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ANALYTICAL CHEMISTRY

516 pounds, organic polarographic analysis, polarography in biochemistry a n d medicine, a p p a r a t u s for oscillographic polarogr a p h y , t h e use of oscillographic polarography, a n d kinetics of electrode processes in polarography. T h e s e reviews a r e well written a n d a r e a valuable contribution t o t h e literature. F o r scientists who d o n o t read Czech or Russian these reviews a r e t h e m o s t i m p o r t a n t p a r t of Volume 111. Brief b u t a d e q u a t e reviews in German or English a r e given of 25 originally Czech papers which x e r e presented at t h e congress. Chemical Abstracts has published a b s t r a c t s of all t h e papers i n Volume I and undoubtedly will also m a k e available abstracts of t h e papers i n Volume 111. For this reason t h e complete review papers a r e of m o s t import a n c e t o analytical chemists i n this country w h o a r e indebted t o t h e editor for having m a d e available t h e s e reviews in English or German. Because of t h e presentation of t h e reviews a n d t h e papers i n t h r e e languages, t h e price of t h e volume is high. Readers i n this country will b e impressed with t h e interest shown b y t h e Czech government in this congress. T h e picture of t h e minister of planning appears with t h o s e of H e y r o v s k p Kemula (Warsaw), a n d F u k u t o (chairman of t h e C e n t e r of

Scientific Research a n d Technical Development) o n t h e title page. A photograph of t h e a u t h o r s of t h e reviews is also given. T h e three volumes of t h e congress a r e a n expression of t h e leading role which Heyrovskf a n d his school a r e still playing i n t h e development of polarography. I. RI. KOLTHOFF

Visual Lines for Spectroscopic Analysis. D. M . Smith. 2nd edition. 98 pages. Hilger & Watts, Ltd., London, 1952. Obtainable from Jarrell-Ash Co., 165 Newbury St., Boston, Mass.

Price, $3.25.

T h i s edition is a n amplification a n d a complete revision of t h e first edition, b u t t h e original f o r m of presentation has been v e r y largely retained. Certain sections have been omittede.g., those dealing w i t h t h e detection of metallic impurities in organic precipitates a n d residues a n d in metals. New 'sections include brief notes o n a r c excitation sources a n d d a t a for t h e spectroscopic detection of t h e halogens, selenium, a n d sulfur. Lists of sensitive lines a n d band heads, arranged i n decreasing order of wave length, a r e now given a s a further aid t o t h e a n a l y s t

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy BSTRACTS

of papers presented at t h e Pittsburgh Conference

1 9 on Analytical

Chemistry a n d Applied Spectroscopy, held March 2 to 6, 1953, i n Pittsburgh, Pa., a r e given below. F o r furt h e r information o n individual papers, address t h e a u t h o r s . The Quality of Reagent Chemicals. EDWARD WICHERS, Division of Chemistry, National Bureau of Standards, Washington, D. C. This paper is a discussion of the quality of reagent chemicals based on the analysis and testing of these materials as purchased by the National Bureau of Standards duriug the past 30 years. It is intended to show what may reasonably be expected of reagent chemicals with respect t o the presence of known impurities, the reliability of accepted methods of determining known impurities, the presence of unsuspected impurities, uniformity of composition, and the degree to which the actual composition of substances of reagent quality approaches the nominal (theoretical) composition. Point by Point Chemical Analysis by X-Ray Spectrography. A. GUINIER. ~ N DR. CASTAING, University of Illinois, Urbana, 111.

,4conventional electron microscope was slightly modified to give an electron probe only 1 or 2 microns in diameter. This probe falls on the surface of the specimen, used as a target which emits the characteristic radiations of the elements present in the volume irradiated by the electrons. The x-rays are analyzed by a curved crystal and registered by a Geiger-Miiller counter. The small size of the emitting volume (2-micron area and 1-micron thickness) gives the possibility of analyzing the surface of the specimen point by point. Castaing showed t h a t the analysis could be made quantitative with an accuracy of 1% in most cases. With an x-ray spectrograph in air, it is not possible to detect elements lighter than titanium but with a vacuum spectrograph it is hoped t h a t aluminium can be reached. The minimum account detectable seems to be about 1%. The method is rapid (a few minutes) and nondestructive, and the analysis can be made with the specimen a t elevated temperature. As examples of application, were noted the determination of the composition of the phases of an alloy and the study of intermetallic diffusion. Locating Nonmetal Atoms in Interstitial Alloys. K. H. J A C K , Vestinghouse Electric Corp., East Pittsburgh, Pa. Because of the small x-ray scattering powers of carbon and nitrogen, the direct determination of the locations of these atoms in interstitial alloy structures is facilitated by using crystal-reflected monochromatic radiation, and utilizing the absorption edge effect to decrease the relative scattering power of the metal atoms. Examples of iron and cobalt interstitial alloy structures were described to show

how the x-ray observations are interpreted by various kinds of ordered and disordered arrangements of interstitial atoms. Monochromator techniques are particularly valuable where the interstitial atom concentrations are small. For example, it has been possible t o elucidate the complete sequence of structural changes which occurs ' nitrogen is aged. when iron containing not more than 0.06 weight %

Polarographic and Microcoulometric Determinations with a StaTHOMA5 tionary Mercury-Plated Platinum Electrode. L. B. ROQERB, L. MARPLE,AND KENNETHW. GARDINER, Department of Chemistry and Laboratory of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge 39, Mass. I t was the purpose of the research described to investigate the characteristics of mercury-plated electrodes in an attempt t o extend the range of usefulness of polarographic and coulometric dissolution techniques. The mercury plating of a noble metal provides a stationary deposition surface having the favorable overvoltage characteristics otherwise afforded only by the dropping mercury electrode. The use of such a stationary mercury electrode for polarographic reactions involving a deposition is suitable for quantitative purposes only if the conditions are maintained rigorously constant from run to run. However, conditions for reactions of ions or molecules having soluble products are much less critical. Half-wave potentials for reductions-of organic compounds are usually the same as those obtained with the dropping mercury electrode. The fact t h a t the diffusion currents remained essentially constant with time indicated t h a t the surface was not contaminated and hence might be useful for continuous measurements. This electrode has also been employed successfully in t h e coulometric determination of submicrogram amounts of zinc, cadmium, and mixtures of the two. As a result of the failure of platinum to amalgamatc appreciably with mercury, calibration curves for coulometric determinations remain constant. Amalgamated electrodes, on the other hand, tend to change with time, although the mercury is sufficiently adherent to permit the electrode t o be rotated. Semimicrodetermination of Nitrogen in the Refractory Metals. XARTIN F. QUAELY, Westinghouse Electric Corp., Research Department, Bloomfield, N. J. The determination of relatively small quantities of nonmetallic impurities, such as nitrogen and oxygen, in the refractory metals Mo, Ti, U, T h , V, Zr, W, and Ta, has taken on new importance with the demand for high temperature materials which have superior physical and chemical properties. Procedures for the solution of the metals and their nitrides so as t o release the nitrogen in soluble form have been developed. The effects of various periods of digestion of the samples on the r w o r e r y of nitrogen were discussed.

V O L U M E 2 5 , N O . 3, M A R C H 1 9 5 3 After solution of the sample, the ammonia is distilled off in a n allglass semimicro steam distillation apparatus. The amount of ammonia i n t h e distillate is determined with a spectrophotometer after nesslerization for very small quantities of nitrogen, or by titration with standard acid for larger amounts of nitrogen. The precision of the method was discussed briefly. -4short historical survey of previous work on the determination of nitrogen in metals was given. Determination of Hydrogen i n Steel Forgings by Warm Vacuum Extraction and Mass Spectrometer Analysis. ROBERTM. LOWY, Materials Engineering Chemical Laboratory, Westinghouse Electric Corp., Pittsburgh, Pa. Hydrogen has been found by many investigators t o have detrimental effects upon the physical properties of steel forgings. The hydrogen content of steel varies from less than 0.1 t o about 10.0 p.p.m. A warm vacuum extraction apparatus has been constructed for the evolution and collection of gas, principally hydrogen, from steel in the solid phase. Details of the construction and operation of the apparatus were presented. .I comparison was made of t h e applicability of warm extraction and vacuum fusion methods t o this problem. Included were comparisons of values obtained on duplicate samples, reliability of t h e results and system operation, cost, and construction. Obtaining absolute values of the hydrogen content of steel is difficult by any method because of the problems of securing representative samples, duplicate samples, and standard samples. Methods for sampling steel forgings, storing samples, and preparing them for introduction t o the vacuum system were described. Colorimetric Determination of Small Amounts of Boron in Titanium Alloys. MAURICECODELLAND GEORGENORWITZ,Frankford hrsenal, Philadelphia, Pa. An accurate method was proposed for the colorimetric determination of small amounts of boron (0.0000 t o 0.10%) in titanium alloys. The sample is dissolved in sulfuric acid and the borides are oxidized with hydrogen peroxide. The hydrogen peroxide is destroyed by boiling the solution with an iron salt which acts as a catalyst for the decomposition of the hydrogen peroxide. The boron is distilled as methyl borate and the alcohol removed by adding sodium hydroxide and ammonium hydroxide and evaporating t o dryness. The boron is then determined colorimetrically with dianthramide. Determination of Phosphorus in Titanium Alloys. MAURICE CODELL AND JAMES J. MIKULA, Frankford -4rsena1, Philadelphia, Pa. Phosphorus may be determined in titanium metal by dissolving the sample in platinum ware using a mixture of hydrofluoric and nitric acids, adding sulfuric acid, and heating t o fumes. Sodium fluoride is added in order t o complex titanic ions. After dilution, ammonium molybdate solution and stannous chloride are added and the resulting molybdenum blue color is measured photometrically. Photometric Determination of Columbium Tungsten, and TanJ. LEOMARTIN,A N D talum in Stainless Steels. LUTHERIKENBERRY, W. J. BOYER,Brmco Steel Corp., Middletown, Ohio. The increased use of ferrocolumbium containing appreciable amounts of tant,alum (5 t o 25%) has made it necessary t o determine the tantalum as well as the columbium content of Type 347 stainless steel. These steels often contain varying amounts of tungsten which inadvertently get into the melt with the scrap. The separation of columbium, tungsten, and tantalum as a group by the conventional hydrolysis scheme is readily accomplished. Photometric procedures have been developed for determining these three elements after the group separation. The columbium and tungsten are determined by additive absorbancies utilizing the color reaction with hydroquinone, and the tantalum is determined by utilizing the color reaction with pyrogallic acid. The method was found t o be satisfactory when applied to the mixed oxides of columbium, tungsten, and tantalum after a preliminary group separation. This scheme can also be applied t o the mixed oxides obtained from other materials such as ores and slags. Isolation of Beryllium from Urine. GEORGE A. WELFORD, GEORGE PETERSON, JACK FAST, AND JOHN H. HARLEY, U. S.Atomic Energy Commission, Health and Safety Division, New York, iY.Y .

A procedure was outlined for the isolation of trace quantities of beryllium from urine employing an anion exchange resin. Beryllium is precipitated from the aliquot of urine using aluminum as a carrier partially t o separate the excess salts and organic matter. Sodium hydroxide is added t o convert existing beryllium t o the beryllate anion. Other precipitable materials are partially kept in solution with Yersene (tetrasodium salt of ethylenediaminetetraacetic acid). The anion is exchanged on the hydroxide form of IR4B resin batch-

517 wise, and eluted with 6 .?T hydrochloric acid. Calcium, magnesium, phosphates, and other interfering materials are not exchanged on the resin. The resulting solution may be analyzed spectrographically or fluorophotometrically. Determination of Titanium Applicable to Ferrotitanium, Ilmenite, Rutile, and Titanium-Bearing Slags. E. E. BROIW, Vanadium Corp. of America, Bridgeville, Pa.

A 0.50- to 1.00-gram sample is fused in an iron crucible with sodium peroxide, melt leached in water, boiled, and centrifuged. Supernatant liquor is decanted and discarded. This eliminates chrome and vanadium, if present. The precipitate is dissolved in sulfuric acid. Liquid zinc amalgam is added and the titanium solution is reduced by a mechanical tumbler or can be agitated by hand. The zinc amalgam is parted from reduced solution by the addition of carbon tetrachloride. Carbon dioxide is passed through the upper layer to maintain an inert atmosphere and t o stir the solution. Potassium thiocyanate is added. The reduced titanium is oxidized by a standard solution of ferric ammonium sulfate. After the sample is centrifuged, the test is completed in the same bottle. This is a great economy of time and labor, as there is no need for filtration or washing. Determination of Ascorbic Acid by a New Colorimetric Reaction. MORTON SCHMALL, c. Br. PIFER,AND E. G. WOLLISH,Products Control Laboratory, Hoffmann-La Roche, Inc., Nutley, N. J. Most methods used a t present for the colorimctric determination of ascorbic acid are based on the reduction of dichlorophenol indophenol or the condensation of dehydroascorbic acid with 2,Cdinitrophenylhydrazine. A new reaction for vitamin C was described, involving the coupling with a diazotized aromatic amine in acid medium, followed by development of a stable blue color in alkaline solution. This dye, with a maximum absorbancy a t 580 mp is compared with standards in a suitable colorimeter. Samples containing as little as 10 micrograms of ascorbic acid per milliliter can he determined. The method is highly specific for the determination of vitamin C in the presence of dehydroascorbic acid and all other vitamins normally found in pharmaceutical preparations. The method has been found useful for the assay of multivitamin preparations, such as tablets, liquids, and parenteral solutions. Its application for the determination of vitamin C in fruit juices and processed foods as well as biological liquids was discussed. The simplicity of the procedure permits rapid anal able for routine control. Application of Fluorimetry to Hormone Assay. H . S. STRICKLER, M. R. STEAR,R. C. GRAUER,ASD mILLI.4M H. SINGER,Memorial Research Laboratory, Allegheny General Hospital, Pittsburgh, Pa. This application is a t present limited to adrenalin and the steroidal hormones, which comprise the adrenocortical and sex hormones. Qualitative application of fluorimetry to steroids was early made by Cuboni, who observed fluorescence of pregnancy urine on treatment with concentrated sulfuric acid. Analysis of pure products is comparatively simple, but interest is mostly in product of steroidal metabolism in urine, etc., where impurities complicate assay greatly. The present work was done with a sensitive fluorimeter with quartz optics, equipped with combinations of glass and interference filters. I n the later part of the work preliminary purification included countercurrent distribution (ccd). Proper conditions for analysis include low concentration of foreign pigment to avoid absorption, low concentration of hormone to avoid self-quenching by collisions of the second kind, and purification t o lower quenching by foreign moleculea. Partial quenching by impurities appears t o be the greatest source of error with the estrogens, which were studied most intensively. Correction schemes will be Jhown and maps of ccd separations assayed using different filter combinations (exertation 435 and 365 mp; phototube 490 and 524 mp). Direct Determination of Zinc by Dithizone in a Water-Glycol System. BERT L. VALLEE,Department of Biology, Massachusetts Institute of Technology, Cambridge, Mass. The extraction of zinc dithizonate into carbon tetrachloride or chloroform has been the standard procedure for the colorimetric determination of zinc in the past. Extraction procedures are tedious, lengthy, and subject to considerable error. The present method avoids these objectionable features. Instead, it utilizes the monomethyl ether of ethylene glycol (methyl Cellosolve) as a solvent for dithizone. This solvent with the dissolved dithizone i j watermiscible. rl method for the determination of zinc in water-methyl Cellosolve mixtures was worked out. I t is sensitive a n d precise. The details of the procedure were presentecl.

