Highlights ofthe contributed articles in this issue

Highlights of the contributed articles in this issue

Determination of Stigmasterol in Soy Sterols by Radioactive Isotope Dilution Isotope dilution techniques are used to determine stigmasterol in sterol mixtures from soybean oil. Stigmasteryl CI4-acetate of known specific activity is added to the soy sterols. Sparingly soluble stigmasteryl .CI4acetate is isolated and its activity and purity (by bromine analysis) are determined. Stigmasterol concentrations are calculated from the 'ratio of activities. R. A. DONIA, A. C. OTT, and NORMAN DRAKE, The Upjohn Co., Kalomazoo, Mich.

Downloaded by NANYANG TECHNOLOGICAL UNIV on August 25, 2015 | http://pubs.acs.org Publication Date: April 1, 1957 | doi: 10.1021/ac50162a001

Anal. Chem. 2 9 , 4 6 4 (1 9 5 7 )

Polarographic Investigation of Tetrakis(ethy1enethiourea)-Copper(1) Nitrate and of Thiourea-Copper(I) Complexes A polarographic study of several copper (I) complexes of thiourea and tetrakis (ethy1enethiourea)-copper (I) nitrate in buffer solutions and solutions with excess ligand show that the copper(1) state is stabilized by these complexing agents. Half-wave potential is independent of pH. The stability constanis of the complexes are calculated.

T. 1. LANE,

C.S.C., J. V. QUAGLIANO, and ERNEST BERTIN, S. J., University of Notre Dame, Notre Dame, Ind. Anal. Chem. 2 9 , 481 (1 9571

Determination of Stigmasterol in Soybean Sterol Mixtures by Infrared Method Stigmasterol present in soybean sterol mixtures can be estimated directly from the infrared absorption of its trans double bond at 10.3 microns. Accuracy of method is about & 3 % based on sample. Steryl esters interfere. J. L. JOHNSON, M. Kalamazoo, Mich.

F.

GROSTIC, and A. 0. JENSEN, The Upjohn Co., Anal. Chem. 29, 468 ( 1 9 5 7 )

Polarographic Determination of Ammonia and Ethylenediamine Ammonia and ethylenediamine can be determined polarographically because mercury dissolves in dilute solutions of these materials, forming either a complex or mercury (11) hydroxide. The anodic diffusion current is proportional to concentration of amine or ammonia up to 50 x ~ o - ~ MMeasurements . are made in 0.1M potassium nitrate or ammonium nitrate. C. J. NYMAN and R. A. JOHNSCN, State College of Washington, Pullman, Wash.

Morphine-Marme Complex

Anal. Chem. 2 9 , 4 8 3 ( 1 9 5 7 )

Marmi's reagent, cadmium iodide plus potassium iodide, has been used to precipitate morphine since 1867. Present study shows that sensitivity of the test increases with increasing potassium iodide concentration and is dependent on reagent-reactant ratio. As little as 0.1 y of morphine can be detected by a microchemical test. Ultraviolet and infrared spectra, x-ray diffraction pattern, optical rotation, and solubility behavior of the derivative are reported. LEO LEVI, Department of National Health and Welfare, Ottawa, Conada Anal. Chem. 2 9 , 4 7 0 (1 9 5 7 )

Determination of Water in Several Hydrazines The 1.9-micron absorptiori band of water is used to determine water present in hydrazine, monomethylhydrazine, and l,l-dimethylhydrazine by a rapid, differential technique. A range of 0.1 to 1 5 % is attained by varying cell length. Dimethylamine, nitrosodimethylamine, and less than 1% methanol and ethanol do not interfere. H. F. CORDES and C. W. TAIT, China Lake, Calif.

U. S.

Naval Ordnance Test Station, Anal. Chem. 29, 485 (1 9 5 7 )

Spectrophotometric Titration of Oleflns with Electrically Generated Bromine Olefins are determined using electrically generated bromine and a spectrophotometric end point. Advantages of the method are higher sensirivity, no electrical coupling between indicatin and generating circuits, and determination of exact e n 3 points by extrapolation of linear portions of titration curves. Using 3- to 11-mg. samples, a precision of better than 2 % was obtained. J. W. MILLER and D. D. DEFORD, Northwestern University, Evonrton, 111. Anal. Chem. 29, 475 (1 9 5 7 )

Fluorometric Determinatioin of 1 1-Desmethoxyreserpine 1 1-Desmethoxyreserpine, a sedative rincipal from the Rauwolfia species, can be determine% by a fluorometric method. The fluorescence of the compound is greatly increased by reaction with 0.001N ceric sulfate in 0.1N sulfuric acid. From 0.5 to 5 7 may be determined by this method. J. A. GORDON ond D. J. CAMI'BELL, Chicago, 111.

