AC
BRIEFS Highlights of the scientific and technical articles in this issue
Analytical Chemistry of Fused Media A summary of the symposium on the Analytical Chemis try of Fused Media is presented. Thirteen papers are summarized dealing with such topics as: Techniques for the Study of Metal-Metal Salt Solutions; Spectrophotome try Applied to the Analysis of Fused Salts; Reference Electrodes for Molten Salts; and others. A Summary of the 1 1 th Annual Summer Symposium. University of Chicago, Chicago, ML, and D. M . National Laboratories, Lemont, III.
N. H. NACHTRIEB, GRUEN, Argonne
Anal. Chem. 3 0 , 1 8 9 2 ( 1 9 5 8 )
Ion Exchange Spectrographic Method for Determination of Impurities in Uranium and Plutonium A new and less hazardous procedure is developed for de termining impurities in uranium and plutonium. T h e sample metal is digested in hydrochloric acid and applied to a Dowex-1 ion exchange column. Impurities are eluted with hydrochloric acid of various normalities and determined spectrographically using the copper spark method. J. K. BRODY, J. P. FARIS, and R. F. BUCHANAN, Argonne National Laboratory, Lemont, ill. Anal. Chem. 3 0 , 1 9 0 9 ( 1 9 5 8 )
X-Ray Spectrophotographic Determination of Tantalum, N i o b i u m , Iron, and Titanium Oxide Mixtures. Using Simple Arithmetic Corrections for Interelement Effects A simple x-ray s p e c t r o g r a p h s method for determining tantalum, niobium, iron, and titanium is devised by precipitating these elements as oxides with cupferron. T h e x-ray analysis employs arithmetic correction factors to compensate for interelement effects. T h e method is applicable to liquid samples as well as ores, metals, and alloys. B. J. MITCHELL, Electro Metallurgical Co., N i a g a r a Falls, Ν. Y. Anal. Chem. 3 0 , 1 8 9 4 ( 1 9 5 8 )
Spectrographic Determination of Boron and Silicon in Low-Alloy Steel by Fluoride Evolution T h e b o r o n and silicon content of low-alloy steel is deter mined spectrographically in their volatile fluoride form. T h e sample is charged with copper fluoride, which de composes w h e n heated, and the fluorine reacts with b o r o n and silicon. Concentrations are obtained by plotting relative transmittance against concentration to form an analytical curve.
Plant-Type Polarographic System for Determining Uranium in Radioactive Waste Streams An automatic p o l a r o g r a p h is used to determine uranium directly in a radioactive process stream of 2Λ1 nitric acid. U r a n i u m (VI) is reduced to uranium (V) at the d r o p p i n g mercury electrode in the nitric acid electrolyte. Nitrite, iron, and tributylphosphate d o not significantly interfere. G. J. ALKIRE, KARL KOYAMA, K. J. H A H N , and General Electric Co., Richland, Wash.
C. E. MICHELSON,
Anal. Chem. 3 0 , 1 9 1 2 ( 1 9 5 8 )
Spectrophotometric Determination of Copper in Ti tanium and Titanium Alloys by Dithizone Extraction A rapid, quantitative spectrophotometric procedure is devised for determining trace amounts of copper in ti tanium and its alloys. N o preliminary extraction is necessary, copper is complexed with dithizone, and this colored complex is extracted in carbon tetrachloride and the density read at 520 ταμ. T h e accuracy and precision are within 1 to 2%· H. W . PENDER, Chase Brass and Copper Co., Inc., Waterbury, Conn.