ANALYTICAL CHEMISTRY Ultraviolet Spectrophotometric Determination of Antimony. ANITAELKIND, K. H. GAYER, AXD D . F. BOLTZ,Wayne University, Detroit, Mich.

now commercially available, were presented. An outline of t h e basic circuit and t h e range and limits of application were discussed.

A spectrophotometric study has been made of iodoantimonious acid which was found to exhibit an absorbancy maximum in t h e ultraviolet region in addition t o its absorbancy maximum in t h e visible region. Conformity t o Beer's law was observed a t 330 and 425 mp. T h e optimum concentration range was found t o be 3 to 25 p.p.m. antimony in the visible region and 0.3 t o 4 p.p.m. antimony in t h e ultraviolet region when I-cm. absorption cells were used. T h e sensitivity of t h e iodoantimonious acid method is increased approximately 750% by using the proposed ultraviolet method. T h e effect of 25 diverse ions was determined for t h e ultraviolet and visible methods. Bismuthyl, plumbous, and mercuric ions interfere. The effect of other solution variables was discussed and a general procedure was outlined.

Colorimetric Determination of Zirconium in t h e Presence of Uranium. WILLIAMH. OWENSAND HARRY G. KING, Carbide and Carbon Chemicals Division, Union Carbide and Carbon Corp., Oak Ridge, Tenn.

Gasometric Method for the Determination of Hydrogen in Carbon. W. G. GULDNERAND A. L. BEACH,Bell Telephone Laboratories, Murray Hill, N. J. An apparatus was described which is capable of extending t h e precision for the determination of hydrogen in carbon. Normally, these determinations are carried out by some modification of t h e Pregl technique. I n this method, approximately 100 mg. samples are weighed into platinum bags, sealed into the borosilic glass apparatus, and evacuated. Each sample bag, in turn, is injected into a platinum crucible which is heated by high frequency induction. T h e carbon is burned in a low pressure flow system and the hydrogen is converted t o water vapor. T h e water vapor is measured in the gas phase by means of a closed-end mercury manometer.

Radioactivation Study of the Contribution of Impurities by Graphite Crucibles. GEORGEH . MORRISONAND RICHARDL. RL-PP, Sylvania Electric Products, Inc., Flushing, N. Y.

Potentiometric Differentiation of Inorganic Cations. C. W. PIFER,MORTONSCHMALL, .4ND E . G . WOLLISH,Products Control Laboratory, Hoffmann-La Roche, Inc., Nutley, N. J. Although many inorganic cations can be titrated individually as bases, no potentiometric method had been available for a differential titration of two or more cations of varied basic strength. A method was presented using a nonaqueous solvent mixture for solubilizing t h e acetates of monovalent and divalent cations. Depending upon t h e difference of t h e mobility of t h e inorganic cations, it was possible t o titrate potentiometrically mixtures of two or three cations, such a s sodium, potassium, ammonium, barium, calcium, magnesium, etc., using 0.01 N perchloric acid in p-dioxane as titrant. This terhnique permits postulation of the relative degreee of basic strength for a number of cations.

An examination of t h e fluorescence of samarium(II1) in solid alkaline earth tungstates and molybdates which have been reported in t h e literature t o be suitable base materials for samarium(II1) fluorophors showed calcium tungstate t o be t h e most promising for analytical purposes. T h e wave lengths and relative intensities of t h e 14 bands comprising t h e visible fluorescence of samarium(II1) in calcium tungstate were determined spectrographically, as were variations due t o t h e method of preparation of the fluorophor, to the exciting radiation (Hg 2536 A. or Hg 3650 A,), and t o t h e temperature of t h e fluorophor during excitation. Conditions for obtaining maximum intensity of samarium(II1) fluorescence were: (1) ignition of an evaporated slurry of calcium tungstate and samarium(II1) solution a t 200' t o 400' C. for 15 minutes, then a t 400° C. for 15 minutes; (2)excitation with H g 2536A. a t a fluorophor temperature of 100' C. Under these conditions. t h e lower limit of detection obtained with a grating spectograph having photomultiplier reception was 0.057 of samarium(II1) in 25 mg. of calcium tungstate: with a filter fluorophotometer, also having photomultiplier reception. 0.27 of mnarium(II1) in a 25 mg. of calcium tungstate.

An adaptation of t h e alizarin lake method for determining zirconium in t h e presence of uranium was presented. T h e method depends largely upon t h e purification procedure, which assures t h e removal of common interferences. Fluoride and phosphate are removed by volatilization, and sulfate effect is eliminated by t h e addition of calcium chloride. Uranium is oxidized t o U('I), and does not interfere at the wave length utilized. Impure solutions may be analyzed rapidly with precision and accuracy of within 120%.

T h e electrical behavior of semiconductor materials is greatly dependent upon the presence or absence of extremely small amounts of impurities. I n t h e case of germanium, used in t h e transistor, it is important t o determine quantitatively 1 part of impurity in 100,000,000 parts of germanium. One of t h e few analytical techniques operative in this concentration range is radioactivation analysis. T h e present investigation is concerned with a study of t h e contribution of trace amounts of impurities by highly pure graphite boats and crucibles t o germanium during a melting process. Graphite mith a n ash content less t h a n 0.01% was irradiated with neutrons in a nuclear reactor; t h e radioactive boat was then used in t h e melting process. Analytical Aspects of the Reactions of 2-(Alpha-Pyridyl) -benzimidChemical separations and standard radiochemical techniques were azole with Metallic Cations. JOSEPH WALTERAND H. FREISER, then utilized t o identify and estimate t h e induced radioisotopic imChemistry Department, University of Pittsburgh, Pittsburgh, Pa. purities. T h e compound, 2-(alpha-pyridyl)-benzimidazole,was found to reDichromate Oxidation of Diethylene Glycol. MARIOJ. CARDONE act with several metallic ions including iron(II), iron(III), copper(I), AND JOHN W. COMPTON, Wyandotte Chemicals Corp.. Wyandotte, oopper(II), cobalt(II), and mercury(I1). With all these ions except Mich. mercury, the reagent gave color reactions. Most notable was t h a t with iron(I1) with which a deep red colored complex was formed. An oxidation method for resolving organic mixtures containing This complex, studied spectrophotometrically, was found t o have a nonvicinal hydroxyl and/or ethereal oxygen such as glycol mixtures maximum absorption at 490 m p (mole extinction coefficient = 7800). requires a strong oxidant acting differentially. T h e behavior of Maximum color development was obtained a t a reagent t o metal dichromate as a differential oxidant is indicated by a study of the mole ratio of 6 and a t a p H of 5.7. T h e complex, which could be ex1iterat.ure. tracted by chloroform, was shown to function as an acid-baseindicator. Oxidation of diethylene glycol by dichromate in sulfuric acid bolution a t 100' C. results in three well-defined stages or levels of oxidaSpectrophotometric Determination of Aluminum in Thorium, tion indicative of definite stoichiometric reaction mechanisms. These D . W. MARQERUM, WILBURSPRAIN,AND C. V. BANKS,Ames Laboralevels are attained in solutions which are 50, 25, and 12.5% by volume tory, Atomic Energy Commission, Iowa State College, Ames, Iowa. in sulfuric acid and are independent of t h e glycol and dichromate T h e preparation of highly pure thorium metal has necessitated concentrations, provided t h a t a moderate excess of dichromate over accurate methods for the determination of trace impurities of common t h a t stoichiometrically required for t h e oxidation of t h e glycol t o t h e metals such as aluminum. While this m a y often be accomplished respective level is provided. dpplication of the differential oxidation spectrographically, wet chemical methods are advantageous because method for the resolution of t h e binary mixture, diethylene glycol. of their greater accuracy and in some cases their simplicity. A rapid and ethylene glycol was successful over a limited composition range and sensitive chemical procedure has been devised for the deterwith an accuracy of +5% of t h e respect,ive glycol content. mination of trace quantities of aluminum in thorium. This procedure T h e accuracy limitation was due t o the lack of differential oxidation utilizes a spectrophotometric determination of aluminum following behavior of ethylene glycol under t h e conditions coupled with the a n extraction with a solution of 8-quinolinol in chloroform. Extracrelatively small oxidation level change of the diethylene glycol. tion of thorium is prevented by the use of either 4-sulfobenzene-arsonic Further study providing additional data on t h e dichromate oxidation acid or concentrated acetate buffer as the masking agent. From 2 t o characteristics of these and other organic compounds should result 1207 of aluminum may be determined to within iZO.57. T h e in considerable improvement of t h e differential oxidation method. method can easily be extended for greater amounts of aluminum. Extraction with 8-quinolinol in chloroform from a n acetate-acetic Analytical Studies of the Fluorescence of Samarium in Calcium acid buffer results in removal of acetic acid into t h e chloroform phase Tungstate. C. GORDON PEATTIE AND L. B. ROGERS, Department of causing partial ionization of t h e 8-quinolinol. Absorption spectra for Chemistry and Laboratory of Nuclear Science and Engineering. a 1% solution of 8-quinolinol in chloroform with acetic acid are given. Massachusetts Institute of Technology, Cambridge, Mass.

Controlled Potential Electro-Analyzer. J. D. BODE,9.W.LEVISE, R . IT. KRERS,Fisher Scientific Co., Pittsburgh, P a . T h e application, design, and operation of an electroanalyser with electronically controlled electrode potential, t h e only such instrument

AND

V O L U M E 25, NO. 3, M A R C H 1 9 5 3 An essentially linear relationship between intensity of fluorescence and samarium(II1) content was found over t h e concentration range, 0.5 t o 907 of samarium(II1) in 25 mg. of calcium tungstate for both excit,ing radiat,ions. For three different samples of t h e same samarium(II1) concentration, excited by H g 2536 il., t h e average variation in intensity of samarium bands was 10%. T h e average variation was reduced t o 5% b y employing a n internal standard procedure which took advantage of t h e noninterference of t h e fluorescence of t h e rnniarium(II1) in t h e yellow t o red portion of t h e spectrum with t h a t of the calcium tungstate in t h e blue. T h e fact t h a t t h e samarium(111)fluorescence was not excited directly b y H g 2536 A. b u t by transfer of absorbed energy from excited tungstate groups t o samariuni(111) ions, accounted for t h e high sensitivity of t h e samarium(II1) fluorescence t o interference b y europium, gadolinium, and neodymium. d related system, made by incorporating samarium(II1) into calcium tungstate containing 10% lead t u n g s h t e , had a samarium(II1I fluorescence as much a s 50% more intense t h a n t h a t obtained when calcium tungstate alone was used as t h e base material. Although studied in less detail, its behavior appeared t o be very similar to t h a t of t h e system, calcium tungstate-samarium(III), except t h a t t h e intensity of samariuni(II1) fluorescence failed to increase with t h e temperature of t h e fluorophor. Analytical Studies of t h e Fluorescence of Samarium in Calcium Sulfate. C. GORDONPEATTIE A N D L. B. ROGERS,Department of Chemistry and Laboratory of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Mass.