Abbott Laboratories, North Anol. Chem. 29, 488 (1 9 5 7 )

Derivative Polarography of Carbohydrates. Aldopentose Hydrazones

The

Aldopentoses in concentrations from 1 x 10-3 to 2 X 10-2M can be identified and determined b y graphic study of their hydrazone derivatives. values at pH 2.3 are quite different for each aldopentose. Reduction currents are proportional to concentration. Pairs of sugars can also be determined.

x1?f7i

J. W. HAAS, Jr., and C. C. LYNCH, University of Delaware, Newark, Del.

Anal. Chem. 29, 479 (1 9 5 7 )

Spectrophotometric Determination of Tellurium The yellow color produced by tellurium(1V) in concentrated hydrochloric acid is the basis of a simple spectrophotometric method for the determination of from 0.08 to 12 mg. of tellurium per 100 ml. Metal ions which form yellow solutions interfere. M. W. HANSON, W. C. BRADBURY, and J. K. CARLTON, University of Arkansas, Fayetteville, Ark. Anol. Chem. 29, 490 ( 1 9 5 7 ) VOL. 2 9 , NO. 4 , APRIL 1957

9A

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METTLER balances. For further information, circle number 10 A on Readers’ Service Card, page 11 A

10A

ANALYTICAL CHEMISTRY

Analytical Studies on Aging of Isocyanate-Based Foams

Time-Temperature Cooling Curves. Simplifled Determination of Compound Purity

During natural and accelerated aging, isocyanate-based foams are hydrolyzed to form solvent-soluble polymer fragments, an insoluble residue, and carbon dioxide. Polymer fragments and residue are similar in chemical structure to the original form. Amine end groups are also formed. Aging can be followed by extraction studies and color tests for the amine end groups. J. K. BUXBAUM,

E. 1.

Purity speci6cations, which should be a routine adjunct to the reporting of physical and chemical properties, are

most reliably obtamed from time-temperature cooling curves. A simplified procedure using a compact, inexpensive apparatus is described. A new direct method for determimng time at which freezing would have begun in absence of supercooling is presented.

du Pant de Nemours 8 Co., Inc., Wilmingtan, Del.

K. LEROI NELSON, Wayne University, Detroit, Mich. Anal. Chem. 29, 512 ( 1 9 5 7

Anal. Chem. 29, 492 (1 957)


Infrared Analysis of Toluene-2,4-Diisocyanate and Toluene-2,6-Diisocyanate Mixtures Mixtures of toluene-2,4-diisocyanateand toluene-2,6diisocyanate are readily analyzed by infrared absorption. Mixtures containing 5 to 9 5 % of the 2,4-isomer are dissolved in cyclohexane and the bands at 12.35 and 12.70 microns are measured for the 2,4- and 2,6-isomers, res ectively. For more than 95% of the 2,4-isomer, the agsorption band of the 2,6- is measured directly o n the sample. S. 5. LORD, Jr., E. 1. du Pont de Nemaurs & Co., Inc., Wilmingtan, Del. Anal. Chem. 29, 497 ( 1 957)

Estimation of Water in Funiing Nitric Acid ,

Water in fuming nitric acid may be estimated directly by a conductometric titration. The nitric acid is added to a solution of sulfuric acid cai-alystin anhydrous acetic acid in a cell and titrated with a si andardized solution of acetic anhydride in acetic acid. Plot of conductance vs. amount of titrant shows a sharp break at the equivalence point. T. B. HOOVER, Applied Science Labormtarier,Inc., State College, Pa., and A. W . HUTCHISON, Pennsylvania State University, University Park, Pa. Anal, Chem. 29, 518 (1 9 5 7 )

Determination of Acetyl Content of Cellulose Acetate by Near Infrared Spectroscopy Acetyl content of cellulose acetate can be determined rapidty by measuring the infrared absorbance due to residual hydroxyl groups. Samples are dissolved in This pyrrole and measurements made at 1445 mp. near infrared method can be accurately calibrated and its precision is of the same order as the Eberstadt method. J. A. MITCHELL, C. D. BOCKMAN, Jr., and A. Ca., Kingsport, Tenn.