J. E. PATERSON and W . F. GRIMES, Jones 8. Laughlin Steel Corp., Pittsburgh 3 0 , Pa.
Anal. Chem. 3 0 , 1 9 1 5 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 0 0 ( 1 9 5 8 )
Determination of Tungsten or Molybdenum by X - R a y Emission Spectrography Separation of Uranium from Diverse Ions. Methyl Isobutyl Ketone Liquid-Liquid Extraction System An efficient and selective separation procedure for uranium in the presence of diverse ions is based on the salting out of tetrapropylammonium uranyl trinitrate and extraction with methyl isobutyl ketone. An uranium recovery of greater than 9 9 . 8 % is obtained. Possible interferences from diverse ions are tabulated. W . J. MAECK, G . L. B O O M A N , M. C. ELLIOTT, and J. E. REIN, Phillips Petroleum Co., Idaho Falls, Idaho
T h e tungsten and molybdenum contents of ores or resi dues are determined by x-ray emission spectrography. Tungsten is measured against an internal standard of bromine and the molybdenum determined by measuring the ratio of molybdenum Ka to tungsten L T . Precision is satisfactory. J. E. FAGEL, Jr., H. A. LIEBHAFSKY, and P. D. ZEMANY, General Electric Co., Schenectady, Ν. Υ. Anal. Chem. 3 0 , 1 9 1 8 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 0 2 ( 1 9 5 8 )
Hypophosphorous Acid as a Gravimetric Reagent for Scandium H y p o p h o s p h o r o u s acid is used as a reagent for deter mining scandium because the precipitate scandium hypophosphite possesses a l o w gravimetric factor. T h e presence of other acids of p h o s p h o r u s interfere. Nitrate ions must be eliminated. D. R. BOMBERGER, University of California Radiation Laboratory, Livermore, Calif. Anal. Chem. 3 0 , 1 9 0 7 ( 1 9 5 8 )
Fluorescent X - R a y Spectrometry. Interferences from Compton Scattering from Matrices of Low Atomic Number T h e natures of coherent and Compton scattering of pri mary x-rays in fluorescent x-ray spectrometry are pre sented. They are qualitatively and quantitatively related to the atomic number of the matrix, the wave length of the incident beam, and the geometry of the source-sampledetector system. C. M. J O H N S O N and P. R. STOUT, University of California, Berkeley 4 , Calif. Anal. Chem. 3 0 , 1 9 2 1 ( 1 9 5 8 )
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BRIEFS X - R a y Determination of Sulfur in Oils. Comparison of X - R a y Emission and Absorption Methods
The x-ray spectrograph method for determining sulfur in petroleum products is compared with the iron-5 5 Kcapture x-ray absorption procedure. Both have nearly the same accuracy; the emission method has greater free dom from interference, while the absorption method is less costly. W . R. D O U G H M A N , A. P. SULLIVAN, and R. C. HIRT, American Cyanamid Co., Stamford, Conn.
Improved n-Ethylcarbazole Determination of Carbohydrates with Emphasis on Sea Water Samples
The H-ethylcarbazole method for determining carbo hydrate content of sea water and biological fluids is modified to increase its sensitivity threefold. The method will accurately measure 1 7 of carbohydrate per ml. of sample without interference from high salt con centration. Z. P. ZEIN-ELDIN and B. Z. M A Y , U S. Fish and Wildlife Service, Galves ton, Tex. Anal. Chem. 3 0 , 1 9 3 5 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 2 4 ( 1 9 5 8 )
Determination of Titanium with Cupferron. (Ethylenedinitrilo)tetraacetic Acid as Masking Agent Liquid Scintillation Counting of Radioactive Sulfuric Acid and Other Substances
The sulfur-3 5 content of sulfuric acid is determined by a liquid scintillation counting method. The acid is con verted to a neutral salt and dissolved in a special scintilla tion solution. The counting efficiency is independent of the amine and sulfate present. Other radioactive acids are counted by the technique.
A simple, selective photometric method for determining titanium is based on the masking property of EDTA and complexing capacity of cupferron. Under specific con ditions only titanium, cerium, and uranium complex with cupferron. The complexes are extracted with ketone and as such are absorbed in the ultraviolet region. K. L. CHENG, Kelsey-Hayes Co., N e w Hartford, Ν. Υ. Anal. Chem. 3 0 , 1 9 4 1 ( 1 9 5 8 )
N . S. RADIN and RAINER FRIED, Northwestern University Medical School and Veterans Administration Research Hospital, Chicago, 111. Anal. Chem. 3 0 , 1 9 2 6 ( 1 9 5 8 )
Gas-Liquid Partition Chromatography. Determina tion of 2,6-Di-ferf-butyl-p-cresol on AntioxidantTreated Paperboard Spectrophotometry Determination of p-ferf-Butylcatechol and o-Aminophenol in 2-Methyl-5-vinylpyridine
The /'-ieri-butylcatechol and o-aminophenol in solutions with 2-methyl-5-vinylpyridine are determined by separate colorimetric procedures. The first inhibitor is extracted with ether and sodium hydroxide, air oxidized to the colored quinoid form, and measured at 485 πΐμ. The second is extracted with hydrochloric acid, buffered, then oxidized and measured at 435 πιμ. Κ. Η. NELSON and M. D. GRIMES, Phillips Petroleum Co., Bartlesville, Okla.
