AC BRIEFS Highlights of the contributed articles in this issue
Indirect Ultraviolet Spectrophotometric tion of Phosphorus
Analysis of Rare Earth Mixtures by a Recording Spectrophotometer
Multiple tracing light absorption curves of rare earth chlorides in solution (except lanthanum, promethium, and lutecium), taken with a recording spectrophotom eter, permit direct evaluation of interferences. Most suitable index peaks for analytical purposes are recom mended for each element, and appropriate correction factors for interferences of other rare earths are given. D. C. STEWART and DOROTHY KATO, Argonne National Laboratory, Lemont, III. Anal. Chem. 3 0 , 1 6 4 ( 1 9 5 8 )
Absorption Spectra of Terbium Terbium Chloride Solutions
Perchlorate
and
The spectra of terbium perchlorate and terbium chloride solutions have been recorded in range of 200 to 1200 ηΐμ. The intense absorption at 219.8 ηΐμ follows Beer's law and can be used to determine terbium accurately at low concentrations. E. I. ONSTOTT and C. J. B R O W N , Jr., Los Alamos Scientific Laboratory, Los Alamos, Ν. Μ . Anal. Chem. 3 0 , 1 7 2 ( 1 9 5 8 )
Colorimetric Method for Determining Content of Periodate-Oxidized Starch
Determina
A new spectrophotometric method for traces of orthophosphate is based on ultraviolet absorptivity of decom position products of molybdophosphoric acid. After extraction of the acid with ether-isobutyl alcohol, retro grade extraction with basic buffer solution decomposes molybdophosphoric acid and transfers molybdate to aqueous phase. Measurements are made at 230 ηΐμ. C. H. LUECK and D. F. BOLTZ, W a y n e State University, Detroit, Mich. Anal. Chem. 3 0 , 1 8 3 ( 1 9 5 8 )
Determination of 1,1'-Ferrocene Dicarboxylic Acid in Presence of Ferrocene Monocarboxylic Acid by Infrared Spectroscopy
Ferrocene dicarboxylic acid in a mixture of mono- and dicarboxylic acids can be determined by infrared spec troscopy using the potassium bromide disk technique. Method is accurate to about ± 5 % . E. F. WOLFARTH, Wright-Patterson Air Force Base, Ohio . Anal. Chem. 3 0 , 1 8 5 ( 1 9 5 8 )
Dialdehyde
A rapid method is described for the colorimetric deter mination of low percentages of carbonyl groups in periodate-oxidized starches. A />-nitrophenylhydrazone of oxystarch is precipitated from aqueous solution, filtered, dissolved in ethyl alcohol, and determined spectrophotometrically. C. S. WISE and C. L MEHLTRETTER, U. S. Department of Agriculture, Peoria, III. Anal. Chem. 3 0 , 1 7 4 ( 1 9 5 8 )
Identification of Reclaimed Oils by Statistical Discrimination of Infrared Absorption Data
In an analytical method for discriminating between virgin and reclaimed automotive engine lubricating oils, a statistical function, Qt of infrared absorbances, at 14 wave lengths, of the oils, serves as the discriminant. Method relies on differences in complexity of composi tion of most virgin and reclaimed oils for its success. ANDREW UNGAR, Illinois Institute of Technology, Chicago, III., and A. M. TROZZOLO, University of Chicago, Chicago, III. Anal. Chem. 3 0 , 1 8 7 ( 1 9 5 8 )
X - R a y Fluorescent Spectrometric Determination of Yttrium in Rare Earth Mixtures
X-ray fluorescence techniques are particularly well suited for determination of yttrium in rare earth mixtures. For determination of yttrium in ores, a preliminary rare earth group separation is required. Samples are analyzed in solution form, with strontium added as an internal standard. Results agree well with those obtained by optical emission spectrographic procedures.
Spectrophotometric Microdetermination of Copper in Copper Oxidases Using Oxalyldihydrazide
A new method for determination of copper in copper oxidases uses oxalyldihydrazide and acetaldehyde in ammoniacal solution. As little as 0.2 y of copper per ml. can be determined in presence of protein with a precision of 2 to 3%.