V. LEE, Tennessee Eastman

Anal. Chem. 29, 499 ( I 957)

Spectrophotometric Determination of Zinc-and Other Metals with a,P,y,G-Tetraphenylporphine Trace amounts of zinc in cadmium, magnesium, rare earths, be Llium, iron, yttrium, and alkali metals can be determine7 by utilizing the ,spectrophotometric properties of the zinc complex of .r,B,r,6,-tetraphenylporphine in glacial acetic acid. 0the.r metals can be determined indirectly using this complex. C. V. BANKS and R. E. BISQUE, Iowa !state College, Arnes, Iowa Anal. Chem. 2 9 , 5 2 2 ( 1 9 5 7 )

Analysis of Polyisoprenes by Infrared Spectroscopy Amounts of cis-1,4, trans-1,4, 1,2, and 3,4, additions in polyisoprenes can be determined by measuring the absorbances at 8 . 8 4 , 8.68, 10.98 and 11.25 microns, respectively. Effects of changes of polymerization conditions and catalysts can be determined with certainty by methods given. Compositions of typical polyisoprenes are given. J. 1. BINDER and H. C. RANSAW, Firestone Tire and Rubber Co., Akron 17, Ohia Anal. Chem. 29, 503 ( 1 9 5 7 )

Spectrographic Determination of Lead in Leaded Steel Lead in leaded steel in the range from 0.1 to 0.5% is determined spectrographically by this routine control method. A solutionef 2 grams of sample in nitric acid is used to avoid difficulties caused by composition variations in this type of material. J. E. PATERSON, Jones & Laughlin Ste ?ICorp., Pittsburgh, Pa. Anal. Chem. 29, 526 ( 1 9 5 7 )

Polyanion-Stabilized Diazonium Cations and Diazonium:Spot Test Papers as Analytical Reagents Diazonium cations can be stored for long periods in the dark o n a dry nuclear sulfonic acid ion exchange resin. They can be removed as needed by ion exchange for use as a qualitative and quantitative analytical reagent for determination of certain aromatic compounds. Of a Ifrrge number tested, 2,5-dichlorobenzenediazonium, 4-nitrobenzenediazonium, and 2-carboxy-4-nitrobenzenediazonium were most satisfactory. The diazonium ion of p-arsanilic acid, bound to filter paper as the zirconium salt., is described as a spot test reagent for phenols and amnes. J. L. LAABERT and V.

E.

Spectrophotometric Determination of Rhenium with Alpha-Furildioxime Microgram amounts of rhenium can be determined by intensely colored com lex formed by the reduction of perrhenate by tin(I1) cgloride in the resence of a-furildioxime. Best method uses O.8N H& and 26% acetone solution. Molybdenum interference is removed by the ethyl xanthate-molybdenum extraction method.

CATES, Kansas State College, Manhattan, Kan.

V. W. MELOCHE, R. L. MARTIN, and V I . 61. WEBB, University of Wiscansin, Madison, Wir.

Anal. Chem. 29, 508 (1 9 5 7 )

Anal. Chem. 2 9 , 5 2 7 (1 9 5 7 ) VOL. 29, NO. 4, APRIL 1957

11 A


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12 A

ANALYTICAL CHEMISTRY

Flame Spectrophotometric Determination of Copper, Nickel, and Manganese in Aluminum-Base Alloys A flame s ectrophotometric determination of copper, nickel, a n 8 manganese in aluminum-base alloys can be made by extracting their diethyldithiocarbamates with chloroform and aspirating the extract directly into the flame. Emission intensity of these metals is increased four- to sixfold by the chloroform solution and interference of aluminum is eliminated. J. A. DEAN and CARL CAIN, Jr., University of Tennessee, Knoxville, Tenn. Anol. Chem. 2 9 , 5 3 0 ( 1 9 5 7 )