-1spectrographic investigation parallel t o t h a t reported earlier for .vamarium(III) in solid calcium tungstate has been made of t h e fluorescence of samarium in those solid alkaline earth carbonates. fluorides, and sulfates which have been reported in t h e literature t o be suitable base materials. As a result, calcium sulfate was chosen as the most suitable base material for analytical purposes. I n addition to studying t h e variables of t h e exciting wave length (Hg 2536 ii.or H g 3650 11.)and t h e temperature of t h e fluorophor, t h e effect of a change in t h e valence of t h e samarium from (111) t o (11) was also evaluated. T h e calcium sulfatesamarium(II1) fluorophors were prepared by coprecipitation of samarium(II1) with calcium sulfate, followed by ignition a t 850° C . for 15 minutes. T h e product was not fluorescent under H g 2636 A. excitation, but irradiation with H g 3650 A. produced a red fluorescence consisting of nine bands which mas uiiaffected hy increasing t h e temperature of t h e fluorophor t o 100' C. T h e lower limit of detection of samariuni(II1) in this system was sonren-hat lei.+ t h a n 157 of samarium(II1) in 100 mg. of calcium sulfate. Bombardment, of this calcium sulfate-samarium(II1) fluorophor with 3 m.e.r. electrons. produced in a Van d e Graaf generator, gave a liniinorphor having only a very weak yellon- fluorescence under H g 2530 A . excitation but a brilliant red fluorescence under H g 3650 .I. excitation. T h e spectrum of this red fluorescence consisted of a featureless, triangular-shaped band having a maximum of 6178 + 4 A. T h e intensity of this band almost doubled on heating t h e fluorophor t o 00' C. hut heating t o 100' C. produced no significant increase in intensity over t h a t of 60' C. Measurements made with both a spectrograph and a filter fluorophotometer showcd a lower limit of detection of about 10-47 of samarium(II1) and a linear increase in the fluorescence with t h e initial concentration of samarium(II1) in t h e $elution of t h e sa.mple over the range, 0.001 t o 1557 of samarium(II1). The average deviation obtained was 10%. A sixfold excess of europium, gadolinium, or neodymium produced no measurable effect O I L t h e intensity of t,he samarium(I1) fluorescence. I n t h e case of europium, t h e presence of a strong band a t 3857 A. due t o europium(I1) diould permit t h e simultaneous determination of samariumiI1) arid ruropium(I1). Precipitation of Iodates from Homogeneous Solution. Separation of Thorium Iodate. C. RICHARD STINE. ~ N D LOC-ISGORDON,Syracuse University, Syracuse, N. Y. T h e precipitation of throium iodate in strong nitric acid solution affords a separation from many interfering elements. This separation has been utilized for several years in a method for t h e precipitation of thorium in t h e presence of t h e trivalent rare eaiths and phosphate in monazite sand. A gelatinous and voluminous precipitate of thoi.ium iodate is obtained. Thorium iodat,e may be precipitated from homogeneous solution in a dense and granular form with iodate produced by t h e reduction of periodate with ethylene glycol; t h e latter is slowly produced by t h e hydrolysis of beta-hydroxyethyl acetate. T h e precipitate thus obtained is easily washed and filtered. With a single precipitation less contamination is encountered than in t h e conventional heterogeneous method. Upon double precipitation, this method effects quantitat i r e separation of thorium from large amounts of rare earths and phosphate. Owing t o this increased efficiency of separation, a more rapid and

519 accurate procedure is possible for t h e determination of thorium in monazite sand. Other insoluble iodates m a y be similarly precipitated from homogeneous solution. Analysis of Radionuclide Mixtures Using a Gamma-Beta ScintilASD M. B. LEBOEUF, General lation Spectrometer. R. E. COSNALLY Electric Co., Nucleonics Department, Richland, Wash. Beta and gamma scintillation detectors have been designed for use with an automatic recording energy spectrometer. T h e application of this instrument t o t h e analysis of mixtures of radionuclides which decay by gamma emission has been investigated. Integration of t h e area under t h e photoelectric peak of a differential pulse height scan obtained with t h e gamma energy spectrometer permits quantitative determination of each gamma emitter present. Using this instrument, t h e substances present in three component mixtures have been identified, and t h e compositions of t h e mixtures have been determined v i t h a precision of 5 2 . 6 % (std. dev.) of the total gamma activity. Analyses of solutions containing mixed gamma emitters were performed directly, without preliminary separations, in less t h a n 4 0 minutes. It is believed t h a t this instrumental method for t h e analysis of radionuclide mixtures will he of particular value t o radiochemi(,a1 process control because of its speed and reliability; in addition, i t is expected t o find application in a n y studies where mixed gamma emitters are used. Dielectric Constant for the Dioxane-Water System from Z O O t o c. FR.4NK E. CRITCHFIELD, JOHNh.GIBSON,.JR., A H D JAMES L. HALL,Department of Chemi-try, West Virginia University, Morgantown, W.Ta. 35'

The dielectric constant of t h e system dioxane-water has been measured as a function of composition a t t h e temperatures 20°, 25O, 30°, and 35' C. B y reference t o these data t h e composition of dioxanen-ater mixtures of known dielectric constant may be determined urately. T h e measurements reported here are an outgrowth of an attempt t o duplicate t h e existing dielectric constant data for this system. An improved design of a noninductive type of dielectric constant cell, especially suited for high-frequency measurements was rbcribed. Determination of Tin and Chromium in Zirconium Binary Alloys. ~ V I L L I A M9.DUPRAW, Armour Research Foundation, Illinois In>titUte of Technology, Chicago. Ill. Dissolution of t h e zirconium binary alloys is accomplished by utilizing a dilute niixture of fluohoric and sulfuric acids. Tin or chromium is subsequently determined by coiiventional analytical procedures. T h e methods are quite fast and are accurate. Recovery data are given for 1.6 t o 66.0% alloying ronstituent. Determination of Low Concentrations of Copper. J. KENNETH C. COSSELL.K. H . & L. D. Bets, Philadelphia, RROWX. ~ N DJAMES Pa. Low concentrations of copper (0 t o 0.5 p.p.m.) have been deterriiiried in the past by the use of dithiaone, which is extremely sensitive hut has t h e disadvantage t h a t a number of ions interfere and must either be absent or be removed by extra steps in t h e procedure. T h e deep color of t h e dye itself i.7 another disadvantage when used with phritometers. Diethyldithiocarbamate has also been used but is not as sensitive as dithizone and a number of ions interfere in relatirely low concentration. Seo-cuproine (2,9-diinethyl-l.lO-phenanthroline) , a new copper ipecific, is much superior to tiithizone and diethyldithiocarbamate, .since it has little color itself and almost n o interferences from other ions. This new dye was described by Smith and McCurdy in the and a test procedure February issue of . ~ N A L Y T I C \ L CHEMISTRY described which g a w copper concentrations in t h e range of 0 t o 11 p.p.ni. Their procedure c,alled for two extractions with 10 ml. of distilled isoamyl alcohol and suhiequeiit dilution of t h e solvent to 50ml. total volume before the optical denshy was measured in a Model 11 Cary recording spectrophotometer. I n t h e present procedure. 100 ml. of sample buffered to pH 4.2 is extracted once with 10 ml. of ethylene dichloride containing t h e neocuproine. T h e ethylene dichloi,ide is drawn off and 0.5 ml. of isopropyl alcohol added t o clarify t h e solution. T h e solvent is then measured in a Model DU Beckrnan spectrophotometer and t h e optical density read a t 454 mp. T h e spectrophotometer gives a straight line when parts per million c'opper is plotted against optical density. K i t h care 0.001 p.p.m. copper ?an he determined. Colorimetric Determination of Copper with Neo-Cuproine. Arnold R . Gahler, Union Carbide and Carbon Research Laboratories, Inc., Xiagara Falls, New York

A study has been made of the accuracy and precision of t h e colorimetrir determination of copper in ferrous alloys and miscellaneous

ANALYTICAL CHEMISTRY materials by the extraction of t h e copper 2,9-diniethyl-l,lO-phenanthroline (neo-cuproine) complex with a chloroform-ethanol solution. Determination of Traces of Oxygen in Helium. LEONARDP. PEPKOWITZ AND EDWIN L. SHIRLEY, General Electric Co., Knolls Atomic Power Laboratory, Schenectady, N. Y . Because of t h e extreme requirements in regard t o t h e oxygen content of the inert gas blankets for liquid metal work, it is necessary to have a precise and sensitive method for measuring oxygen concentrations in t h e range of 0 t o 50 p.p.m. A batch method has been developed based on t h e Winkler manganous hydroxide reaction which provides t h e required sensitivity and precision. As little as 1 p.p.m. can be detected with a n average deviation in t h e 0 t o 25 p.p.m. range of i0.6 p.p.m. Bo blank is detectable because t h e method eliminates t h e sources of error such a s M n + + +in t h e manganese hydroxide which reacts as oxygen in t h e usual manganese hydroxide procedure and gives rise t o a high positive blank value. Relatively small samples can be handled since t h e reactions can take place below atmospheric pressure. This fact eliminates t h e need for a carrier gas, thus removing one of t h e contaminating sources of error.

tion gave an average value for each K a of the diprotonated base of 3.2 x 10-4. Utilization of this value in conjunction with equilibrium measurements made on t h e complex in acid solutions gave a value for t h e dissociation constant of Fe(terpy)z+ +F e f 2 2 terpy of 1 X lo-’*. This is t h e first record of measurements of the formal potential of t h e system, t h e base strength, and t h e stability. It is particularly interesting a s an example of a chelate complex involving a tridentate group which can accept only two protons.

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Polarography with Polarized Mercury Pool Electrodes. CARLA. STREULIAND W. DONALDCOOKE,Baker Laboratory, Cornel1 University, Ithaca, New York.

I n t h e application of polarography t o extremely dilute solutions the dropping mercury electrode has inherent difficulties which must he overcome. T h e small area of t h e drop yields diffusion currents of a low order of magnitude and t h e high charging current limits the scope of the method. -4large polarized mercury pool contained in a DesJicoated vessel, has been applied t o t h e polarographic analysis of low levels of concentration. I n contrast t o the dropping mercury electrode the area of t h e pool can be varied over a wide range and t h e charging current density is much smaller. Polarograms obtained Spectrophotometric Determination of Cobalt with 2-Nitroso-lwith such apparatus are similar in nature to those obtained by oscilloNaphthol-4-Sulfonic Acid. ~ \ - A R R E N m’. BR.4NDT A N D WARREN&!Igraphic . methods. T h e peaks obtained are linear with concentration WISE,Department of Chemistry, Purdue University, Lafayette, Ind. and t h e curves in many cases are thermodynamically predictable. T h e method has been applied t o bismuth, copper, chromium, lead, T h e investigation was undertaken in order t o determine whether thallium, and zinc in the parts per billion range. t h e known reaction of cobalt with 2-nitroso-1-naphthol-4-sulfonic acid offered any advantages for the spectrophotometric determinations of t h e metal. T h e reagent is readily prepared by published Detection of Atoms and Free Radicals in Flames by Mass techniques. I t is easily purified and dissolves in water to g i w a yelApplied Physics LaboraSpectrometric Techniques. S. N . FONER, tory, Johns Hopkins University, Silver Spring, Md. low solution. T h e color reaction of cobaltous ion with t h e reagent was studied at Combustion proceeds as a chain reaction involving a number of various p H values. A constant absorbance is obtained from p H 6 to highly active intermediates. T h e identification of these intermedi10 in t h e presence of a 4 t o 1 or greater reagent t o metal ratio. T h e ates is essential to t h e establishment of t h e chemical mechanisms invalidity of Beer’s law was verified in t h e concentration range of 4 X volved. T h e detection of atoms and free radicals in flames by mass t o 1.25 X 10 M cobalt a t pH 7. I n all cases a n equal concenspectrometry requires a special gas sampling system. I n the experitration of t h e reagent was used as a blank. ments described, molecular-beam techniques are used t o transport the T h e colored system is stable a t p H 7 for three months. Ordinary gas from t h e flame t o t h e ion source of the mass spectrometer. Backtemperature changes are without effect. Several ions interfere to ground contamination has been virtually eliminated by mechanically various degrees. Nickel was removed by precipitation with dimethylchopping t h e molecular beam and employing phase detection of t h e glyoxime and t h e remaining soluble cobalt complex destroyed by ion signal. T h e application of these techniques was illustrated by boiling with concentrated sulfuric acid. Iron and copper interfere, examples of low pressure flames. -4mong t h e species which have been but this interference can be prevented by the use of citrate ion. This definitely identified in flames are H , 0, OH, CH8. The mass specwill permit accurate determinations of cobalt in t h e presence of 20 trum obtained for a simple hydrocarbon flame, such as the CHI-0% times as much iron and copper as there is cobalt in t h e solution. flame, is extremely complicated. T h e analysis of the products is T h e method is a convenient, very sensitive and stable one for derendered difficult because there are a large number of components termining cobalt. As such it offers definite advantages over existing present and some of t h e peaks may correspond to unstable constitumethods, particuarly when large amounts of nickel are not present. ents whose mass spectra are not known. Some remarks were made on current experiments which are designed t o follow in detail some Determination of Carbon in Sodium and Sodium-Potassium simple gas phase reactions. Alloy. LEONARD P. PEPKOWITZ A N D RAYMOND J. DOWXER,General Electric Co., Knolls Atomic Power Laboratory, Schenectady, N.Y. Some Ions of High Kinetic Energy in Mass Spectra of Polyatomic 9 wet combustion-conductometric method for t h e determination of Molecules. FREDL. MOHLER,VERNOKH . DIBELER,ASD R . 11. carbon in sodium and N a K is described. I n order to have a n amenREESE,National Bureau of Standards, Washington, D. C. able compound for t h e wet oxidation, t h e sodium or N a K is converted When t h e low mass peaks of hydrocarbons are satellite recorded t o t h e respective chromates in a carbon dioxide-free atmosphere. with low ion accelerating voltage, one observes satellite peaks on t h e T h e relatively simple apparatus is provided with a preliminary high mass side of t h e main peaks and these come from ions with a absorber t o eliminate t h e troublesome effect of sulfur trioxide refairly homogeneous high kinetic energy. Observations of t h e satellite leased during t h e oxidation. peaks of CHs+ ions for 13 hydrocarbons and CH3CFa were reported. The conductometric cell has been drastically simplified compared These ions have kinetic energies ranging from 1.5 to 3.4 e.v. Relat o the devices described in t h e current literature. tive intensities have a wide range of values, hut the high kinetic energy As little as 10 micrograms of carbon can be measured by this techpeak is smaller t h a n t h e zero energy peak except in benzene. T h e nique. On 1-gram samples a n average mean deviation of i O . O O l % appearance potential of t h e high energy peak is roughly 30 volts and carbon has been obtained with brick sodium. a t 20 volts only t h e low energy peak is observed. These high energy peaks are ascribed t o ions arising from t h e dissociation of doubly Iron-Z,Z’,Z”-Tripyridine System. WARREN W. BRANDT. ~ N D charged molecules and it is shown t h a t t h e observed kinetic energy JACKP. WRIGHT,Department of Chemistry, Purdue University s roughly equal t o t h e computed Coulomb energy of two charges a t Lafayette, I n d . t h e maximum distance possible in the molecule concerned. T h e purple complex of ferrous iron with 2,2’,2”-tripyridine is used regularly for t h e colorimetric estimation of iron. However, a deFormation of Negative Ions of Sulfur Hexafluoride. A. J. tailed study of t h e system has not been reported. This investigation AHEARNAND N. B . HAXNAY, Bell Telephone Laboratories, Murray was undertaken t o establish the oxidation-reduction potential of t h e Hill, N . J. system and t o determine t h e stability of t h e complex. T h e formal oxidation-reduction potential was measured by means Kegative ion production in SFs has been studied in a mass spectromof potentiometric titrations. T h e value in 0.1 N sulfuric acid is eter; SFs-, SFa-, Fz-, and F- were identified. T h e SFs- and SFj1.10 i 0.01 volts. T h e oxidized complex is green or yellow, dependare produced in very large quantities by a resonance capture process ing upon t h e acidity of t h e solution. a t an electron energy of about 2 e.v. and are formed in approximately I n order t o determine t h e stability of the complex by equilibrium equal amounts. measurements, it was necessary t o determine t h e basic strength of At higher electron energies, t h e same capture occurs by a secondary t h e 2,2’,2”-tripyridine. T h e evidence shows t h e 2,2’,2’’-tripyridine process, in which low energy electrons released by other excitation funct.ions a s a diacid base in both aqueous and nonaqueous media. and ionization processes suffer t h e resonance capture. Both conductometric and potentiometric titrations gave only one Partial dissociation after electron capture accounts for t h e appearance of F- and Fz- ions below 16 e.v. Above this energy. other inflection point corresponding t o two hydrogen ions per molecule of 2,2‘,2”-tripyridine. T h e potentiometric titration in aqueous soluprocesses will also produce these ions.