R. H. HEIDEL and V . A. FASSEL, Iowa State College, Ames, Iowa Anal. Chem. 3 0 , 1 7 6 ( 1 9 5 8 )
G. R. STARK and C. R. D A W S O N , Columbia University, New York, Ν . Υ. Anal. Chem. 3 0 , 191 ( 1 9 5 8 )
Emission Spectrometric Determination of O x y g e n in Titanium and Titanium Alloys
An emission spectrometric method for determination of oxygen in titanium is based on direct current arc ex citation of a special electrode assembly which provides a molten platinum bath after arc is initiated. Precision of method is comparable to vacuum fusion or bromination-reduction techniques. Determinations are made in only a fraction of time required by other techniques. V . A. FASSEL and W . A. G O R D O N , Iowa State College, Ames, Iowa Anal. Chem. 3 0 , 1 7 9 ( 1 9 5 8 )
X - R a y Powder Diffraction Data of Several Cobalt A m m i n e Azides
X-ray powder diffraction data are given for six cobalt ammine azides. The x-ray patterns are a simple means of characterizing these preparations. T. B. JOYNER, D. S. STEWART, and L. A. BURKARDT, U. S. Ordnance Test Station, China Lake, Calif.
Naval
Anal. Chem. 3 0 , 1 9 4 ( 1 9 5 8 )
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BRIEFS Quantitative X - R a y Diffraction Analysis
A general theory of quantitative x-ray analysis based on theory of Alexander and Klug is derived and used to suggest several procedures for quantitative analysis. Need for calibration curves sometimes can be eliminated, lines may be used even though there may be superposi tions and several components may be determined simul taneously. L. E. COPELAND and R. H. BRAGG, Portland Cement Association, Chicago, III. Anal. Chem. 3 0 , 1 9 6 ( 1 9 5 8 )
Gas Chromatography. Determination of Constituents in the Study of Azeotropes
Gas chromatographic methods have been developed for quantitative analysis of various mixtures of constituents involved in studies of composition of possible azeotropes. In a study of a number of ternary and quaternary mixtures, gas chromatography techniques give more reproducible results in less time. J. F. HASKIN, G. W . WARREN, L. J. PRIESTLEY, Jr., and V . A. YARBOROUGH, Union Carbide Chemicals Co., South Charleston, W . Va. Anal. Chem. 3 0 , 2 1 7 ( 1 9 5 8 )
Ultraviolet Spectrophometric Determination of Sul f a t e , Chloride, and Fluoride w i t h Chloranilic Acid
The chloranilic acid method for determining sulfate and chloride has been made much more sensitive by measur ing absorption of chloranilic acid solutions at 330 in stead of 530 Γημ. Limit of detection is 0.06 p.p.m. for sulfate and 0.05 p.p.m. for chloride. Fluoride can be determined, but is subject to more interferences. Limit of detection is 5 p.p.m. R. J. BERTOLACINI and J. E. BARNEY II, Standard Oil Co. (Indiana), Whiting, Ind.
ferf-Butyl Hypochlorite for Detection of Nitrogenous Compounds on Chromatograms
A large number of nitrogen-containing compounds of biological interest can be detected on paper chromato grams by forming their N-chloro derivatives with tertbutyl hypochlorite and subsequently spraying with starch-potassium iodide. Method is simple, rapid, and more sensitive than other methods. D. P. SCHWARTZ and M. J. PALLANSCH, U. S. Department of Agri culture, Washington, D. C. Anal. Chem. 3 0 , 2 1 9 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 0 2 ( 1 9 5 8 )
Spectral Absorption of Asphaltic Materials
An exploratory study of absorption of ultraviolet and infrared energy by several asphaltic materials includes consideration of applicability of Beer-Lambert law to asphalts dissolved in a mixture of iso-octane and 1butanol for ultraviolet absorption, and in carbon tetra chloride and thin films for infrared absorption. Typical spectrograms are given for several asphalts. . E. SCHWEYER, University of Florida, Gainesville, Fla. Anal. Chem. 3 0 , 2 0 5 ( 1 9 5 8 )
Gas-Liquid carbons
Partition
Chromatography
of
Fluoro-
Several stationary solvent liquids for gas-liquid partition chromatography of fluorocarbon mixtures have been compared experimentally. Fluorocarbon and chlorofluorocarbon media give better resolution of fluorocarbon mixtures than do hydrocarbon media. A solvent phase of good general application for resolving fluorocarbon mixtures boiling below 150° C. is the ethyl ester of Kel-F acid 8114. T. M. REED III, University of Florida, Gainesville, Fla. Anal. Chem. 3 0 , 2 2 1 ( 1 9 5 8 )
Determination of Arsenic in Hydrocarbon Reforming Catalysts by Neutron Activation
Neutron activation analysis is applied to determination of arsenic in platinum-alumina reforming catalysts at concentrations as low as 1 p.p.m. After irradiation, radioarsenic is separated chemically by distillation of pentabromide with inactive arsenic as carrier and isolated as elementary arsenic. Error of method is about 10% of amount present.