Volumetric Determination of Sulfate by Titration of Excess lead Nitrate with Potassium Chromate Using Siloxene Indicator Sulfate in solution can be determined accurately by the addition of a measured amount (an excess) of standard lead nitrate solution followed by titration of the excess with otassium chromate. Titration is made in a dark chamfer and light emittl:d b y the siloxene indicator at the end point is measured by a multiplier photometer. Preparation and properties of indicator are given. FREDERIC KENNY, R. B. KURTZ, INGE BECK, and IRENA LUKOSEVICIUS, Hunter College, New York, N. Y. Anal. Chem. 2 9 , 5 4 3 ( 1 957)


Determination of Titaqium in PlutoniumTitanium Alloys From 50 to 500 y of titanium can be determined in a solution containing 5 0 mg. of plutonium by use of hydrogen peroxide. Insoluble plutonium peroxide is removed by centrifuging before the titanium peroxy complex is measured spectrophotometrically.

Determination of Mercury in Presence of Halides: Rapid Amperometric Titration From 0.02 to O.OGM divalent mercury can be determined by simple amperometric titration of iodomercurate (11) ion with bis (ethylenediamine) copper (11) ion. Sodium sulfite is used to rem0i.e oxygen. Standardization is made against pure mercuric oxide. Thiocyanate, chloride, bromide, and iodide d o not interfere.

K.

S. BERGSTRESSER, Los Alamos ScientiRc Laboratory, Loa Alamos, N. M. Anal. Chem. 29, 532 ( 1 9 5 7 )

E.

P. PARRY, State College of Washington, Pullman, Wash. Anal. Chem. 29, 546 (1 9 5 7 )

Polarographic Reduction of Chlorites and Bromates in Anhydrous Ammonia Chlorite can be determined polarographically using liquid ammonia because the chlorite discharge overroltage o n mercury is much less i n liquid ammonia than In water. T h e supporting electrolyte is a solution of ammonium thiocyanate in liquid ammonia. Bromate can also be determined. RENATO CURTl and STEUO LOCCHI, Pavia University, Pavia, Italy Anal. Chem. 29, 534 (1957)

Heavy-Paper Technique for Preparative Chromatography Pure compounds can be isolated o n a gram scale b y a simple paper chromatog.raphic method using sheets of Whatman seed-test paper 1.5 mm. thick. Resolved bands are located by a print made b y pressing a dry sheet of Whatman No. 1 paper to the wet heavy-paper chromatogram. H. H. BROWNELL, J. G. HAMILTON, and A. A. CASSELMAN, Defence Research Chemical Laboratories, Ottawa, Canoda Anal. Chem. 29, 550 (1957)

Hemiketal Formation as a Guide to the Steric Environment of a Ketone Group in Natural Products The environment of a keto group in a complex molecule is determined by measurement of extent of hemiketal formation in methanolic hydrogen chloride and consideration of its ultraviolet and infrared absorption. Extent of reaction of ketone with methanol depends o n steric size and proximity of neighboring groups. Reactivities of a series of ketones have been measured to develop a method. 0.H. WHEELER and J. L. MATEOS, Universidad Nacional Autdnoma d e Mixico, M i x i c o 20, D. F. Anal. Chem. 29, 538 ( 1 9 5 7 )

Microdetermination of Toluenediisocyanates in Atmosphere A sensitive and rapid mei hod for determination of,trace quantities of toluenediisozyanate in air depends on rapid hydrolysis to corresponding toluenediamine derivative. This is diazotized and then coupled with N-l-naphthylethylenediamine to produce a reddish-blue color A portable field kit hr described. 2,3’-Diisocyanato-4,4’dimethylcarbanilide can be determined in the presence of toluenediisocyanate by ii s color reaction i n the ethyl Cellosolve-nitrite-boric acid method. KALMAN MARCALI, E. I. du Pont d e Nemours & Co., Inc., Wilmington, Del. Anal. Chem. 29, 552 ( 1 9 5 7 )

Flame Photometric Determination of Calcium in Biological Material. Effect of l o w level Impurities from Calcium Oxalate Precipitation Calcium in serum is determined routinely by flame photometry after separation of calcium by precipitation as calcium oxalate from a deproteinized solution. Ammonium salts and type of acid affect the flame intensity. A little calcium is lost through solubility. A correction factor for these variables is obtained by including two standards (100y of calcium) with each group of sera. 1. Y. TORIBARA, P. A. D E W N , and H. WARNER, University of Rochester, Rochester, N. Y.