V O L U M E 2 5 , NO. 3, M A R C H 1 9 5 3 Possibie explanations of the primary resonance capture mechanism were discussed. Half-Life of Negative Metastable Ions. €3. L. DONNALLY AXD H. E. CARR,Alabama Polytechnic Institute. Negative metastable ions have been detected with a mass spectrometer during an electron bombardment study of ethyl dichlorophosphate [Phys. Rev., 87, l i 0 (1952)]. T h e half-lives of two of these ions have been measured using the method proposed by Hipple [Phus. Rev., 71, 594 (194i)l. Measurements on the metastable ions in the transitions C2HaPOzClz- -+. POzC1- 4- CzHsCl and POzCl-+ C1PO? give 1.9 X 10-6 and 4.8 X lo-' second, respectively, as their half-lives. These values are near t o those given by Hipple for positive metastable ions.

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Ionization and Dissociation by Electron Impact : 1-Butanethiol, 2-Butanethiol, and 2-Methyl-2-Propanethiol. G. L. COOK AND J. V. WALSH,Bureau of Mines, Oil-Shale Research Branch, Laramie, m-yo. Ion appearance potentials for the major ions in the mass spectra of 1-butanethiol, 2-butanethiol, and 2-methyl-2-propanethiol have been determined using a Consolidated Engineering Corp. mass spectrometer, Model 21-103 (modified). By treating t h e ion appearance potentials as heats of formation, bond strengths, have been calculated. Reaction mechanisms and ion structures have been postulated. Studies of this type have been used successfully t o obtain a better understanding of the forces within t h e hydrocarbon-type molecule. However, the literature contains very little information of this type for sulfur compounds. Since there is a rising interest in the sulfur-containing molecule, brought about principally by the increasing use of high-sulfur crude oils, research of this type seems both timely and desirable. Mass Spectrometer Investigation of Higher Valence Uranium Compounds i n UF4. RUSSELLBALDOCK, JOHN R . SITES, L . 0 . GILPATRICK, . ~ N DH . E. C A R ROak , Ridge National Laboratory, Oak Ridge, Tenn.

9time integration method has been developed for the investigation of the contamination of uranium tetrafluoride by higher valence compounds of uranium. D a t a are collected from a sample held a t constant temperature until the sample is completely used up. The origin and measure of UFs were discussed. Combined Method for the Determination of Carbon and Sulfur in Steel. ALBERTC. H O L L E RA N D ROSEMARY KLINKEXBERG, Twin City Testing and Engineering Laboratory, St. Paul, Minn., A N D W. K. AITES,Westinghouse -4ir Brake Co., Wilmerding, Pa. 9 method for the simultaneous determination of carbon and sulfur ill steel was described. The ignition of the sample is carried out in a

Lindberg high frequency combustion furnace. The gases from the combustion of t h e steel in oxygen are passed through a closed syhtem; absorbing first t h e sulfur dioxide in an absorption-titration vessel containing 3% hydrogen peroxide or absorbing thesulfur dioxide in 1.57, hydrochloric acid as in the iodate method, and finally absorbing the carbon dioxide with .iscarite after removal of the moisture from the gases. Many Bureau of Standards standard steels were run by the method. The average per cent deviation for t h e carbon values was 1 0 . 0 0 4 and that for the sulfur values WSLS f 0 . 0 0 2 . Copper(I1)-Dithizone Equilibria in Water-Carbon Tetrachloride.

R.R. GEIGER.4ND E. B. SANDELL, University of Minnesota, Minneapolis, Minn. In order to put the photometric determination of copper with dithizone on a less empirical basis than exists a t present, a detailed investigation has been made of t h e equilibria in t h e system copper(I1)dithiazone-water-carbon tetrachloride. Values are reported for t h e yarious equilibrium constants, including those for the extraction of primary and secondary cupric dithizonates and t h a t for the equilibrium among dithizone and the primary and secondary copper dithizonates in carbon tetrachloride. Observations have been made on the rate of extraction of copper dithizonate as a function of acidity and concentration of dithizone. Solids in Boiler Water by Anion Exchange.

H . hf. RIVERS. ~ X D

T. M. MaRcY, Hall Laboratories, Inc., Pittsburgh, P a .

Solids in a boiler water should be held below a maximum concentration t o minimize carry-over in the steam and t o reduce scale and sludge in the boiler. Because of its rapidity, the conductometric method has largely displaced the gravimetric method as a plant control test. A new test, comparable in accuracy and simplicity to t h e conductonietric method, was described. The boiler water is mixed with a

521 strongly alkaiine anion exchange resin. .In aliqnot of the resultant solution is titrated with a standard acid t o t,he phenolphthalein end point. Since for every milliequivalent of salt i l l the sample a milliequivalent of hydroxide is formed, the volume of standard acid required, multiplied by a suitable factor. is an accurate measure of solids in the boiler water. The influence of compo$ition of sample, weight of resin t o volume of sample, and contact time between resin and sample was illustrated. Comparative results between gravimetric, caonductometric, and anion exchange methods were listed for a number of boiler water samples. Advantages for the use of anion exchange resin over a previously described cation exchange,resin test were explained. Determination of Fluoride in Vegetation. R. J. ROWLEY,J. G . GRIER, AND R. L. PARSONS, Aluminum Research Laboratories, illuminum Co. of America, New Kensington, Pa. The methods generally used for determining fluoride in vegetation give low results with samples high in silica. Moreover, it was shown by analysis of synthetic mixtures t h a t large quantities of silica inhibit recovery of fluoride. During ashing, there seems t o be formed a refractory compound from which fluoride is not evolved by double distillation. An alkaline fusion completely liherates this combined fluoride. Collection of 500 ml. of distillate further increases the accuracy of the determination. Although not all vegetation requires a n alkaline fusion or collection of 500 ml. of distillate, the method has been revised to include both improvements. Appreciable savings in time, as well as increased accuracy, result from these proposed modifications, which have been tested on numerous samples and known mixtures. Spectrophotometric Study of the Rhodium(I1Ij-Tin(I1) Chloride System. GILBERTH . AYRES,University of Texas, Austin, Tex., AND BARTHOLOMEW L . TCFFLY,Carbide and Carbon Chemicals Co., Division of Union Carbide and Carbon Corp., South Charleston, W. Va. The orange t o red color, which rhodiuni(II1j salts in hydrochloric acid form with tin(I1) chloride, has been invest,igated as to t h e applicability of the reaction t o spectrophotometric determination of rhodium. The transmittancy a t 476 nip is stable, reproducible, and a function only of the rhodium concentratioii. under the conditions described. The optimum concentration range is from 3 to 1.5 p.p.m. where the relative analysis error per 1% absolute photometric error is 2.8%; this range, however, can easily be ext,ended hy the transmittance ratio method t o 53 t o 62 p.p.m., where the error is 0.3% per 1% absolute photometric error. The only interfering species t h a t cannot be removed is platinum. .1 method was described whereby rhodium and platinum may be determined in situ by measuring the optical density a t two different wave lengths. These values are then used t o calculate the concentration of both the rhodium and platinum by solving two simultaneous equations, whose parameters are previously determined. The method may be applied with a high degree of acruracy except when the concentrations are highly disproportionate. Determination of Germanium in Coal and Coal Ash. WM. J. FREDERICK . ~ X DH . E. BIBER,Research and Development Laboratory L-nited States Steel Co., Pittsburgh, Pa. Because of the low percentage of gernialiium i n coal, both chemical and spectrographic methods were iuvest.igated. The cinchonine germanomolybdate method, advocated by Davies and Morgan, was found t o give reproducihle results. The high molecular weight of the compound (C19HzzONl)lHn(GeMolZ0to)makes it possible to determine minute quantities of germanium with high precision. A method has been developed for t h e spectrographic determination of germanium in coal ash, using the d.c. arc method and synthetic standards. Titrimetric Determination of Thorium. JAMESS. FRITZ AND JOHN +J. FORD, Institute for Atomic Research, Iowa State College, -4me3, Iowa. S o rapid, dependable analytical method for thorium is available. Volumetric methods involving precipitation of thorium with oxalate, iodate, or molybdate are indirect and subject to coprecipitation errors. -1method was proposed which consists of a direct titration of thorium with standard Versenate solution (disodium salt of ethylenediaminetetraacetic acid), a soluble complex heing formed. An internal indicator gives a sharp, reversible color change a t the end point. Stoichiometric results are obtained in the pH range 2.3 t o 3.4. Using -4lizarin Red S. indicator, no interference is caused by the following ions: N a + , Li', B a + + , M + + , C a + + , Mn++, Co", C d + + , Zn++, Al+'+', AgT, C r + + + , L a + + + , Voz++. The following ions interfere: P b + + , C u + + , X i + + , B i + + + , Fe++*, ZrO++, S n + + , S n + + + + ,C e + + + . Levine and Grimaldi (AECD-3186) have shown t h a t a single extract.ion with mesityl oxide separates thorium from all metals except zir-

ANALYTICAL CHEMISTRY conium, uranium and vanadium. When this extraction is followed by a versene titration, the result is an almost specific analytical method for thorium. Metropolitan-Vickers Mass Spectrometers. J. BLEARS,hletropolitan-Vickers Elect,rical Co., Ltd., Manchester, England. T h e Metropolitan-Vickers MR2 mass spectrometer has a 6-inch radius 90’ sector tube with ion source and collector arrangements based on Nier’s 1940 desigii. T h e tube is a massive stainless steel structure vertically mounted with the cold trap and diffusion pump rigidly attached in line below it. T h e MS2 was t h e first precision mass spectrometer t o utilize coni-entional !‘dynamic” vacuum plumbing methods. For example, rubber gasket,s and oil diffusion pumps are freely used with resulting simplicities in manufacture and ease of operation and little, if any, loss of performance. T h e controls of the instrument are designed t o give maximum versatility. Electrostatic or magnetic scanning can be done manually, and either single or double collector method can be used for isotope assays. T h e strip chart recorder with t h e paper drive geared t o t h e magnet sweep potentiometer has automatic sensitivity control in 8 steps covering 20,000 scale divisions with a noise level of 0.2 division and a n accuracy of 0.1%. T h e average recording time is about 10 sec. per peak. Full scale deflection on t h e n-butane (43) peak is given for a gas flow of t h e order 4.10-5 micron liters per second and thc. >taliility of cracking patterns is 1 or 2% and of relative sensitivitie* 2 or 3% per month. I n isotope assays a ratio accuracy better than 0.1 % r a n usually be expected: for multicomponent hydrocarbon gas ai~alyses,errors uwally lie between 0.1 and 0.5 mole % per roii~~~oi~en~, T1w LIS3 mass spectrometer, with a 4-inch radius tube has as broadly a similar design and performance as t h e MS2 except t h a t its maximum resolving power is 100 compared with 300 for the MS2. B y using a double inlet gas handling system and a faster st,rip-chart recorder, however, this instrument is able to handle hydrocarbon samples covering the mass range 2 t o 86 a t a rate of 6 per hour. Accuracy and Reproducibility of Hydrocarbon Analysis in Routine Plant Control with a Metropolitan-Vickers Mass Spectrometer. D . L. XICHOLSON, M. JONES, A N D B. W.BRADFORD, Imperial Chemical Industries L t d . , Billingham Division, England. T h e analytical requirements in starting u p and operating a cracking and gas separation plant h a r e been satisfactorily met by almost complete dependence on a Metropolitan-Vickers AIS2 mass spectrometer operated on continuous shifts. Both a high degree of accuracy and a wide range of analyses were called for and some of t h e analyses were roniplex. T h e need for sustained speed and accuracy led t o a n over-all study of t h e effects of mass spectrometer and computation factors. Organization of maintenance reduced loss of operating time t o a very low level. T h e major factors affecting accuracy and reproducibility were found t o be variations of ionization conditions, mainly determined by t h e state of the filament and t h e surfaces of t h e ion chamber. Computing routines were found t o introduce errors of different types which depended on the nature of t h e sample, t h e type of computing machine and met>hodused and t h e nature of t h e cracking pattern variation. ;Ircwracy could be controlled over a n appreciable range by varying t h e frequency of checking and the use of controls at t h e computation stage. Accuracy and slJeed are interrelated with the expenditure of manpower on controls and are finally determined by t h e economics of the aiialytical organization. New Monitoring Mass Spectrometer. GARDNERT ~ I L S O N AXD A. P. GIFFORD.Consolidated Engineering Corp., Pasadena, Calif.