Apparatus for Continuous Electrochromatography
A simple, efficient, adaptable, and economical apparatus has been tested for continuous electrochromatographic separation of various inorganic ions. Stabilization me dium is a tapered sheet of soft, thick, industrial filter paper supported on a block of solidified polystyrene foam. Evaporation is prevented by a loose curtain of polyethyl ene sheeting. H. H. STRAIN, Argonne National Laboratory, Lemont, III.
G . F. SHIPMAN and O . I. MILNER, Socony Mobil Oil Co., Inc., Paulsboro, N . J.
Anal. Chem. 3 0 , 2 2 8 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 1 0 ( 1 9 5 8 )
Ascending Chromatography of Polyphosphates
Variables involved in analysis of polyphosphates by paper chromatography have been surveyed in terms of their effect on R/ values. These variables include: composition of atmosphere, hydration of paper and pH, water content, and kind of alcohol in solvent. An ascending method provided constancy of experimental conditions. G . G. BERG, Brookhaven National Laboratory, Upton, L. Ι., Ν . Υ. Anal. Chem. 3 0 , 2 1 3 ( 1 9 5 8 )
Ion Exchange Paper in Rapid Separation and Identification of Basic A m i n o Acids. Arginine, Histidine, and Lysine from Casein Hydrolyzates
A newly available sulfonic acid-type cation exchange resin paper allows separation of arginine, histidine, and lysine. Its advantages over ion exchange columns are: smaller sample, shorter time for separations, elimination of fraction collecting, and fraction analysis by direct staining. M. M. TUCKERMAN, Rensselaer Polytechnic Institute, Troy, Ν. Υ., and Sterling-Winthrop Research Institute, Rensselaer, Ν. Υ. Anal. Chem. 3 0 , 231 ( 1 9 5 8 )
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BRIEFS Potentiometric Titration of Halide Mixtures
A study is made of potentiometric titration of halide mixtures with silver nitrate. End point detection is based on intersection of straight lines. Inaccuracies from mixed salt formation are reproducible and predict able. Correction factors are calculated by statistical analysis. Limits of detection of one halide in presence of large amounts of another can be determined. A. J. MARTIN, E. I. du Pont de Nemours & Co., Inc., Wilmington, Del. Anal. Chem. 3 0 , 2 3 3 ( 1 9 5 8 )
Potentiometric Titration of Some Organic and Inorganic Bases with Sodium Tetraphenylborate
Organic bases and metal ions which form insoluble tetraphenylborates can be determined quickly and accu rately by potentiometric titration -with sodium tetraphenyl borate using a silver electrode-glass electrode pair. Standard sodium tetraphenylborate solutions were found to be very stable. W . J. KIRSTEN, ADOLF BERGGREN, and KJERSTIN NILSSON, Pharmacia. Ltd., Uppsala, Sweden Anal. Chem. 3 0 , 2 3 7 ( 1 9 5 8 )
Potentiometric Titration w i t h Controlled Current. Application to Coulometric Titrations
The technique of potentiometric end point indication is investigated using controlled current as applied to microgram-level coulometric titrations. Good results are obtained in titration of 40 to 200 y of arsenic with bromine. Technique should find further application in low-level coulometric titrations. J. K. LEE and R. N. ADAMS, Princeton University, Princeton, N. J. Anal. Chem. 3 0 , 2 4 0 ( 1 9 5 8 )
Colorimetric Determination of Acetylcholinesterase Activity
A simple direct spectrophotometric method for deter mination of acetylcholinesterase activity uses a new chromogenic substrate, indophenyl acetate. This com pound is hydrolyzed by enzyme at pH 8.0 to produce a highly colored product. Rate of color formation is dependent on enzyme activity. D. N. KRAMER and R. M. G A M S O N , U. S. Army Chemical W a r f a r e Laboratories, Army Chemical Center, M d . Anal. Chem. 3 0 , 2 5 1 ( 1 9 5 8 )
N e w Titrimetric Determinations of Magnesium and A l u m i n u m Oxinates
Two new titrimetric methods are given for determination of precipitated oxinates. Aluminum oxinate is deter mined by titration with perchloric acid in glacial acetic acid using photometric end point. Magnesium oxinate is dissolved in aqueous acid and the free oxine titrated with copper using amperometric end point detection. R. M . POWERS, R. A. DAY, Jr., and A. L. U N D E R W O O D , Emory Uni versity, Emory University, G a . Anal. Chem. 3 0 , 2 5 4 ( 1 9 5 8 )
Determination of Bis-(beta-chloroethyl) Amines and Related Compounds w i t h 8-Quinolinol
Color reaction between 8-quinolinol and some bis-(/3halogenethyl) compounds can be used for the in vitro study of a number of biological aklylating agents of the nitrogen mustard type. Method is sufficiently sensitive for determination of 0.2 μπιοίε of nitrogen mustard in 1 ml. of test solution. E. G . TRAMS, G e o r g e Washington University School of Medicine, Washington 5, D. C. Anal. Chem. 3 0 , 2 5 6 ( 1 9 5 8 )