Anal. Chem. 2 9 , 5 4 0 (1 9 5 7 )

Separation and Determination of Microgram Quantities of Zirconium Microgram uantities of zirconium in plutonium alloys are separate! by a double precipitation with p-bromomandelic acid and determined using the color reaction with chloranilic acid If more than 1 5 y of zirconium are present, reproducibility is within 3y0. Method is applicable to zirconium i n other materials. C. E. BRlCKER and G. R. WATEfiBURY, Lor Alamor Scientific Laboratory, Los Alamos, N. M. Anal. Chem. 2 9 , 5 5 8 (1 957) VOL. 219, NO. 4 , APRIL 1957

13 A

NlMlR at work .

,

[Nuclear Magnetic Resonance)

8

of a series...lBS4

H' DATA Sample Volume: .03 cc. Frequency: 30 mc. Field: 7050 gauss Horizontal Scale: .030 gausslinch

SPECTRA OF TWO PREMIUM GASOLINES Hydrogen i n gasoline IS present i n at least live different molecular environments which can be resolved at 7050 gauss. These are:

(I) Protons attached to rromatic rings; (2) Protons attached to doubly bonded carbon; (3ICH1 cr CHI graups bonded directly to an aromatic ring; ( 4 ) C H z or CHI groups adjacent to a doubly bonded carbon; (5) Normal, branched, aed cyclic alkanes; also, aliphatic ride chains attached to aromatic rinbs. Blending variations are revealed below.


GASOLINE BRAND "A"

36

a 3 year progress report

GASOLINE BRAND "B"

Compare these early a n d late examples from Varian's "This is N-M-Rat W o r k " series.' N-M-R Spectroscopy has come this far in three short years. W h e n the spinning sample technique dramatically improved N-M-R resolution, this was reported in the series. W h e n Varian's "Super Stabilizer" extended the timestability of the a p p l i e d magnetic field t o a n almost unbelievable 1 part i n 100 million, this t o o was immediately reported i n $22 of the series. These technical improvements have been achieved w i t h careful attention t o compatibilify; the earliest instruments a r e inherently c a p a b l e o f the high degreeof performance available today. W h e n the series began, there were b u t three Varian Spectrometers i n existence. T o d a y they a r e spread throughout the free w o r l d in Universities, Industry a n d Government. N o t o n l y has the N-M-R series developed into a steady progress report, but in many cases it has included examples which were original contributions t o scientific knowledge - a n unusual occurrence, w e believe, in advertising.

36 of

a series...1957

EXPANDED SPECTRUM

O F A N AVIATION GASOLINE

INTERPRETATION: Under super-high resolution the N-M-Rspectrum of a complex mixture such as gasoline fakes on a startling

new aspect, In addition to the five general regions shown under ordinory resolution, the presence of specific compounds such as benzene (peak A) can be deduced. The present interpretation of the spectrum below i s that there are at least two

species of cyclic alkanes (peoks B and C] and that the gasoline i s highly branched since peak E (CH, groups) is much larger than peak D (aliphatic CH2 or CH). No olefins appear to be present since no resonances appear in region 2. An unpopulated section of the spectrum has been deleted due to space limitations.

2

A

Write for' our latesf Radio Frequency Spectroscopy Bulletin (Vol. 2-*1). Full technical information on both N-M-R and E-P-R .jpectroscopy and the cornplefe "N-M-R of Work" series will' be included. P A L 0

Far further information, circle number '14 A on Readers' Service Card, page 77 A

14 A

ANALYTICAL CHEMSTRY

A L T O

4,

C A L I F O R N I A

Application of the Anthrone Test to Determination of Cellulose Derivatives in Nonaqueous Media

Carbon Replication of Particulates and Ultramicroscopic Crystals Single crystals and particles of colloidal size can be easily carbon-mounted and carbon-replicated. They can then be studied either undissolved or after selective etching. Identification of components of mixtures is possible regardless of recognizable geometry. Much can be deduced by a process of partial etching and stereoscopy. J. H. L. WATSON, Henry Ford Hospital, Detroit 2 , Mich.