A small, industrial mass spectrometer was designed primarily as a process monitor instrument for t h e continuous determination of a component in a gas stream. Operating characteristics were cited and instrument features were described, including provisions for batch analysis of light gas mixtures and t h e means utilized for achieving accessibility of parts and ease of maintenance. Instrument capabilities and limitations were discussed, and some typical analytiial results were presented. Method for Determination of Values for Nitrous Oxide in Blood, with the Mass Spectrometer. FRANKLIN K. DIETZLER,JOHN SAARI,ALBERTFAULCONER, JR.,AND EDWARD J. BALDES,Mayo Clinic and Mayo Foundation, Cniversity of Minnesota, Rochester, Minn. On t h e basis of problems arising in t h e induction of anesthesia, it was desirable t o develop a relatively fast and accurate method for the determination of nitrous oxide in blood. This determination was accomplished by total desiccation of t h e blood sample in a vacuum. and t h e determination of nitrous oxide in t h e residual gas, after a method de\-eloped hy Hnttns and Paari which involves t h e use of an internal *taiidai,d.

Validation of the method employ.* a technique i n which mass spectrometric determination of t h e nitrow oxide iri the gas above an equilibrated blood sample is utilized. Thus, mass jpectrometric measurements were used in calculating known mixtures, and in subsequent analysis of those mixtures. T h e accuracy of t h e method is adequate for our biologic problems, and it, is felt‘that further work will increase this accuracy. No clinical determinations have been done with this particular method as yet, although considerable work has been done on nitrous oxide analysis in blood by Hattox and Saari using a n equilibration method. T h e method described herein also has been adapted for analysis of blood samples obtained a t pressures greater t h a n atmospheric. Analysis of Mixtures of the Oxides of Nitrogen and Carbon. H . J . FREY AND G. E. MOORE, Polychemicals Department, E. I. du Pout de Nemours & Co., Inc., Wilmington, Del. T h e conventional gasometric methods for analyzing mixtures of the nitrogen oxides are painstaking and time-consuming. Attempts t o apply the mass spectrometer t o the analysis of such systems hrts proved t o be difficult because of t h e mutual interference of many of t h e romponents and t h e erratic behavior of nitrogen dioxide in t h e instrument. We have devised a rapid, previae method employing both the mass and ultraviolet spectrometers for the analysis of gases containing components such as N20, Con, CO, Nz, NO, NO?, and Oz. T h e procedure involves the direct determination of nitrogen dioxide by its ultraviolet absorption. T h e sample is then run on t h e mass spectrometer t o obtain its basic pattern. This pattern is not directly solvable because t h e erratic mass pattern of t h e NO2 present in t h e sample seriously interferes with the determination of t h e NO and NpO. T o remove this interference, t,he sample is passed over solid potassium hydroxide t o remove both t h e NO? and COS. T h e pattern of t h e residual gas, which may contain 0 2 or NO, N?O, Nz, and CO can he readily solved. T h e relative ratios of these components allow the results t o be translated t o concentration values on t h e original sample, and, in addition, permit t h e determination of COz. T h e rahie for N0z obtained by t h e ultraviolet method is normalized with t h e remainder of the data t o provide a complete result. Mass Spectrometer Analysis of Mixtures Containing Nitric Oxide and Dinitrogen Tetroxide. R. A. FRIEDEL. 9.G. SHARKEY,J R . , JANET L. SHULTZ,. ~ N DC. R. HUMBERT, Bureau of Mines, Synthetic Fuels Research Branch, Bruceton, Pa. Mass spectrometric analyses h a r e been carried out’ successfully on

NO? and NO in admixture and in mixtures containing CO, COz,

Nz,02, and H20. iinalysis of NO2 requires prior conditioning of t h e spectrometer, after. which t h e spectra are reproducible. For all NOz partial pressnres between 15 and 200 microns, behind t h e mass spectrometer leak, t h e sensitivity of t h e principal mass peaks are essentially independent of pressure. D a y t o day reproducibility of these principal sensit,ivities is comparable t o t h e results for hydrocarbon gases. Below 15 microns t h e NO2 spectrum changes rapidly with decreasing partial pressure. B u t t h e reproducibility of spectra on a particular day, at a given pressure, makes possible t h e analysis of NO2 even in this pressure range. Absorption Curves of the Peroxide Complexes of Elements Present in High Temperature Alloys. MARYLOUISEBACON. Westinghouse Electric Corp., Materials Engineering Chemiral Laboratory, East Pittshurgh, Pa. T h e photometric determination of titanium by hydrogen peroxide involving a minimum separation of e1ement.s has been investigated for possible application t o t h e analysis of high temperature alloys. A spectrophotometric study was made of t h e absorption of t h e peroxide complexes of iron, nickel, chromium, molyhdenuln. cobalt. and other elements which may he present in high temperature alloys. T h e study made it possible t o select a wave length for t h e titanium color measurement at which t h e absorption and interference by t h e other elements present permitted sufficiently acrrimte titanium results on synthetic solutions. ~EY, Derivative Polarography. N. F. LEBL-INC,J. E. ~ I C ~ A R I AND C. M . WRIORT,Hercules Experiment Station, Hercules Powder CO., Wilmingt.on, Del. Derivative polarography is a technique in which the fiwt derivative of a polarographic curve is obtained instead of t h e curve itself. Theoretically, this should be useful in determining substances with only slightly different half-wave potentials, and for determining small concentrations of reducible substances in t h e presence of much larger concentrations of other reducible substances. Interest in derivative polarography has recently been stimulated by Leveque and Roth, who have reported a differentiating circuit fol. use with photographicrerording galvanonietev type polarographa.

V O L U M E 25, N O . 3, M A R C H 1 9 5 3 This paper descrihed a successful adaptation of the Leveque-Roth circuit t o a Sargerit Model XXI polarograph. T h e utility of this adapted circuit is shown by the rapid determination of small amounts oi dichloroacetic acid in a twenty- t o fiftyfold excess of monochloroacetic acid. This determination is impossible by ordinary polarography, and is long and rather inawurate by chemical procedures. However, t h e Leveque-Roth cirvuit has some inherent drawbacks ,Ircordingly, some other approacahes to derivative polarography were diwussed, along with the underlying theory of derivative polarography. Determination of Lead in Tin. , J . s M E ~P. ~ MC,KAVESKY .LSD WM. J FREDERICK, Researrh aiid Development Laboratory. L-iiited States Steel Co., Pittsburgh. Pa. T h e conventional method for t h e determination of lead i n tiu involves a double alkaline sulfide precipitation followed by the electrolytic determination as PbOa. T o overcome this long tedioua method, t h e tin was volatilized as bromide and the lead determined in t h e residue with t h e polarograph. T h e results rompnrerl favorahly v-ith t h e results by t h e conventional method. Comparison of Methods for the Spectrophotometric Determination of Fluorides. J. C. BARTLET ASD R. A. CHAPMAX. Food and Drug Laboratorie?, Department of Xational Health and Welfare, Ottawa, C':inada. dpectrophotometi ie tiierliodb for the deterniinattoii oi fluorides d e pend on the bleaching of a colored metal complex by fluoride ion. Colored complexes of irou, aluminum. titanium, zirconium, and thoriuni have been used a> reagents for t h e deterniiriation of fluorides. T h e sensitivity and reprotlucibility of several such methods were disvusbed. T h e ferric, salivylate method has been studied in detail, and a.hile t h e sensitivity i.* le,->thau with some other met,hods, reproducibility is excellent. Si1ic.e the reagents for this proceduie are veadily arailable, relatively itaide. and t h e reaction is immediate, t h e femic s:ili,,ylate method ha1 ili-titti,t adrantage.; ovet' other pror,erlut,es i t utliect. Round Table Discussion of the Determination of Ferrous Oxide in Sinters, Ores, and Refractory Materials. F. MILLER,hlellon Institute. Pttt.iiurgh, P a . , Panel: JAMES I. DISSIS. U. 9. Geological Sur ('hairinan; JOSEPH riited States Steel C'r)., Pittshurgh. .Jones & Laugliliti Steel Corp., Bethleheni Steel G o . , Pittbhurgh, Pa.: W\LTI,:R S . ZOT,I,ISC;EH, Bethlehem Pa. This was an i i i f o i ~ ~ ~iiismssion ial of t h e deteriiiiiiatioii OF ferrous oxide in naturally occui'ring o i ' e s and minerals as well a,. i t 1 such proce+ed niaterials as b1a.t fwiiace sinter arid refractories. T h e discuasion dealt with such favtors as the digestion system, the digestion time and temperatut,e. t h e sigiiificaiire of and mean> of maintaining a nonoxidizing atmosphei'e. t h e use of boric acid where hydroflucric acid IS used in digertioii. the titrant, and t h e mean- of detecting t h e titi,atioii end point. In addition. some discussioii of methods for detemiiiiing metallic. iron and its effect on t h e ferrouo oxide drtel~minatioti was included. Tht,ougli open discussion it is hoped that t h e coni u d atmosphere may ))e cleared and t h a t some c~on-tr.ur~tire advaii(.einerit may be made i r i the direction of an act-urate : i i i ( I prerise uuiwrially adaptable tiiethod foi. determination of ferrou. oxide.

523 Mass Spectrum of Lithium Iodide. L E W I SFRIEDMAN, Department of Chemistry, Brookhareii Satioiial Laboratory. Upton, L . I., N. P. T h e mass spectrum of lithium iodide vapor produced by heating single crystals of the compound in a n oven in the ion source of a General Electric analytical mass spectrometer has heen investigated. T h e results indicate association of neutral molecules in the vapor phase. T h e intensities of the various atomic. and molecular ions have been measured as a function of t h e salt temperature. Theve together with appearanre potential studies on t h e various ion species permit the calculation of heats of sublimation of t h e ionic crystal and dissociation of LiI molecules which are in good agreement with t h e results of Mayer and Helniholz in a theoretical study of the latt,ire energy of lithium iodide. Heats of dissociation of some polymeric speries of lithium iodide ha\-e also been deduced. High-Temperature Mass Spectrometer Oven. J B . W.ILTI)S. Oak Ridge National Laboratory. Oak Ridge, Tenn.

A high temperature ma pevtrometei oren has been dereloped t o use with t h e Nier type source. This oi-en is fabricated from tantalum or platinum. and c~ontrollabletetnperatu~eht h a t approach t h e meltitig point of these metals have heen attained. This type of oven has also afforded an ogpoi'turiity to investigate t h e thermal ions of a variety of elements. M a s s Dependence of the Gain of a n Electron Multiplier from Observations on K-39,Na-23, W-184,and U-238. F. A. WHITEA N D T. L . C O L L I N SGeneral . Elec~tric~ Co.. Kiiolls Atomic Power Laboratory, Schenwtady, N. 1'. The gaiii of a11electron multiplier G of n stages can be considered as t h e produc-t F- X Mn-1 where E' is t h e number of electrons per incident. positive ion arid Mn-l i- the over-all secondary electron gain of t h e remaining vtages. T h e factor Mn-1 can he assumed t o be a ronstant for hhot,t pei,iods i f certain preraiitions are observed. By nieabw i n g input and output current. simu1t:ineouily on two recorders, t h e elect,ron yield I' per positive ion v,xi dir.ertly tiietisurahle and rarried out for foul, widely different mabae:. Reliable Method of Counting Individual Positive Ions in a Mass Spectrometer for Beam Current of Less than Ampere. F. A. TTHITE,T . L. COLLISS,AND J. C . S H w T I E L L ) . Geiieral Electric co., Knolls Atomic Power Laboratory, Sehenectady, N. Y. For two years small heam currents have heen meaJured by a 2 stage Allen type electron multiplier in conjunction with fast scalei discriminators, and suitable recorders. By counting resolved PUIS rather t h a n using t h e multiplier as a d.c. amplifier, many disadvaritages of this type of detector are rendered negligible. Currents of 10-'* ampere can be observed easily n-ith a background current of about 20 pulses per minute (approximately 5 X ampere). T h e one t o one correspondencae of inc+lent positive ions t o output pulses has been verified. Lubricating Oil Analysis by Thermal Diffusion and Mass SpecR. BROWN, T. A. WISHALL,W. trometry. F. W. MELPOLDER. DOHERTY. \ S D IT. S . Yorrxvc, T h e Atlantic Refining Co.. Philadelphia, Pa.

The experimental methods for obtaining mass spectra of solids were reviewed. T h e latent methods now under investigation were described. Specific to1.iic.s iiirluded ion sources. snniple introduc,tion, and high resolution.

High teiiiyerature mass spertroiiictet. analy-;es were u3ed t o evluate the thermal diffusion process for reparating light lubricating oils into hydrocarhoii types. .In eicmohane distillate stock c,ontaining between 17 and 22 carbon atoms was initially percolated through t h e silica gel t o separate paraffins froni aromatirs. Eavh of these fractions was then subject t o t h e thermal diffusioti proreds in hatchwise operations. Significant separation. were ohtained between iio and normal paraffins as well as between ririg conipoundi oc.c.urring in hoth the paraffin and aroniat ir fraction>.

M a s s Spectrometric Study of Germanium. R . E. HoYicz. I.ahoratories Division, Radio Corp. of r\merica, Prilicetoii. S . J .

X-Ray Fluorescence Spectroscopy. H. E'RIEDXLSA N D I. BIRKS,L-.8.Naval Researvh Laboratory, Washington, D . C .

.I mass spectrometric method, employed in ronjunction with a physical process of impurity enrichment, has yielded semiquantitative analytical results on gerinanium samples used in tran&tor work. Aftei a two-stage treatment in a gradient furnace, t h e enriched sample is vaporized thermally in a mass spectrometer. a t temperatures t h a t are raised in suitable steps. -1s a result, most impurities are separated, in temperature and time, from t h e bulk germanium. I n this fashion, it seems posaible t o extend instrumental seti.;itivities from a present mole fraction limit of t o perhaps 10-8. d f t e r t h e sample is completely evaporated, a time integration of ion currents yields concentration estimates, whose accuracy is mainly limited by unrertainties in t h e ionization rross-jections. In analyses made on germanium, small concentrations of the following impurities were found: As, P, Sb, Sn, P b , Fe, Zn.and C d . Calibration runs made on Fe, Sn, and Pb show that thebe Group 11' element. evaporate partially in moleculai~f o m i .