Complexometric Titration of Copper and Other Metals in Mixture. 1-(2-Pyridylazo)-2-naphthol (Dye) as Indicator
Total amount of copper and zinc, cadmium, or nickel in solution can be titrated by EDTA with l-(2-pyridylazo)2-naphthol as indicator at pH 2.5 to 10. Zinc, cadmium, or nickel can be titrated directly by EDTA in presence of copper, if copper is reduced and masked by thiosulfate. K. L. C H E N G , Kelsey-Hayes Co., Utica, Ν. Υ. Anal. Chem. 3 0 , 2 4 3 ( 1 9 5 8 )
Determination of Pyrrolic Nitrogen in Petroleum Distillates
An improved colorimetric determination of pyrrolic compounds uses the reaction with /»-dimethylaminobenzaldehyde. Optimum reaction conditions and a standard set of absorptivities have been established for the method which has broad general applicability. Olefins interfere but are removed by preliminary chromatographic sepa ration. M. A. MUHS and F. T. WEISS, Shell Development Co., Emeryville, Calif. Anal. Chem. 3 0 , 2 5 9 ( 1 9 5 8 )
Determination of Alkylpyridines by Infrared Spec troscopy. Rapid Methods of Analysis
Rapid, flexible techniques are described for analysis of synthetically produced alkylpyridines utilizing both sodium chloride and potassium bromide regions of infra red spectrum. High-concentration components are successfully determined by using thin cells, appropriate standards, and base-line method of measuring Jo. Dif ferential spectra are used for detection and identification of impurities. R. L. B O H O N and R A Y M O N D ISAAC, Anderson Physical Laboratory, Champaign, III., and HENRY HOFTIEZER and R. J. ZELLNER, Ansul Chemical Co., Marinette, Wis. Anal. Chem. 3 0 , 2 4 5 ( 1 9 5 8 )
Poised Oxidation-Reduction Systems. Quantitative Evaluation of Redox Poising Capacity and Its Relation to the Feasibility of Redox Titrations
Poising capacity of an oxidation-reduction couple is its capacity to resist a change in the potential as reducing agent is added to the solution. This paper discusses efficiency of redox couples in minimizing change of potential on addition of reductant and evaluates quanti tatively capacity of couples in this behavior. E. R. NIGHTINGALE, Jr., University of Nebraska, Lincoln 8, N e b . Anal. Chem. 3 0 , 2 0 7 ( 1 9 5 8 )
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BRIEFS Determination of Very Small Amounts of Carbon in Metals A study is made of conductometric determination of very small amounts of carbon in metals to improve precision and make it competitive with low pressure combustion. Limitation is blank caused by handling crucible in air. T h r e e methods reduce o r stabilize blanks. Using 2- to 3- gram samples, each will give precise carbon determinations d o w n to 0 . 0 0 1 % . R. E. FRYXELL, General Electric Co., Pittsfleld, Mass. Anal. Chem. 3 0 , 2 7 3 ( 1 9 5 8 )
Recording minations
Colorimeter
for
Microchemical
Deter-
A r e c o r d i n g colorimeter has been designed to make rapid and accurate determinations of light absorption in samples containing 30 cu. mm. of fluid. It consists of a point-light source, an alternating current modulated detector and amplifier, and a servo-recorder. A special rigid carriage h o l d i n g six samples positions samples accurately in light beam. A. K. S O L O M O N and D C. C A T O N , Harvard Medical School, Boston 1 5, Mass. Anal. Chem. 3 0 , 291 ( 1 9 5 8 )
Fractionation of Certain Aromatic Hydrocarbons w i t h Molecular Sieve Adsorbents Molecular Sieve adsorbents of different p o r e sizes can be used to separate certain aromatic hydrocarbons according to shape and size of the molecule. They can also provide information on structure of hydrocarbon molecules. Method is tested with mixtures of pure aromatic hydrocarbons and petroleum fractions in Cis to C 25 range. B. J. MAIR and MUTHU SHAMAIENGAR, Carnegie Institute of Technology, Pittsburgh, Pa. Anal. Chem. 3 0 , 2 7 6 ( 1 9 5 8 )
Determination of Dihydroquercetin in Douglas Fir and Western Larch Wood Dihydroquercetin in Douglas fir and western larch can be determined by a simple colorimetric method using 1- to 2gram samples of heartwood. T h e dihydroquercetin is extracted with boiling water and reduced with zinc and acetic acid. A purple-red color is produced on addition of hydrochloric acid. G . M. BARTON and J. A. F. GARDNER, University of British Columbia, Vancouver, B. C. Anal. Chem. 3 0 , 2 7 9 ( 1 9 5 8 )
Colorimetric Determination of Nitrates A colorimetric method for determination of nitrates in river water and sewage effluent utilizes an alkaline ferrous sulfate reduction of nitrates to ammonia, steam distillation of ammonia produced, and subsequent determination of the ammonia by a pyridine-pyrazolone reagent. P r o cedure is satisfactory for samples containing from 0.01 to 0.1 mg. of nitrate nitrogen.