The antioxidant, 2,6-di-teri-butyl-/>-cresol, content of treated paperboard is determined by extraction with cyclohexane-isopropyl alcohol and concentration prior to gas-liquid partition chromatography. Over a concen tration range of 14.4 to 144mg. per square foot recoveries of 100 ± 10% 'were obtained. Retention time may be used for the identification of antioxidants and masking compounds. E. C. JENNINGS, Jr., T. D. CURRAN, and D. G. EDWARDS, Fibreboard Paper Products Corp., Antioch, Calif. Anal. Chem. 3 0 , 1 9 4 6 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 2 8 ( 1 9 5 8 )
Potassium Bromide Method of Infrared Sampling
Interfering absorption bands originating in the potas sium bromide pressed window are minimized by using a coarse powder and a gentle grinding technique. Such windows show less matrix absorption and absorption due to absorbed water. The over-all light transmittance is generally higher.
Use of Ion Exchange Resins in the Analysis of Rocks a n d Minerals. Separation of Sodium and Potassium
Sodium and potassium are separated from other con stituents of silicate rock on a cation exchange column of Amberlite IR-120. The sample is digested in hydrofluoric-sulfuric acid mixture, applied to the column, and eluted with 0.12N hydrochloric acid. Other con stituents can be separated by this technique. L. E. RE1CHEN, U. S. Geological Survey, Washington 2 5 , D. C.
R. G . MILKEY, U. S. Geological Survey, Washington 2 5 , D. C. Anal. Chem. 3 0 , 1 9 4 8 ( 1 9 5 8 ) Anal. Chem. 3 0 , 1 9 3 1 ( 1 9 5 8 )
Quantitative Infrared Analysis of Pesticides in the Solid State
An infrared method for analysis of pesticides in solid state is developed. The potassium bromide pellet tech nique is used for study of four pesticides. In each case linearity was found to exist when absorbance.fj. concen tration times thickness was plotted. No internal standard is used. HEINO SUS1 and H. E. RECTOR, Rohm & Haas Co., Philadelphia, Pa. Anal. Chem. 3 0 , 1 9 3 3 ( 1 9 5 8 )
Determination of Zinc by Direct Extraction from Urine w i t h Diphenylthiocarbazone
Zinc is specially extracted from urine with dithizone in carbon tetrachloride. Emulsifying substances are re moved with carbon tetrachloride prior to extraction. The optional pH for the extraction is 5.7. The tech nique compares favorably -with ashing and precipitation procedures and is simple and convenient. Extraneous metals do not interfere. J. H. R. KAGI and B. L. VALLEE, Harvard Medical School and Peter Bent Brigham Hospital, Boston, Mass. Anal. Chem. 3 0 , 1 9 5 1 ( 1 9 5 8 )
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BRIEFS Fractional Sublimation Technique for Separating Atmospheric Pollutants
Determination of Metallic Sodium in the Presence of Sodium Hydride
A fractional sublimation technique is developed for separating large quantities of particulate organic material from polluted air. The technique renders quantitative separation for synthetic mixtures of polynuclear hydrocarbons, but in application to atmospheric samples resinous interference is encountered.
A titrimetric procedure for determining metallic sodium content of mineral oil slurries is described using butyl bromide in hexane as the titrant. This reagent is specific for sodium in the presence of sodium hydride in F ammonia solutions.
J. F. T H O M A S , E. N. S A N B O R N , MITSUGI M U K A I , a n d B. D. TEBBENS, University of C a l i f o r n i a , Berkeley, Calif.