Small amounts of cellulose derivatives in oils, fats, and glycols can be estimated by the anthrone test after an' extraction. Ethylcellulose is extracted with a mixed methanol-water solvent zmd cellulose acetate-butyrate with methanol-acetone. E. P. SAMSEL and 1. C. ALDRICK, The Dow Chemical Co., Midland, Mich. Anal. Chem. 29, 574 ( 1 9 5 7 )


Anal. Chem. 29, 562 (1 9 5 7 )

Indirect Photometric Titration of Milligram Quantities of Silver with (Ethylenedinitri1o)tetraaceticacid (It). A Differential Null-Point Method Silver reacts with potassium tetracyanonickelate in ammoniacal solution to release a stoichiometric amount of nickel. The nickel is titrated with EDTA using murexide indicator. A differential null-point method for detecting the end point is simpler, more precise, and allows the determination of smaller amounts of silver than the visual method. S. J. GEDANSKY Syracuse 10, N. Y.

and

LOUIS GORDON,

Syracuse

University,

Complexometric Titrations Following Cupferron Separation of Interferences Thorium, zirconium, and large amounts of iron, which interfere with the titration of divalent metal ions with EDTA, can be rapidly and cleanly removed by one extraction of their cupferron complexes. Extraction is made with a 1 to 1 mixture of benzene and isoamyl alcohol from an acid solution (pH 0.3 to 1.0). J. S. FRITZ, M. J. RICHARD, and A S. BYSTROFF, Iowa State College,

Anal. Chem. 29, 566 (1 9 5 7 )

Amer, Iowa Anal. Chem. 29, 577 (1 9 5 7 )

Effect of Different Carrier Gases on Retention limes in Gas-Adsorption Chromatography Retention times of eluted gases are markedly affected by different carrier ases o n the same column. Carrier gases which are a t o r b e d to some extent reduce the retention time. S. A. GREENE and H. E. ROY, Aeroiet-General Corp., Azura, Calif. Anal. Chem. 29, 569 ( 1 957)

Separation of Bismuth from Uranium Using Thioacetamide Precipitation

Estimation of Melamine in Presence of Guanidine Three methods for the separation of melamine and guanidine are described: (1) precipitation of melamine picrate in acetic acid solution; (;!) precipitation of guanidine picrate in basic solution; and (3) extraction of melamine by boiling 10% sodium hydroxide. R. M. ENGELBRECHT and H. E. MOSELEY, Monaanto Chemical Co.. El Dorado, Ark., W. P. DONAHOC, Monranto Chemical Co., St. Louis, Mo., and W. R. ROLINGSON, Monoanto Chemical Co., Texas City, Tex,

Anal. Chem. 29, 579 (1 9 5 7 )

Thioacetamide precipitation of bismuth sulfide offers a rapid, quantitative method for separation of bismuth from microquantities of uranium. N o uranium is lost. G. A. STONER and H. L. FINSTON, Brookhaven National Lab., Upton, N. Y. Anal. Cham. 29, 570 ( 1 9 5 7 )

Detection of Traces of Iron Colorimetric Determination of Ruthenium Six organic thio compounds which develop colored complexes with the platinum metals have been studied as possible colorimetric reagents for ruthenium. T h e best seems to be s-diphenylthiourea. Foreign metals can interfere.

A 2% solution of 2,2'-bip:rridine or phenanthroline i n concentrated thioglycolic solution will give the characteristic red color of bivalent iron with traces of trivalent iron. T h e test may be used directly for many mineral products as well as for detection of iron in ammoniacal copper solution. For m0.x alloys, mineral acids, and water it is best to collect the iron first o n aluminum hydroxide.

S .B. KNIGHT, R. L. PARKS, 5. C. LEIDT, and K. L. PARKS, University of North Carolina, Chapel Hill, N. C.

FRITZ FEIGL and ALClDES CALDAS, Laboratorio d a Produgdo Mineral, Minirterio d a Agricultum, Rio d e Janeiro, Brazil.

Anal. Chem. 29, 571 ( 1 9 5 7 )

Anal. Chem. 29, 580 (1 9 5 7 )

VOL. 29, NO. 4, APRIL 1957

15 A

Highlights ofthe contributed articles in this issue

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