I n an x-ray spectrograph t h e x-ray tube is t h e primary source of radiation, corresponding t o the electric arc or spark in emission spectroscopy. T h e specimen id excited t o fluoresence hy t h e photoelec. tric action of the primary ray;;. h portion of the fluorescent radiation may be passed through a collimat,oi consisting of parallel plates or a bundle of tubings and is dispersed by reflection from t h e face of a crystal grating such as rock salt or mica. T h e analogous apparatus for emission spectroscopy is a simple prism spectroscope with light rendered parallel by an optical lens. Focusing spectrographs for x-rays use bent crystals as diffraction gratings in geometries similar t o Rowland mountings of t h e ruled concave gratings used in optical spectrographs. T h e intensities of t h e x-ray apectruin lines may be measured by a Geiger counter, proportional counter, or scintillation counter, each of which has a quantum counting efficiency nearly equal t o unity over most of t h e soft x-ray spertrum. T h e qperiiiieii f o i . u-ray ai:aly-i> may lie d i d , liquid. 01' gaaeol.is

Mass Spectrometry of Solids. Bethlehem, Pa.

E. J . S E R F ~ S Lchigh S. L-iiiversity,

H.

524 and is not detectably altered physically or chemically by expobure t o t h e primary beam. T h e intensity and quality of t h e primary x-ray beam vary only with t h e tube current and voltage, both of which can be well stabilized. I n contrast t o emission spectroscopy the excitation conditions for t h e source are therefore easily standardized and duplicated from sample to sample. Perhaps t h e most striking difference between x-ray fluorescence analysis and optical emission spectroscopy is t h e very small number of lines in the characteristic x-ray spectra. X-ray analysis is niobt efficient in t h e region of the first transition group of elements, where concentrations from parts per million t o 100% can be measured with accuracy and speed. The efficiency is affected by the power rating and design of t h e x-ray tube, t h e sensitivity of the detector and t h e spectral resolution required for the particular analysis. Future improvements in x-ray tubes and detectors should permit comparable efficiencies t o be obtained for elerneiit-; a t t h e higher and lower atomic. number extremes. Progress of X-Ray Spectrography in New Applications. FREDA . BEHR,North -1mcrican Philips Co., Mount I'eriion, N. 1 ' .

ERICK

A N A L Y T I C A L CHEMISTRY and time required for an analy Likewise, the results obtained by fluorescent x-ray spectrograph nethods were compared with those obtained by optiral spectrographic. and chemical analyses. Nondispersive X-Ray Fluorescent Analysis. M F. HASLER LSD J. W. KEMP, .Ipplied Research Lahorstories, Glendale, Calif. The method of analysis discwsed is baaed on the recording of iiondispersed fluore.weiit x-radiation with an x-ray filter photometer. Irradiation of R material with hetei.oc~hroinatic.x-radiation excites the x-ray spectra of elements preaent in the inaterial. These spectra may be studied with dispersive analyzers of herera1 types [see, for instanre. P. H . Koh and Bet,ty Caughei,ty, .J. d p p i . Phys., 23. 427-33 (1952) 1. For niate;.ials containing reaaonahle ronrentrations of a few elenients, R qiinpler method ia nvailahle. If the exritation voltage of the primary heterochromatic radiation is properly chosen and controlled, and the resulting fluorescent radiation passer1 thi.ough a filter of a correctly chosen element, the fluorescent spectra of all elements in the matei,ial except t h e one being analyzed foi ('a11 often he suppressed sufficiently to allow a high precision analybi. t o he made. Basic studies have been made t o detei mine the prevision. sensitivity. and limitations of the method. High prec~isionran be obtained by two methods, internal atandard or exteriial standard. I n the internal standard method, the ratio of two fliioi'esr.ent beams from the same sample is measured, one beam being filtei,ed to rei,ord the major constituent element, and the other to record the element, being analyzed for. I n the external s t a i d method. a standard sample and t h e unknown are irradiated the same primary heam, the intensity ratio of the filtered fluo cent spevtra from each sample being measured. Extension of the method to the simultaneous analysi.. of qereral elements is tieing studied. 3

T h e x-ray spectrographic method as now availahle, using the newest concept in instrumentation, differs radically in application from t h e method historically practiced by Siegbahn, Moseley, and others. T h e availability of more efficient detection, electronic controls of counting circuitry and stability of x-ray output have placed t h e method in t h e forefront of modern analytical methods. T h e analytical method suitable in industrial control purposes, must be flexible, reproducible, with combined accuracy and speed. Furthermore, it must be operable by nontechnical personnel. The x-ray spectrograph is readily adaptable t o meet such control requirements. Most recent applications in the industrial field are outlined, and the limits of reproducibility and sensitivity which have been achieved were discussed. Application of Fluorescent X-Ray Spectroscopy in Metallurgy. G. E. KOAKES, Ford Motor Co., Dearborn, Mich. An investigation was undertaken to determine the applicability of fluorescent x-ray spectroscopy for control analysis of metallurgical samples. Three materials were studied. For a nickel-chrome alloy, comparative data were obtained by x-ray fluorescence and by emission spectroscopy to evaluate fully their respective advantages. I t was found t h a t by x-ray fluorescence linear calibration graphs could be obtained over a wider range of composition than by emission spectroscopy. T h e time required for a n analysis for five elements in t h e metal is comparable for each method. T h e reproducibility of analysis is about t h e same for the two methods. Emission spectroscopy is capable of analysis a t very low concentrations: x-ray fluorescence spectroscopy is limited t o concentrations above about 0.3% for most elements. Fluorescent x-ray spectroscopy is more representative of the sample than emission spectroscopy. I t is estimated t h a t t h e contributing volume is 1000 times as great az in einission spectroscopy. Powdered iron-copper metal samples were studied. High sensitivity and good reproducihility for copper were obtained for hand mixed samples. Sintering affected t h e sensitivity, and copper determinations on production mixes did not agree with chemical results. I n powdered copper-tin mixes, analyses were possible on either hand-mixed or production samples, sintered or unsintered. Sintering has a slight effect on t h e sensitivity. The only disadvantage is the low sensitivity of t h e instrument for elements having wave lengths as low as tin K alpha. From this investigation, it is concluded that under standardized conditions fluorescent x-ray spectroscopy may be used for rapid, accurate control analyses for most of t h e elements present in t h e nickel chrome alloy studied or similar alloys, but has limited use for analyses of samples containing powdered copper and iron.

X-Ray Fluorescence Analysis for Major Constituents. ,J. SHERNaval Shipyard, Philadelphia, Pa. A natural analysis of x-ray fluorescence measurements is derived from the fundamental properties of x-ray absorption. Simple algebraic transformations linearize t h e functions used for analysis of multiple components, in thick and thin specimens. T h e method was presented and illustrated by a n application t o the analysis of major components in 3- -4 component bronze alloys in thick samples. Under suitable condit,ions the precision expevted is about 0.5% of content.

M . ~ N Philadelphia ,

Quantitative Determination of Bromine in Liquids by Means of X-Ray Fluorescence. G. T. KOKOTAILO AND G. F. DAMON. SoconyVacuum Laboratories, Paulsboro, N. J. An x-ray fluorescence method has been developed for t h e rapid and precise determination of bromine in liquid hydrocarbons. T h e presence of iron and sulfur as impurities in the hydrocarbons seriously affects the intensity of bromine fluorescence. A known quantity of selenium is added t o the sample and the ratio of bromine t o selenium fluorescence is determined as a function of bromine content. This ratio for given bromine concentrations remains the same within experimental error with the addition of iron and sulfur as impurities. Selenium was chosen as t h e internal standard a3 it is next to bromine in the periodic table, and its fluorescent yield and absorption properties are almost identical t o those of bromine. A series of calibration curves for hydrocarbons of densities 0.70 t o 0.92, with 0 t o 0.4 weight % bromine added, were determined. Using these curves it is PO+ sible t o determine bromine t o *0.01 weight in this range. Samples wit,h greater concentration are brought into this range by dilution. T h e method uses a North American Philips fluorescence unit and t h e characteristic bromine and selenium radiations are excited by molybdenum radiation. d single analysis requires about 15 minutes to complete.

Application of the Fluorescent X-Ray Spectrograph to the Analysis of Niobium and Tantalum in Ores. WILLIAMJ. CAMPBELL AND HOWARD F. C A n L , U. S.Bureau of Mines, College Park, M d .

Determination of Tetraethyllead in Gasoline by X-Ray Fluoresw. LAMB,LEONARDM. N I E B Y L S K I , A N D EDWARD cence. FRANCES W. K I E F E R , Ethyl Corp., Detroit, Mich. I

Three methods of applying t h e fluorescent x-ray spectrograph to analysis of niobium and tantalum in ores are discussed. A method previously reported consists of t h e determination of the Nb2Os:TarOs ratio in a mixture of these oxides chemically separated from the ore. Another method involves direct analysis of samples by using a series of prepared standards having a matrix composition similar t o t h e ore samples and hence similar x-ray absorption and emission characteristics. T h e most recently developed method is direct analysis of ores by application of internal standard techniques t o fluorescent x-ray spectroscopy. T h e basic principle of this technique, types of standards used, and t h e results obtained were discussed in detail. ThePe three methods were rompared Tith regard t o their reliability

An investigation has been made of t h e application of x-ray fluorescence t o t h e determination of tetraethyllead in gasoline. A comprehensive study has been made of the extent of the matrix effect both from theoretical and experimental considerations. T h e calculated linear ahsorption and scattering coefficients of t h e matrix at t h e ware lengths involved show t h a t the intensity of the measured lead fluorescence will be decreased as t h e carbon t,o hydrogen ratio of t h e base stock is inrreased. These data also show t h a t the measured fluorescence will decrease with increasing sulfur content. These two effects have been determined quantitatively and a method has been developed for applying a direct correction t o t h e measured intensity of the lead fluorescence. The fluorescence method has been found t o be capable of a precision and accuracy equal to that obtained by the x-ray absorption iiiethod as experienred n-ith the double-beam null-

V O L U M E 25, N O . 3, M A R C H 1 9 5 3

525

type G.E. x-ray photometer. T h e x-ray fluorescence method has the decided advantage t h a t a direct determination can be made of t h e type of antiknock fluid present because t h e bromine m n t e n t of t h e gasoline m a y be determined directly by x-ray fluorescenre. The requirements of source stability, sensitivity, sample size, resolution, rounting time, etc., for obtaining a specified accuracy have been evaluated: From a consideration of these factors a satisfactory compromise of conditions has been selected for use as a rapid. routine analytical method for tetraethyllead in gasoline.

oxide. The rtiixtuie of o w aiid horou trioxide ih then inised with graphite and t h e whole compressed into a pellet in a briquetting press. After a quick heat treatment, t h e pellet is attached t o t h e rotating mechanism in t h e spectrograph and excited with a high voltage spark directed against its edge. Woi.kiiig curves have been developed for silica. alumina, lime, and othei element\ can be determined. T h e riiethod is accurate. reproducible, aiicl applicable to a wide variety of i i o n ores.

Quantitative Spectrochemical Determination of the Alkali Metals in Silicate Rocks, Minerals, and Meteorites. L. H. AHRENS,Department of Geology, Massachusetts Institute of Technology, Cambridge, Mass.

Spectrochemical Determination of Impurities in Cobalt Oxide. .JOHS H. MCCLURE AND R. E. KITSON. Poly(,hemicals Department, E . I. du Pont de Nemours & Co.. Inc.. Jl.ilniington, Del. Spectrographic methods were del-eloped for the determination of c,;ilriutn, hatiurn, copper. silicon, iron. manganese, chromium, alumit i r i i n . and nickel in cobalt oxide (CoaO4). T h e procedure is rapid as (~oiii!mredwith other c~hemiraland instrumental methods in those cabes \\.here they ( ~ U I Ibe applied. -4statistical study of t h e precision 207, relative over the concentraindirate- :I atandard deviation of tion mnge 0.001 t o O.lY,. The line p a i v and their usable ranges mere given togethet. with a solution method for t h e preparation of standard samples.

T h e alkali metals have similar spectroscopic properties (].ate+ of volatilization, first ionization potentials, excitation potentials) arid in devising a n analytical scheme-see Ahrens, 1951, for euanip!e-it is logical t o consider t h e determination of t h e five alkali metals as a group. In t h e procedure employed a t t h e Cabot Spectrographic Laboratory. M.I.T., t h e alkali metals are determined in one, or perhaps two operations, depending upon whether an internal standard is iised and on t h e concentration of each alkali metal. T h e powdered sample is loaded into a conventional cupped carbon anode and is excited by t h e d.c. arc; exposures are variable and are timed by the (lihappearance of t h e flamelike character of t h e discharge. Because of a similarity in spectroscopic properties, highest accuracy is attained by using one alkali metal as a n internal standard for the determination of another. Geological materials vary enormously in composition and accordingly methods have been developed which are capable of accurately iietermining each alkali metal over a large concentration range. I n the example of potassium, t h e range is from 0.001% t o about 5%. At high concentrations-as in granite, for e x a m p l e t h e accuracy of the spectrochemical method is about equal t o t h a t of t h e usual Lawrence-Smith fusion procedure: a t medium concentrations (0.21, t o 1.5Yc) as in basalt and diabase, for example, t h e spectrochemical method is somewhat superior whereas a t low concentrations (0.001 % to 0.1%). as in peridotites, dunite and chondritic meteorites, it is fa!. superior. Recent spectrochemical investigations show t h a t t h e chemical values may be too high by a factor of 30 t o 40 when tlie potassium concentration is very low. These observations are of considerable geophysical interest because t h e radioactivity of K40 is a source of earth heat and much of t h e earth's interior is probably composed of material of peridotitic or dunitic composition. Much interesting geochemical and cosmochemical information habeen provided by t h e use of these quantitative methods for determining the alkali metals in silicates and i t has been possible t o demonstrate for t h e first time t h a t t h e ratio of two elements ( W R l ) ) in t h e earth is t h e same as in cosmic material (meteorites). Quantitative Spectrochemical Determination of Germanium in Ores, Residues, and Ashes. J . 8. BRYBOS, Eagle-Picher Co.. Joplin. hlo.