A n a l . Chem. 3 0 , 1 9 7 1 ( 1 9 5 8 )
A. E. MESSNER and L. B. EDDY, Callery Chemical Co., Callery, Pa.
Anal. Chem. 3 0 , 1 9 5 4 ( 1 9 5 8 )
Inorganic Nitrate, Nitrite, or Nitrate-Nitrite. Rapid Colorimetric Determination of Microgram Quantities in Aqueous Solution Chemical Analysis by Measurement of Reaction Rate. Determination of Acetylacetone
A general method of analysis is developed for organic materials based on the kinetics of the reaction involved. Data are obtained during the early stages of the reaction and yield results accurate to 0.3%. The method is applicable to integral-order or complex reactions, such as the determination of acetylacetone. W . J. BLAEDEL a n d D. L. PETITJEAN, University of son, Wis.
Three colorimetric procedures are developed for determining nitrite and nitrate ions individually and in mixtures. The reagent is composed of 2% brucine hydrochloride in 17 or 50% sulfuric acid. In analyses of waters and soils no interfering ions are encountered. The procedures compare favorably with other colorimetric methods. F. L. FISHER, E. R. IBERT, a n d H. F. BECKMAN, Agricultural a n d M e chanical College o f Texas, College Station, Tex.
Wisconsin, M a d i A n a l . Chem. 3 0 , 1 9 7 2 ( 1 9 5 8 )
A n a l . Chem. 3 0 , 1 9 5 8 ( 1 9 5 8 )
A m m o n i u m Molybdate as Spraying Agent for Paper Chromatograms of Reducing Sugars
Ammonium molybdate reagent is used for developing spots of reducing sugars on paper chromatograms. Chief advantages are that no background colors develop and the spot is stable to heat and time. H. EL KHADEM a n d S. HANESSIAN, A l e x a n d r i a University, a n d Starch Products Co., Ud.t A l e x a n d r i a , Egypt
Determination of Reducing Sugars and Reducing End Groups in Polysaccharides by Reaction with Carbon-14-Labeled Cyanide
Reducing sugars are quantitatively determined by reaction with carbon-14-labeled cyanide in a buffered solution. The excess cyanide is volatilized and the radioactivity of the residue measured. Monosaccharides and some disaccharides react with cyanide on a mole equivalent basis; alkali-labile polysaccharides fix more than one mole equivalent. J. D. MOYER a n d H. S. ISBELL, N a t i o n a l Bureau o f Standards, W a s h i n g ton 2 5 , D. C.
A n a l . Chem. 3 0 , 1 9 6 5 ( 1 9 5 8 ) A n a l . Chem. 3 0 , 1 9 7 5 ( 1 9 5 8 )
Solvent Extraction of Chromium w i t h Acetylacetone
Chromium (III) ion is separated from interfering ions contained in ferrous material by virtue of its inert capacity to chelate. Aluminum, iron, vanadium, molybdenum, and titanium are extracted with a 1 to 1 mixture of acetylacetone and chloroform. The chromium (III) in the aqueous residue is converted to the chelate form and extracted with the same solvent mixture, producing a redviolet color. J. P. McKAVENEY a n d HENRY FREISER, University o f Pittsburgh, Pitts, b u r g h , Pa. A n a l . Chem. 3 0 , 1 9 6 5 ( 1 9 5 8 )
Relative Acidities of Organic Acids in Pyridine and Water
A study is undertaken to determine the relationship between titration behavior of acids in pyridine and other low dielectric solvents and their behavior in water. Substituted benzoic acids, aliphatic monocarboxylic acids, dibasic acids, aromatic hydroxyl compounds, and mixtures of dibasic acids are studied in this regard. A number of generalizations which permit prediction of titration behavior are presented. C. A. STREULI and R. R. M I R O N , American C y a n a m i d Co., S t a m f o r d , Conn. A n a l . Chem. 3 0 , 1 9 7 8 ( 1 9 5 8 )
Voltammetric Determination of Histidine
Histidine is polarographically determined by reacting with cobalt (II) at pH 8.0 to form bihistidinatocobalt(II), which gives a well defined one-electron anodic wave at —0.20 volt. The method determines histidine in the presence of other amino acids, histamine, and protein hydrolyzates. BRUNO JASELSKIS, University of Michigan, Ann A r b o r , Mich. A n a l . Chem. 3 0 , 1 9 6 8 ( 1 9 5 8 )
Determination of Perchlorates by Fusion with Nitrite
The exact conditions are set for the fusion of perchlorates with sodium nitrite in two alternate procedures for determining perchlorates. For precision the chloride is potentiometrically titrated in the presence of nitrite— routinely the Volhard method is used. ELISABETH KURZ, GERSHON Defence, Tel-Aviv, Israel
KOBER, a n d
MAX
BERL, Ministry
of
A n a l . Chem. 3 0 , 1 9 8 3 ( 1 9 5 8 )
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BRIEFS Effect of Trichloroacetic Acid on Determination of Silicate and Phosphate with Molybdate Reagent
The color produced by inorganic phosphate and the molybdate reagent is enhanced fourfold when silicate and trichloroacetic acid are present. The molybdate reagent color for silicate is enhanced by the presence of trichloroacetic acid, but to a lesser degree. The analyti cal implication and application of this observation are presented.