Mirrodetermirtation of Volatile Aldehydes Volatile aldehydes, particularly those generated by and distilled from ninhydrin oxidations of amino acids, are absorbed in excess sodium bisulfite to form stable c o m plexes. After removal of excess bisulfite with iodine, standard iodine and alkaline buffer are added to oxidize the complex. Excess iodine is back titrated with thiosulfate. I. R. HUNTER ond E. F. POTTER, Western Regional Research Laboratory, Albany, Calif. Anal. Chem. 3 0 , 2 9 3 ( 1 9 5 8 f
Semimicro Hydrogénation with Electrically Generated Hydrogen A simple hydrogénation apparatus, in which hydrogen is generated as needed by automatic electrolysis, is useful for determination of a wide variety of unsaturated functional groups. Electric current used to produce the hydrogen is measured by an electronic coulometer which also operates a recorder. Microsamples can be determined with same precision and accuracy as larger samples. J. W . MILLER and D. D. DeFORD, Northwestern University, Evanston, III. Anal. Chem. 3 0 , 2 9 5 ( 1 9 5 8 )
J. M. PAPPENHAGEN, Kenyon College, Gambier, Ohio Anal. Chem. 3 0 , 2 8 2 ( 1 9 5 8 )
Determination of Free Acid in the Presence of Hydrolyzable Ions In a simple method for routine determination of free acid in hydrolyzable ion solutions, titrations are made to a definite p H using potassium oxalate as a complexing agent. Method is accurate, independent of hydrolyzable ion concentration and requires only simple equipment. G . L. B O O M A N , M. C. ELLIOTT, R. B. KIMBALL, F. O . CARTAN, and J. E. REIN, Phillips Petroleum Co., Idaho Falls, Idaho
Determination of Microgram Quantities of Potassium by X - R a y Emission Spectrograph^ of Ion Exchange Membranes Microgram quantities of potassium ions liberated by g r o u n d mica samples are extracted from solution by a rectangle of cation exchange membrane. Potassium is determined in m e m b r a n e by x-ray emission spectrograph^. P. D. ZEMANY, W . W . WELBON, and G. L. GAINES, Jr., General Electric Research Laboratory, Schenectady, Ν . Υ. Anal. Chem. 3 0 , 2 9 9 ( 1 9 5 8 )
Anal. Chem. 3 0 , 2 8 4 ( 1 9 5 8 )
Determination of Polyisobutylene in Rubber Products As little as 0 . 1 % polyisobutylene in rubber products can be determined by extracting material with acetone, then digesting it in nitric acid to destroy natural and GR-S polymers. After filtration, acid-insoluble polyisobutylene is extracted from fillers with mixed c h l o r o f o r m petroleum ether solvent in presence of a peroxide solution. Solubilized polymer is precipitated with alcohol, dried, and weighed. K. E. KRESS, Firestone Tire & Rubber Co., Akron, Ohio Anal. Chem. 3 0 , 2 8 7 ( 1 9 5 8 )
Chemical Identification of Halide and Sulfate Submicron Particles
in
Individual halide particles d o w n to 50 Α., and sulfate particles d o w n to 1000 A. may be identified specifically with the electron microscope. Each particle gives a charac teristic spot reaction when collected as p r o p e r substrate. Size of resulting spot is approximately a linear function of size of original particle. B. J. TUFTS and J. P. LODGE, Jr., University of Chicago, Chicago 3 7 , III. Anal. Chem. 3 0 , 3 0 0 ( 1 9 5 8 )
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