.i quantitative spectroc-hemical prcedure for the determination of germanium in ores. residues, and ashes using lithium carbonate as btiffei, and internal standard was described. Detail> of .ample preparation and some precision data n-ere given. Spectrochemical Study of Rare-Earth Elements in Cerium Minerals. H. J. ROSE. JR.,K . J . h f T - R \ T i . AND bf. K. CARROS. Geochemisrry and Petrology Branch, C . S. Geological Survey, Washington. D . C. Current niineralogic studies on cerium minerals from newly discovered deposits in California and Montana h a r e focused t h e attention on t h e composition of these minerals with respect to t h e ceriumearth elements. Cerium is determined volumetric~ally and a tot,al rare-earths precipitate is separated chemically from another sample for spectrochemical analysis. T h e spectrochemical method used is an extension of t h e one developed by Fassel [ J . Opt. SOC.A m . , 39, 187-193 (1949)l. Cerium is used a s internal standard for determining t h e perrentages of La. Pr, Nd, Sm, Eu, Gd, and Y with a n average deviation of 5%. D a t a on these elements in a number of different cerium minerals from a single deposit and in a single cerium mineral (monazite) from a number of different deposits were reported. Spectrographic Analysis of Iron Ore. 6. W. bf.msEx AND G . J. MCQUIVEY,Columbia-Geneva Division of U. S. Steel Co., Geneva. Utah.

A spectrographic method for t h e analysis of iron ore has been developed which takes advantage of t h e unique characteristics of a rotating electrode t o effect considerable savings in time and materials as compared t o conventional chemical methods. I n t h e method developed, a specially prepared sample of ore is weighed and mixed by grinding with a weighed quantity of boron tri-

+

Spectrographic and Quantometric Analysis of Lubricating Oils. . J A ~ KGILLETTE, Applied Research Laboratories, Glendale, Calif. A rapid method of determining metallic impurities and additives in lubricating oils is essential for engine wear studies, and as an aid t o preventive maintenance. A method of direct spectrographic analysis using the ARL rotating disk electrode was described. A weighed amount of cadmium naphthenate is added t o each sample as t h e internal standard. Approximately 0 . 5 ml. of sample is required and a complete analysis can be made in 10 t o 15 minutes. B y recording the spertla on the ARL Quantometer, t h e analysis time is reduced to about 5 minutes. Complete details of procedure were given. An over-all standard deviation of about & 10% can he expected.

Methods of Excitation for the Spectrochemical Determination of Trace Elements in Titanium Dioxide. L. 13. OLMSTED,Titanium Dirilion. National Lead Co.. St. Loiiib, Mo, Two types of excitation, a d.-c. atid an ovei.damped R.lu1tisourr.e rondition have been used in t h e routine aiialvhis of titanium dioxide. ..inovel arrangement was described fot mounting pelletized samples on a graphite elertrode base. Changes in t h e chemical nature of t h e pellet during the "interrupted arc" exposure have been studied. Scribner-type pedestal electrodes have been used with t h e d.-c. arc; some of t h e factors affecting t h e precision of the d.-c. analyses have been subjected to statistical analysis. Analysis of Virgin Petroleum Naphthas by Mass and Infrared Spectroscopy. B. IT*. THoar.is. .T. A . h D E R S O N , JR., A N N E L L E ELLIOTT, H. E. LI-MPKIS. ksn R . B . WILLIAMS, Humble Oil and R e fining Co.. Baytown, Tex. Individual component analyses tiy mass and infrared spectrometry n-ere compared for virgin petroleum naphtha fractions and for synthetic mixtures in t h e CS-200' F. boiling range. I n t h e XXb26Oo F. boiling i'ange, mass spectrometer i~e-.ultswere compared with known rompositions of synthetic mixtures anti with ittfrared spectrometer analyses of virgin naphtha fractions. -4nalyser obtained on fractions in t h e 235-247' F. range by coml~ining*elected data from mass and infrared spectra were presented and the procedure was discussed. A rapid scheme of analysis for obtaining individual paraffin, naphthene, and aromatic compounds in t h e Ca-260' F. boiling range by maw spectrometer alone was outlined. Gain Control of Mass-Spectrometer Amplifier. S. MEYERSON, H. hf. GRUBB,ASD 1%'. H. h f O E L L E R . Research Department, Standard Oil Co. (Indiana),Whiting. Ind. T h e direct-current amplifier in a Consolidated analytical mass spectrometer has been modified t o proride adjudable gain. T h e modifications include a network of variable resistances in the d e generative feedback loop and a hridge circuit as an aid in adjusting these resistances. Adjustable gain permits maintenance of a ronstant over-all instrumental sensitivity a t a preselected level and provides for independent electrical correction of gas sample preqsures t o a standard value. Two variables t h a t must be considered in t h e computation of an analysis are thus eliminated. I n addition, use of a gain-selector switch permits increase of gain by an integral or other preselected multiple with transient-free switching. Computed Calibration Data for Gas Analysis by Mass Spectrometer. S. MEYERSON, Research Department, Standard Oil Co. (India n a ) , Whiting, I n d . Correlations with n-butane pattern coefficients a t m l e 13 and 15 have been derived for t h e relative sensitivities and pattern coeffi-

ANALYTICAL CHEMISTRY cients of twenty compounds and mixtures for which calibration d a t a are required for gas analysis by t h e mass spectrometer. D a t a obtained with eight different T y p e I11 ionization chambers in a Consolidated Model 21-102 mass spectrometer over a period of four years were correlated t o establish a master calibration file covering t h e range of operating temperatures normally encountered. T h e time required for calibration for gas analysis has been reduced t o 45 minutes on t h e instrument and about four hours of computation. T h e correlations should hold for other instruments of t h e same model. Comparison of experimental and computed values of a few selected pattern coefficients permits easy recognition of abnormal operation. If operating temperature can be maintained constant, newly installed ionization chambers show normal operation n-ithin 2 t o 3 days after operation on usual samples is resumed.

Echelle Spectrography. GEORGER. HARRISON,Massachusetts Institute of Technology, Cambridge, Mass.

J. RI.

Application of Echelle Spectrographs to Qualitative and QuantitaAND IT. G . tive Spectrochemical Analysis. N. A . FINKELSTEIN K I R C H ~ ~ E S S BBausch E K , and Lomh Optic-a1 Co., Rochester, N . Y.

Structural Qualitative Analysis from Mass Spectra. MCCREA,M. W. Kellogg Co., Jersey City, N. J.

A Diophantine method of analysis is useful in t h e assignment of empirical formulas t o t h e ion fragments corresponding t o the various m / e values observed in mass spectra. Characteristic mass spectral groups, which occur when polyisotopic elements such as chlorine, bromine, or sulfur are present, fix t h e number of atoms of these elements in a given fragment. T h e reconstruction of t h e molecule from the fragments so identified leads t o an assignment of structure. Possible structural ambiguities must be resolved by other methods. Mass spectrometric measurements of effusion rates provide confirmatory data when two components are present. A formal analogy is developed between mass spectra structure studies and t h e assignment of structure on t h e basis of functional group frequencies in the infrared. Correlations of available mass spectral d a t a form a basis for t h e rapid identification of components; such correlations were presented for t h e CFz=CFX and CHz=CFX molecules, where X may be H , F , C1 or Br. Use of the various methods is illustrated by appropriate examples, including a comparison of t h e mass spectrometric and infrared spectrophotometric methods for t h e determination of purity in polymerization-grade CFZ=CFCl. Identification and Determination of Volatile Atmospheric Pollutants. FREDW. MCLAFFERTY, GERALDE. CLOCK,AND ROLAND S. GOHLKE,T h e Dow Chemical Co., Midland, Mich.

A rapid sensitive method for t h e detection and determination of volatile pollutants in t h e atmosphere was described. The unique advantages of t h e mass spectrometer for this type of analysis have been illustrated by two previous publications. This method, however, has advantages of small sample requirements, fewer mass spectrometer analyses, sensitivity, and speed which makes it particularly suitable for t h e routine survey of industrial plant areas for possible atmospheric hazards. T h e foreign vapors are condensed from t h e air a t about - 175' C. in a t r a p placed in a metal liner cooled in liquid nitrogen. Vapor, oil, and water phases are separated from t h e condensate, their amounts determined, and portions of them are analyzed on t h e mass spectrometer. Recoveries of around 95% were found on most control mixtures. Results ftom several plant problems show the usefulness of t h e method in identifying and determining many unsuspected atmosphere pollutants. Mass Spectrometric Analyses of Six- and Seven-Carbon Alcohols. V. A. Y A R B ~ R O U GCarbide H, and Carbon Chemicals c o . , South Charleston, W. Va. A method was described for t h e mass spectrometric analysis of sixand seven-carbon alcohols. Simultaneous equations are employed for t h e analyses of mixtures of 1-hexanol, 2-ethyl-1-butanol, 2-heptanol, 3-heptanol, and 4-heptanol. T h e use of determinants t o calculate the contribution of a given component t o a selected mass peak as described. T o test t h e method, its accuracy and reproducibility, three mixtures of a known composition have been analyzed. The reproducibility is within & 5 % of t h e value of the contained component. T h e average deviation of a given component from its known value is 8%; t h e maximum single deviation is 19% of its known value. A modification of the mercury orifice used for t h e introduction of liquid samples into t h e mass spectrometer was presented. Mass Spectroscopic Studies of Mixtures of Water and Deuterium Oxide. JOHN L. WARNECK, Westinghouse Research Laboratories, East Pittsburgh, Pa. Mixtures of various percentages of mater and deuterium oxide were made u p and analyzed by t h e mass spectrometer. Analytical and equilibrium results were tabulated and suggestions a s to methods and procedures are given.

Echelle ipectrographs of a t least six differelit types have now been constructed, following t h e principles previously discussed by t h e speaker. Three types of echelle instruments have been designed and constructed by the Bausch and Lomb Optical Co. and two types a t M . I . T . All these instruments involve the crossing of Bausch and Lomb echelles having from 200 to 2000 grooves per inch, with either a prism or a concave grating. They have been found t o give greatly increased resolution a t normal speed, or high speed a t normal resolution, and are compact, stable, and easy t o use. Methods of measuring wave lengths and intensities with echelle instrument? were discussed, with special reference t o t h e needs of workers in spectrochemical analysis. Calibrations of t h e type needed for such work were demonstrated.

T h e echelle qualities of high i n t h r i c angular dispersion and spectrum energy concentration can be used to excellent advantage in both qualitative and quantitative spectrographic. analysis. Two iiistruments incorporating this new dispersillg element have been constructed and applied t o analytical problems. The first, a n internal mounting of the echelle behind a Littrow prism, provides a dispersioil varying from 1.09 A./mm. a t 8000 -4.t o 0.33 A./mm. a t 2000 A . T h e second instrument is an external mounting of a n echelle with auxiliary reflecting optirs designed t o be used in conjunction with a n y stigmatic spectrograph of moderate dispersion. The Echelle attachment provides linear dispersions similar t o t h w e of the internal mounting. I t has been successfully crossed with a conventional large Littrow prism instrument and with a 2-meter Viadsworth concave grating spectrograph. Resolving powers on t h e order of 150,000 have been obtained with t h e usual arc and spark excitations in routine analytical measurements performed on both types of echelle spectrograph. A typical quantitative application has been t h e analysis for boron in steel using the 2497.73 boron line ordinarily interfered with by the 2497.82 line of iron. Other echelle applications investigated include a hyperfine structure study of praseodymium in which the six component configurations were resolved and measured. New Direct Reading Spectrometer for Magnesium Alloy Analysis. J. L. SAUNDERSON, Baird Associates, Inc., Cambridge, Mass., T. M. HESS, V. J. CALDECOURT, H . H. GROSSMAN, AND C. A. SAUER (Dow Chemical Co., Madison, Ill.), T h e n o w Chemical Co., Midland, Mich. The new direct reading spectrometer recently installed a t the Jladison Division of T h e Dow Chemical Co. was described. The instrument, which was built by Baird Associates, Inc., was designed t o analyze for eighteen elements in commercial magnesium alloys. Special features discussed include problems of extreme optiral stability, built-in testing procedures, and the method developed for the analysis for iron down to 0.0005%. Analytical results were discussed from the standpoint of precision and drift, New NSL Projection Comparator Microphotometer. J. T. Rozs.4 AND C . G . M o m , National Spectrographic Laboratories, Inc., Cleveland, Ohio. T h e newest member in instrumental analysis known as spectroscopy is t h e KSL Spec-Reader. T h e design has been made to reflect t h e comments and suggestions of industrial spectrographers t o effect an integrkted unit t o handle a greater variety of production control problems. Some of the features discussed are the large screen, t h e low field light, the high sensitivity, t h e stability, the removal of stray light, the noncritical optics, the accessibility, and the scanning convenience. Functional aspects of the instrument have been particularly emphasized in such factors a s economy of operator movement, freedom of eye fatigue, and minimization of maintenance difficulties. Effective Parameter Tests on Spectroscopic Spark Source Units. FREDERICK BRECHAXD JOHN HEIM, Research Laboratory, JarrellAsh Co., Boston, Mass. The quality of a spectroscopic spark source unit is dependent 011 factors additional t o t h e quality of components from which the source unit is made. There are, however, few methods by which t h e effective parameters and energy output of such units may be tested by the spectroscopist. This paper showed t h a t linear relationships on log-log plots exist between the R F ampere output and values for t h e total inductance of t h e circuit, and separately for the capacitance and resistance for successive numbers of breaks in each half cycle. T h e work was done on t h e Jaco Varisource unit which employs a tandem gap of t h e air quenched type. Factors which cause departures from t h e relationships to be presented were also discussed.

V O L U M E 2 5 , NO. 3, M A R C H 1 9 5 3 R . J. UELTModern Diffraction Gratings. DAVIDRICHARDSOX, R . 8 . WILEY,Bausch and Lomb Optical Co., Rochester 2 . N. Y . Z E R , AND

T h e development of a method for producing substantial numbers of exact copies of original diffraction gratings coupled with t h e ability t o rule a variety of sizes and types of such gratings makes i t possible t o supply t h e world demand for gratings. These gratings can be shown to have greater efficiency, longer life, and lower scattered light t h a n the master gratings from which they are made. There is no loss of resolving power or change in the intensity of t h e ghosts inherent in t h e process. Transmission gratings with carefully controlled groove form are now available in a variety of sizes. These gratings are very efficient in t h e blazed region of t h e spertruni and permit t h e consideration of new designs for iristriinients to be used in spectral regions where glass is transparent. Double-Beam Densitometer and Comparator. ROBERT O'B. CARPESTER, Baird .4s\ociates. Inc., Cambridge 38, XIass., ASD J O H X U. WHITE. The White Devclopnient, Corp., Stainford, Conn.