Colorimetric Determination of Bismuth in Alloys
A sensitive colorimetric method for determining bis muth in alloys is based on the formation of bismuthAmaranth complex at pH 2.0 to 3-0. This metal-dye precipitate is filtered on a barium sulfate mat and washed with disodium hydrogen phosphate releasing the Ama ranth dye, which is measured at 521 πΐμ. M. P. GROTHEER and J. L. LAMBERT, Kansas State College, Manhattan, Kan.
E. S. DELLAMONICA, E. W . BINGHAM, and C. A. ZITTLE, U. S. Depart ment of Agriculture, Philadelphia 1 8 , Pa.
Anal. Chem. 3 0 , 1 9 9 7 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 8 6 ( 1 9 5 8 )
Measurement of Ionic Strength of Aqueous Solutions by Electrolysis
A new method for determining ionic strength of aqueous electrolyte solutions is developed. An electrolytically generated base is used in the neutralization process and the absorbances of the solution are read at 43 5 and 595 m/i. From the absorbance ratio the ionic strength is calculated. MASAKI NAKANISHI, Ochanomizu University, Tokyo, Japan
Separation of Saturated Hydrocarbons from Petioleum Residues
Saturated hydrocarbons are separated from crude oil residues by absorption chromatography. The residue is dissolved in cyclohexane and applied to a column containing two grades of silica gel. The saturated hydrocarbons are eluted with cyclohexane; asphaltenes and resins are absorbed. R. D. SCHWARTZ Houston, Tex.
and
D. J. BRASSEAUX, Shell Development
Co.,
A n a l . Chem. 3 0 , 1 9 9 9 ( 1 9 5 8 ) Anal. Chem. 3 0 , 1 9 8 8 ( 1 9 5 8 )
Determination of Magnesium Content of Calcium Phosphates and Commercial Lime
The determination of magnesium by precipitation and titration of magnesium 8-quinolinolate is enhanced by substituting sodium for ammonium ions in the procedure. Special precipitation removes the interfering iron, aluminum, and manganese ions. Calcium and phos phates do not interfere in the amperometric titration. D. E. JORDAN and C. F. CALLIS, Monsanto Chemical Co., St. Louis, 24, Mo.
Determination of Dioctyldiphenylamine in Hydraulic Fluids
A colorimetric test for determining/»,^'-dioctyldiphenyl amine in silicon-based hydraulic fluids is described. The amine group reacts with 10% furfural in 2-propanol in the presence of strong sulfuric acid. Amine degrada tion products do not interfere. S. W . NICKSIC and S. H. JUDD, California Research Corp., Richmond, Calif. Anal. Chem. 3 0 , 2 0 0 2 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 9 1 ( 1 9 5 8 )
Carbamate-Ammonia Assay for Novobiocin
A method for the determination of novobiocin is based on the quantitative release of ammonia which is collected by steam distillation. The ammonia is then titrated potentiometrically with 0.0 IN hydrochloric acid. The method is applied to pure samples of novobiocin and its salts. F. A. BACHER, G. V. D O W N I N G , Jr., and J. S. W O O D , Jr., Merck Sharp & Dohme Research Laboratories, Rahway, N. J.
