonsulfonate Sulfur in Spent Sulfite Liquor
Sulfonate and nonsulfonate sulfur in spent sulfite liquor are determined gravimetrically. The nonsulfonate sulfur is oxidized to sulfonate and precipitated as barium sulfonate. The sample is then treated with nitric-perchloric acid, and the sulfonate sulfur oxidized to sulfonate which is precipitated in a similar manner.
a n d E. J. LETHCO, N a t i o n a l Institutes o f Health, A n a l . Chem. 3 2 , 8 3 8 ( 1 9 6 0 )
F. R. FOLEY and L. H. J O H N S O N , Puget Sound Pulp & Timber Co., Bellingham. W a s h . Anal. Chem. 3 2 , 8 5 0 ( 1 9 6 0 )
Determination of O x y g e n - 1 8 in Phosphate Ion
The oxygen-18 content of phosphate ion is determined by a fast and accurate method involving the precipitation of phosphate as trisilver phosphate. The precipitate is pyrolyzed at 1000° C. for 10 minutes and the oxygen evolved is measured in a mass spectrometer. MICHAEL ANBAR, MORDECHAI H A L M A N N , and BRIAN SILVER, The W e i z m a n n Institute of Science, Rehovoth, Israel A n a l . Chem. 3 2 , 8 4 1 ( 1 9 6 0 )
Fractional Thermogravimetric Analysis
A new technique, fractional thermogravimetric analysis, extends the scope of thermogravimetric analysis by providing information on the composition or properties of the volatile matter. The technique is applied to several types of analyses and reproducibility and accuracy of results presented. P. L. WATERS, Commonwealth Scientific and Industrial O r g a n i z a t i o n , Sydney, N e w South W a l e s , Australia
Research
A n a l . Chem. 3 2 , 8 5 2 ( I 9 6 0 )
Rapid Colorimetric Determination of 1 P.P.M. of Thiophene in Benzene. Use of Permanent Color Standards
A rapid colorimetric procedure is developed for determining thiophene in benzene using the basic isatin reaction. The procedure is designed for plant operation by unskilled personnel. The final color is measured against artificial color standards. As little as 0.8 p.p.m. thiophene is determined in 10 minutes time. H. A. BARNETT, C. E. BOLE, a n d C. F. GLICK, U. S. Steel Corp., Monroeville. Pa. Anal. Chem. 3 2 , 8 4 2 ( 1 9 6 0 )
Visible and Infrared Spectroscopic Determination of Trace Amounts of Silicones in Foods and Biological Materials
Two procedures are employed for determining silicones in food, human lung tissue, blood, and animal organs. The colorimetric procedure uses silicon-molybdate complex reduced to the heteropoly-blue color. Qualitative and quantitative results are obtained when the extraction and infrared spectrophotometric technique is used. H. J. HORNER, J. E. WEILER, a n d N. C. ANGELOTTI, Dow Corning C o r p . M i d l a n d , Mich. A n a l . Chem. 3 2 , 8 5 8 ( 1 9 6 0 )
Determination of Trisaturated Glycerides in Fats with Mercaptoacetic Acid
The trisaturated glyceride content of fats is determined by reaction of unsaturated glycerides with mercaptoacetic acid. The complex formed is separated from natural trisaturated glycerides by ammonium salt extraction and ion exchange. Measuring the iodine value gives approximate quantitative results. L. R. ESHELMAN, E. Y. M A N Z O , S. MARCUS, A . E. DECOTEAU, a n d E. G . H A M M O N D , Iowa State University o f Science and Technology, Ames, Iowa A n a l . Chem. 3 2 , 8 4 4 ( 1 9 6 0 )
Thermogravimetric and Differential Thermal Analysis of (Ethylenedinitrilo)tetraacetic Acid and Its Derivatives
The thermal properties of EDTA, its salts, and derivatives are examined by thermogravimetric and differential thermal analysis. The free acid and derivatives all decompose at temperatures between 153° and 265° C. The salts exhibit weight lost at lower temperatures due to the evolution of hydrate-bound water. W . W . W E N D L A N D T , Texas Technological C o l l e g e , Lubbock, Tex. A n a l . Chem. 3 2 , 8 4 8 ( 1 9 6 0 )