A Thermochromic Test for Polycyclic p-Quinones
A sensitive, specific test for polycyclic quinones involves reduction of the material in dimethylformamide contain ing potassium borohydride. The thermochromic reac tion is reversible, being red, violet, blue, or green at boiling point and yellow, orange, or pink upon cooling. EUGENE SAWICKI, T. W . STANLEY, and T. R. HAUSER, U. S. Department of Health, Education, and W e l f a r e , Cincinnati 2 6 , Ohio Anal. Chem. 3 0 , 2 0 0 5 ( 1 9 5 8 )
Anal. Chem. 3 0 , 1 9 9 3 ( 1 9 5 8 )
Coulometric Titrations in Molten Lithium Chloride-Potassium Chloride Eutectic
Three end point detection methods are studied for use in a coulometric titration procedure for molten salt media. Electrolytically generated iron (III) is a suitable oxidant for the titration. Chromium (II) and vanadium (II) titrations are carried out. H. A. LAITINEN and Β. Β. ΒΗΑΤΙΑ, University of Illinois, U r b a n a , III. Anal. Chem. 3 0 , 1 9 9 5 ( 1 9 5 8 )
Estimation of Boron-10 Burnup by Flame Photometric Lithium Determination
A flame photometric method is developed for determin ing boron-10 in stainless steel, zirconium, and Zircaloy. The procedure analyzes the lithium-7 formed from boron-10 by neutron irradiation reaction. An ammonia precipitation reduces the radioactivity hazard. DRAGOMIR DUTINA, Knolls Atomic Power Laboratory, Ν. Υ.
Schenectady,
Anal. Chem. 3 0 , 2 0 0 6 ( 1 9 5 8 )
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BRIEFS Determination of Phenolic Hydroxyl by NearInfrared Spectrophotometry
The near-infrared region between 2.7 and 3.0 microns offers a convenient tool for the rapid, selective, and sensi tive determination of phenolic hydroxyl compounds. The technique has qualitative and quantitative aspects with accuracy and precision equivalent to those found in other photometric procedures. Particular application is in analysis of phenolic antioxidants. R. F. G O D D U , Hercules Powder Co., Wilmington 9 9 , Del.
Determination of Oxirane O x y g e n in Salts of Epoxy Acids and in the Presence of Amines
Two methods are devised for determining oxirane oxygen in salts of epoxy acids and in the presence of amines. The salt of the epoxy acid is decomposed in acetic acid to the epoxy acid and the metal or amine acetate. The acid is titrated with O.liV hydrogen bro mide or 0.1N perchloric acid. Visual indicators are used to detect the end point. A. J. DURBETAKI, Food Machinery and Chemical Corp., Buffalo 7 , Ν. Υ.
Anal. Chem. 3 0 , 2 0 0 9 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 0 2 4 ( 1 9 5 8 )
Determination of Terminal Epoxides by NearInfrared Spectrophotometry
A rapid determination of terminal epoxides in various mixtures is developed using the near-infrared bonds at 1.65 and 2.20 microns. Terminal olefins are simultane ously determined in the sample. Oxetanes, furans, dioxane, and other oxygen rings do not interfere. Accu racy is in the order of ± 1 to 2 %. R. F. G O D D U and D. A. DELKER, Hercules Powder Co., Wilmington 9 9 , Del.
Estimation of Types Shale-Oil Gas Oil
of
Nitrogen
Compounds
in
A scheme of analysis is devised for separating and characterizing the types of nitrogen compounds in shaleoil gas oil. Molecular distillation and thermal diffu sion techniques are employed for separation and the compounds identified by spectrophotometric, chemical, and physical analyses. Pyridines, dihydropyrindines, indoles, and quinolines are the principal compounds.
Anal. Chem. 3 0 , 2 0 1 3 ( 1 9 5 8 ) G . U. DINNEEN, G. L. C O O K , and H. B. JENSEN, Bureau of Mines, Laramie, W y o .
Spectrophotometric Determination of Iron in Urine, Using 4,7-Diphenyl-l,10-phenanthroline
A specific and simplified procedure employing 4,7diphenyl-l,10-phenanthroline as a color reagent is de veloped for determining iron in urine. Interfering ions are eliminated by extracting the color complex in isoamyl alcohol after wet ashing. The color density is measured spectrophotometrically at 533 πιμ. M. J. SEVEN and RALPH E. PETERSON, National Institute of Arthritis and Metabolic Diseases, Bethesda, M d . Anal. Chem. 3 0 , 2 0 1 6 ( 1 9 5 8 )
Methods of De Saint Venant a n d Mohr and Use of Statistical Criteria
The De Saint Venant and Mohr methods are used for comparing the use of classical and modern statistical treatment of data. Both statistical procedures give essentially equal information. A. G . LOSCALZO, City College, N e w York, N. Y., and A. A. BENEDETTIPICHLER, Queens College, Flushing, Ν. Υ. Anal. Chem. 3 0 , 2 0 1 8 ( 1 9 5 8 )
Analysis of Mixtures of Terephthaloyl a n d Isophthaloyl Chlorides
A differential method for determining terephthaloyl chloride and isophthaloyl chloride in mixtures with the free acids is devised. The acid chlorides are separated in iso-octane and measured by absorption at 227 and 263 ηΐμ. Concentration calculations are made by using simultaneous equations.