Detection of Diphenylamine and Its Derivatives in Spot Test Analysis
A spot test analysis for diphenylamine and its derivatives is based on fusion with hydrated oxalic acid producing a blue color. Fifteen compounds have been analyzed. Carbazole derivatives also respond positively. FRITZ FE1GL a n d DAVID GOLDSTEIN, Ministerio d a Agriculture, Rio d e Janeiro, Brazil A n a l . Chem. 3 2 , 8 6 1 ( 1 9 6 0 )
Colorimetric Determination of Secondary Alcohols by Conversion to Ketones
A colorimetric method for the determination of low concentrations of secondary alcohols in the presence of primary alcohols is based on selective oxidation with potassium dichromate. The primary alcohols yield acids and the secondary alcohols ketones. Only the latter respond to colorimetric 2,4-dinitrophenylhydrazine method. This method is also applicable to determination of ketones in the presence of aldehydes. F. E. CRITCHFIELD a n d J. A. HUTCHINSON, Union C a r b i d e Chemicals Co., South Charleston, W . V a . A n a l . Chem. 3 2 , 8 6 2 ( I 9 6 0 )
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BRIEFS Colorimetric Determination of Low Concentrations of Primary and Secondary Alcohols A general method is described, based on reaction of the alcohols with 3,5-dinitrobenzoyl chloride and subsequent treatment of the esters with a solution of dimethyl formamide and propylenediamine to produce a red quinoidal ion. D. P. J O H N S O N a n d F. E. CRITCHFIELD, Union C a r b i d e Chemicals Co., South Charleston, W . V a . A n a l . Chem. 3 2 , 8 6 5 ( 1 9 6 0 )
Plate Height in Gas Chromatography Experimental evidence is useful in establishing the significance of various plate height equations and their parameters. Emphasis is on the eddy diffusion term, although the effect of pressure gradients is also examined. J. C. G I D D I N G S , S. L. SEAGER, L. R. STUCKI, a n d G . H. STEWART, University o f U t a h , Salt Lake City, Utah A n a l . Chem. 3 2 , 8 6 7 ( 1 9 6 0 )
Spectrophotometric Determination of Betaines and Other Quaternary Nitrogen Compounds as Their Periodides Betaines and other quaternary nitrogen compounds are determined by precipitating as the periodides. The precipitate is dissolved in ethylene dichloride and absorbance in the ultraviolet region is measured. Periodide yield is influenced by iodine concentration, certain anions, temperature, and time. J. S. WALL, D. D. CHRISTIANSON, R. J. DIMLER, and F. R.SENTI,Northern Regional Research L a b o r a t o r y , Peoria, III. A n a l . Chem. 3 2 , 8 7 0 ( 1 9 6 0 )
Separation and Determination of Quaternary Nitrogen Compounds and Other Nitrogenous Substances by Ion Exchange Chromatography. Application to Analysis of Corn Extracts A chromatographic procedure quantitatively separates mixtures of quaternary nitrogen compounds in corn extracts. Following appropriate analytical methods, individual compounds in the effluent fractions are determined. The method is applicable for the separation of amino acids and other nitrogen compounds. D. D. CHRISTIANSON, J. S. WALL, R. J. DIMLER, and Northern Regional Research L a b o r a t o r y , Peoria, III.
F. R. SENTI,
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Separation and Determination of Argon, Oxygen, and Nitrogen by Gas Chromatography Mixtures of argon, oxygen, and nitrogen are separated and determined by gas chromatography. Using a 5A Linde Molecular Sieve column, nitrogen is separated at 2 5 ° C. and the argon-oxygen fraction separated at — 72 ° C. Total analysis time is 16 minutes. E. W . LARD a n d R. C. H O R N , W . R. G r a c e & Co., Memphis, Tenn. A n a l . Chem. 3 2 , 8 7 8 ( 1 9 6 0 )
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