Anal. Chem. 3 0 , 2 0 2 6 ( 1 9 5 8 )
Gas-Liquid Chromatography of Hydroxyl and A m i n o Compounds. Production of Symmetrical Peaks
The fundamental causes of unsymmetrical peaks in gasliquid chromatography are investigated. Peak symmetry of polar substances is improved by adding a similar polar material continuously with the carrier gas and operating the column at the proper temperature. H. S. KNIGHT, Shell Development Co., Emeryville, Calif. Anal. Chem. 3 0 , 2 0 3 0 ( 1 9 5 8 )
Rapid Photometric Determination of Fluoride in Water. Use of Sodium 2-(p-Sulfophenylazo)l,8-dihydroxynaphthalene-3,6-disulfonateZirconium Lake
A rapid photometric method for determining fluoride ions in water is devised. The reagent, sodium 2-(psulfophenylazo) - 1,8 - dihydroxynaphthalene - 3,6 - disulfonate—zirconium lake, is specific for fluoride ions. The method is applied to most waters without pretreatment or distillation. ERVIN BELLACK and P. J. SCHOUBOE, U. S. Department of Health, Education, and W e l f a r e , Washington, D. C. Anal. Chem. 3 0 , 2 0 3 2 ( 1 9 5 8 )
E. J. BREDA, E. I. du Pont de Nemours & Co., Gibbstown, N. J. Anal. Chem. 3 0 , 2 0 2 0 (1 9 5 8 )
Determination of Toluenesulfonic Acids in Presence of a n Excess of Sulfuric Acid
pH Adjustment in Colorimetric Iron Determinations
The three isomers of toluenesulfonic acid are determined in excess sulfuric acid by ultraviolet spectroscopy. The isomeric forms absorb at 2220 A. and the total amount of acid is calculated from the mean absorptivity.
In the colorimetric determination of iron with 2,2'bipyridine or o-phenanthroline pH adjustment is made after the reagent is added to the sample solution. The modification eliminates erratic and nonreproducible results.
SHRAGA PINCHAS and PINCHAS AVINUR, The Weizmann Institute of Science, Rehovoth, Israel
N. F. DAVIS, C. E. OSBORNE, Jr., and H. A. NASH, Pitman-Moore Co., Indianapolis, Ind.
Anal. Chem. 3 0 , 2 0 2 2 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 0 3 5 ( 1 9 5 8 )
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BRIEFS Determination of Nitroguanidine by Reduction w i t h Buffered Titanous Chloride
Stable Nitrogen Isotope Analysis by Optical Spectroscopy
An accurate, sensitive method for determining nitro guanidine in raw materials and propellants is described. Nitroguanidine is quantitatively reduced with buffered titanous chloride solution and the excess titanous chlo ride titrated with standard ferric alum solution under an atmosphere of carbon dioxide. Order of addition of reagents to the sample is critical.
A method for the measurement of relative concentrations of nitrogen isotopes in nitrogen gas and nitric oxide gas is presented. Operation conditions of optical spectros copy are studied in reference to precision and accuracy of measurement. Main advantages of this method are short measurement and calculation time, small sample volume, and easy detection of error.
MILTON ROTH and R. F. W E G M A N , Picatinny Arsenal, Dover, N. J.
H. P. BROIDA and M. W . C H A P M A N , National Bureau of Standards, Washington, D. C.
Anal. Chem. 3 0 , 2 0 3 6 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 0 4 9 ( 1 9 5 8 )
Determination of Soluble Chloride in Coal Carbonization Products by W a t e r - M e t h y l Isobutyl Ketone Extraction
The chloride content of crude tar acids, tar acid oil, and tar feed is determined by water extraction from methyl isobutyl ketone. The chloride is then titrated by the Mohr method. Inorganic interferences are removed by precipitation with copper nitrate. LEONARD GINSBURG and L. C. PASZTOR, Jones & Laughlin Steel Corp., Pittsburgh 3 0 , Pa. Anal. Chem. 3 0 , 2 0 3 9 ( 1 9 5 8 )
Specfrophotometric Determination of Microgram Quantities of Indium
Microgram quantities of indium are determined by a spectrophotometric procedure employing 5,7-dibromo8-quinoIinol in chloroform as the reagent. The density of the color complex is measured at 415 πιμ. The absorbance is a strict linear function of concentration over the range from 0 to 100 y of indium. J. E. J O H N S O N , M . C. LAVINE, and A. J. ROSENBERG, Massachusetts Institute of Technology, Lexington, Mass. Anal. Chem. 3 0 , 2 0 5 5 ( 1 9 5 8
Quantitative Studies of Scopoletin in Cigarette Smoke and Tobacco
A quantitative chromatographic procedure is devised for determining scopoletin in cigarette smoke and tobacco. Interfering substances are removed by paper chroma tography from which scopoletin is eluted with 50% ethyl alcohol. The scopoletin content is measured spectrophotometrically at 344 πιμ and calculated from a standard curve. C.-H. Y A N G , YASUSHI N A K A G A W A , versity of Oklahoma, Norman, O k l a .
and
SIMON
WENDER,
Uni
Anal. Chem. 3 0 , 2 0 4 1 ( 1 9 5 8 )
Colorimetric Microdetermination of Nitrogen in Cellulose Nitrates by the Phenoldisulfonic Acid Method
The nitrogen content of cellulose nitrate is determined by colorimetric reaction with phenoldisulfonic acid, which when neutralized yields an intense yellow color. The pH greatly affects the color intensity; optimal pH is 7.1 to 7.5. Color density is read at 400 ηαμ with an accuracy to less than 2 %. L. L. G A R D O N and BENGT LEOPOLD, Industrial Cellulose Research, Ltd., Hawkesbury, Ont., Canada Anal. Chem. 3 0 , 2 0 5 7 ( 1 9 5 8 )
Microbiological A s s a y for Panthenol in Pharmaceutical Vitamin Products
The panthenol content of multivitamin preparations is microbiologically assayed using Leuconostoc mesenteroides P-60 as the functioning organism. Under standard conditions varying concentrations of panthenol produce gradient inhibition to the growth of the organism. Pantothenic acid interferes. O . D. BIRD and LAUREL McCREADY, Parke, Davis and Co., Detroit, Mich.
Titration of Sulfoxides in Acetic Anhydride
Sulfoxides are potentiometrically titrated in acetic an hydride with 0.1 Ν perchloric acid. Reproducible results are obtained for aliphatic, aromatic, and hetero cyclic sulfoxides. Sulfides and sulfones do not interfere. D. C. W1MER, Abbott Laboratories, North Chicago, III. Anal. Chem. 3 0 , 2 0 6 0 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 0 4 5 ( 1 9 5 8 )
Semimicrodetermination of Tantalum with Selenous A c i d
Determination of Reduced Titanium Chlorides in Fused Salt Melts
A method for determining up to 30 mg. of tantalum pentoxide is developed. In a solution of oxalic and tar taric acids tantalum is precipitated with selenous acid and measured gravimetrically. Small amounts of nio bium and titanium coprecipitate and must be corrected for colorimetrically. F. S. GRIMALDI and M . M. Washington 2 5 , D. C.
SCHNEPFE, U. S. Geological
Survey,
Anal. Chem. 3 0 , 2 0 4 0 ( 1 9 5 8 )
Two methods are developed for determining titanium dichloride and trichloride in alkali or alkaline earth mixtures. Both determine total soluble titanium by titra tion with ferric ammonium sulfate. The first is a method of titanium (II) chloride present, while the second per mits determination of the apparent valence of the titanium. SVANTE MELLGREN Sayreville, N. J.
and
Μ.
Β.
ALPERT,
National
Lead
Co.,
Anal. Chem. 3 0 , 2 0 6 1 ( 1 9 5 8 )
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