4 double-beam densitometer has been desigtied, with a servo-type automatic balancing system (strip chart recorder optional) and a projertion comparator (magnification lox), The use of a variable aperture, awurately logarithmic, with a range of density 0 t o 3.3, as t h e ultimate standwi~ilfor measurement leads to an instrument wieh a very high degree of a w u r a ~ tability, and simplirity of operation. T h e scale is lineal i n denaity units. T h e two beams transmitted through t h e spectrum plate and t h e variable aperture are alternated onto a 1P21 photomultiplier a t 60 cps. This tube is used in a logarithmic amplifier circuit described by Sweet [>I. H. Sweet, J . Opt. SOC.Amer., 37, 432 ( 1 9 4 i ) ] which provides a servo-loop gain, a stability, and a precisioii of 10.003 density unit, all independent of t h e density being meabured. Hollow Cathode Discharge Tube and Power Supply for Routine Analysis. N. E. GORDOS,JR.,ASD H. D . COOK,Chemistry Department, Atomic Power Division, Westinghouse Electric Corp., Pittsburgh. Pa.

A hollow- cathode discharge tuhe has been developed that eliiriiiiates ground-glais or metal joints that must he sealed with vacuum wax or grease. This discharge tube is of metal conatructiou and is racuum sealed with Neoprene 0 rings and gaskets. T h e advantages of this hollow cathode over those previously described are: its sturdy construction results in a minimum of repairs; the design facilitates cleaning and sample loading: and its adjustable carriage permits mpid and precise optical alignment. A high 7-oltage power supply was described. I t s output voltage is continuously variable from 0 t o 1 kilovolt a t any output amperage from 10 milliamperes to 1 ainpere. T h e power supply is contained in a mobile panel rack cabinet whirh also houses timers for automatirally limiting t h e preburn and expohure periods. Infrared Spectra of Solids and Their Interpretation. R . S. H ~ L Department of Chemistry, Columbia University, New York City.

527 where solubility permitted. These studies iiidivate the presence of only one hydrogen bonded N-H stretching frequency in compounds of type 1 and two such frequencies in compounds of type 2. An investigation of t h e infrared spectra of a high molecular weight homopolyamide (or polypeptide) namely, poly+, L-alanine-has also been undertaken. Infrared spectra d a t a have been obtained on films of pOly-D, L-alanine cast from a variety of solvents under varying conditions of temperature, salt concentration. p H . etc. These results seem t o indicate t h a t films cast from this material may be converted from a predominantly intermolecularly hydrogen bonded structure t o an intramolecularly hydrogen bonded structure and under proper conditions returned t o t h e predominantly intermolecularly bonded state. T h e bearing of t h e above results on protein structures was discussed. Hydrogen Bonding in Crystals and the Nature of t h e Hydrogen Bond. R . C. LORD.\ND R. E. MERRIPIELD, Spectroscopy Laboratory arid Department of Chemistry, -Massachu>etts Institute of Technology, Cambridge 39, Mass. The infrared absorption band anhoviatetl with the stretching frequency of a bonded 0-H or S-H group is sometimes difficult t o identify when t h e hydrogen honding is very strong. T h e bands are ahnormally shifted in frequency, are ununually broad, h a r e low peak intensities. and often hhow several maxima of comparable intensity. Various bands of this sot't h a r e been investigated in crystals of known 0-H-0 bond distances and t h e distances correlated linearly with t h e frequency shift. An interesting type of strong hydrogen bond has also been found in tertiary amine hydrohalides. T h e characteristics of this kind of band, as shown by studies on all four hydrohalides and their deuterium analogs, are their constancy of frequency, breadth, multiple maxima, and large anharmonicity. These features were discussed with respect t o their bearing on the nature of the hyrliogen bond. Statistical Tools in Routine Spectrochemical Analysis. C. H. XORTH,Titanium Division, Research Department, National Lead Co., Sayreville, N. J.; L. E. OLMSTED,Titanium Division, Development and Engineering Department, National Lead Co., St. Louis, Mo., . ~ N DR. D. TOOMEY, Titanium Division, Development and Engineering Dept., National Lead Co., Sayreville, N.J. I n setting u p a spectrochemical method. evaluatioii of t h e n j variables is facilitated by the statistical approach. rlnalysih of variance and factorial design show which variahlea can be dihreaarded and which need t h e most careful control hecause t h e latter iignificantly affect either the mean value or precision of the annlytird intensity ratio. Statistical quality control techniques serve t o reduce t h e frequency of emulsion recalibration or analytical curve restandardization, siuce no effort t o improve either is warranted unless t h e normal random variation is exceeded. Methods were described for detecting changes in emulsion calibration, changes in excitation mnditions, shifts in analytical curves. gross errors in sample excitatiorl or photographic processing which affect only one plate or film, a i d gross errors which affect only one of t h e spectra on a plate or film.

FORD,

T h e changes in spectra t h a t might be observed in going from t h e vapor through the liquid and solid states were discussed. T h e origin of these changes and their utilization in structure studies on t h e smaller and more symmetrical molecules were outlined, emphasizing t h e solid state. I n larger unsynimetrical molecules polarized radiation studies of t h e solids can yield valuable information concerning molecular structure. T h e application of polarization techniques t o solids and t h e interpretation of the results were covered.

New Procedure for Emulsion Calibration. J. S. ~ I J Products Division, General Motors Corp., Dayton, Ohio.

L V E ,

Delco

ELKAN R. BLOUT,Polaroid Corp., Cambridge 39, Mass.

Using suitable masks or a modified Hartrnann diaphragni. inult iple overlapping exposures are made on a plate. T h e densities of various line portions are measured and plotted, and compensation made for excitation variables. D a t a are then subjected to a graphical crossaveraging procedure t o derive t h e gainma curve. T h e method also includes a simple procedure for constructing a gamma nornograph which will permit gamma determination from a aingle exposure, and indicate whether t h e shape of t h e gamma curve has changed. T h e method is entirely graphical; no numerical computations are involved.

T h e determination of t h e molecular structures of proteins may be furthered b y interpretation of their infrared spectra particularly in terms of different amounts and types of hydrogen bonds. Of especial interest in this connection are t h e location and intensity of t h e absorptions due t o N-H and C=O stretching vibrations and N-H deformation frequencies around 3300, 1650, and 1550 cm.-*, respectively. Such absorptions are also observed in amides and polypeptides, and indeed certain such compounds may serve as useful models for t h e study of protein spectra. T h e infrared spectra of secondary amides of two types of dibasic acids have been studied-(l) those compounds such as N,N'-dibenzyl fumaramide where intramolecular hydrogen bonding is unlikely and only intermolecular hydrogen bonds exist because of steric factors, and (2) those compounds such as h',N'-dibenzyl maleamide where both inter- and intramolecular hydrogen bonds m a y occur. T h e above compounds, and related amides, as well a s di-secondary amides.of succinic. adipic, suberic and azaleic acids, have been studied in t h e solid state, and in solutions of nonhydrogen bonding solvents

Panchromatic Spectrographic Filters. RALPH E. QrH.\cIx.iT, EARLE S. BIDGOOD, A N D WALTER L. SAVELL, Laboratory of Advanced Research, Remington Rand, Inc., South Sorwalk, Conn. I n t h e regular operation of a n emission-type spectrograph a range of panchromatic filters is required t o control film exposure without variation of t h e exposure time. A series of simple, stainless steel, wire-mesh screen filters has been constructed t o serve this purpose. After extensive testing of a set of these wire-mesh filters they h a r e been found entirely satisfactory and h a r e been adopted for experimental and routine application in spectrographic analysis. Rugged and easily handled these filters hold their calibrated d u e s for a n indefinite period of time. T h e screen filters are particularly useful in making film exposures t h a t require such short periods of time as t o create the possibility of serious error in measurement of the exposure time period. They also serve admirably as a dependable means of controlling light values in t h e calibration of film negatives.

Infrared Spectra of Model Amides, Polypeptides, and Proteins.

528 Factors Influencing Emulsion Calibration. FRED9.MCNALLY FREDERICK BRECA,Research Laboratory, Jarrell-Ash Co., Boston, Mass.

AND

Forty laboratories have contributed typical experimental d a t a and spectrum plates from which they produce emulsion calibration curves. T h e spectrographs and auxiliary apparatus employed are representative of commercially available apparatus of differing manufacturers. T h e laboratories were not asked t o conform t o a given set of conditions and therefore different laboratories employed different methods for emulsion calibration-i.e., typical of their routine work. A correlation of t h e data submitted has been made, and, in addition, t h e spect m m plates have been re-evaluated employing a single method. T h e results presented include a discussion on t h e effect of slit illuiuination, on photographic processing conditions, on t h e technique of photometry, and on the method of presentation of calibration curves. Improved Calculator for Spectrographic Analysis. A. L. HALLOCarbide and Carbon Chemicals Co., Oak Ridge, Tenn.

WELL.

An improved calculator for reducing the amount of work involved in nialring spectrographic determinations was described. This instrument combines principles of nomography with t h e operations of a slide rule. I t consists of two scales mounted in an aluminum frame so t h a t they may slide parallel t o one another, and also so t h a t distance by which they are separated may be varied. -4hair-line index on a strip of plastic is pivoted between t h e slides, and it may be rotated for the purpose of making measurements. The ratio of the distance the slides are from t h e center pivot is indicated on two other scales. With this arrangement, either plate calibration scales or logarithmic percentage scales may be effectively varied in magnitude, one relative t o t h e other, and also a slide rule operation may be performed on the transformed scale. This calculator differs from a n y previously described in the literat u r e in t h e following respects: A method is used for varying a logarithmic scale so t h a t it' is equal to, and replaces, all working curve scales, and i t is used with a plate calibration scale and a background correction slide rule for obtaining t h e concentration of a n y element in a sample directly from t h e microphotometer data. As t h e need for preparing a separate Jcale for each working curve is eliminated, it is practical t o use this calculator universally for all spectrographic analyses. New Infrared Variable-Thickness Cell. W.ALEXPATTERSON AND C H ~ R L EG. S BEARCE, Baird Associates, Inc., Cambridge 38, Mass.

.A new variable-thickness cell has been developed. This was designed especially for use on t h e Baird Associates infrared spectrophotometer but can be used on other infrared spectrometers. Features of t h e cell are a Teflon bellows; a cam for varying t h e thickness; an over-all length dimension of only 6.5 em.; and thickness adjustments by a single micrometer screw. T h e range of cell thickness in t h e present model is from 0 t'o 2 mm. and a setting of 1 division on t h e micrometer screw represents 0.002 mm. of thickness. A high degree of reproducibility in thickness settings has been obtained. Continuous Analysis of Liquids. GLENS SMITH,Process Controls, Division of Baird Associates, Inc., Cambridge 38, Mass. A nondispersive infi.ared instrument has been developed for t h e continuous analysis of liquid streams. D a t a were presented outlining t h e construction and operating details of t h e instrument. Several specific applications including t h e measurement of water in liquid hydrocarbons were discussed with appropriate calibration data. Tri-Hon Analyzer, a n Infrared Absorption Instrument for Continuous Gas Analysis. E. H . WOODHULL, J. L. BORDEN,A N D T. FLYNS, T h e Perkin-Elmer Corp., Norwalk, Conn. A nondispersion analyzer for continuous recording of a process stream variable is described in detail. T h e instrument is of the basic double-beam type with conventional sensitizing, compensating, and filter cells, except t h a t a third radiation beam with a servo-driven trimmer has been added t o achieve a true radiation null a t t h e selective gas filled detector. This detector has been made insensitive t o vibration by dynamic balancing of gas and condenser microphone membrane masses. T h e selectivity of t h e instrument and a typical application were described. Bichromator Analyzer. A Dispersion Instrument for Continuous J. G . ATProcess Analysis in the Chemical Plant. A. SAVITZKY, WOOD, R . G. PILSTON, AND G . F. WALLACE, T h e Perkin-Elmer Corp., Norwalk, Conn. Quantitative analysis of plant streams is performed by obtaining t h e ratio of t h e transmission a t a sample and a reference wave length. T h e two wave lengths appear simultaneously at t h e exit slit of t h e dispersion system through the use of a split Littrow mirror. T h e

ANALYTICAL CHEMISTRY energies are compared by chopping a t a n image of t h e Littrow mirrors and are kept a t null balance by meails of a servo-operated wedge. I n order t o achieve t h e required stability for reliable long-term performance under plant conditione, radical departures have h e n taken from laboratory spectrometer practice. Fixed, cemented optical element, three-dimensional box construction, rather t h a n t h e familiar flat bed, and t h e almost complete elimination of adjustments are among t h e innovations. Comparison of Perkin-Elmer Models 12-C and 21 Infrared Spectrometers to Evaluate Their Precision in Routine Use. EUGENE CKILDERS, Belle Works Technical Section, E. I. du Pont d e Nemours & Co., Inc., Charleston, W. Va. The inherent instrument cmharacteristics of the Perkin-Elmer Model 12-C and Model 21 infrared spectrometem were evaluated from t h e standpoint of reproducibility, linearity. and simplicity of operation. The objective was instrument utility on a day-to-day basis in plant control laboratories where the instruments are used m-ithout modification t o perform routine quantitative measurement. The study did not encompass modification of the instruments for research purposes. An adjunct t o this study was t h e evaluation of the piecision of a quantitative infrared method used routinely t o determine t h e concentration of cyclohexanone and cyclohexanol in a cyclohexane solution of t h e two components. T h e precision of t h e method was evaluated in terms of a single analysis on one sample, routine use in one laboratory, and routine use in more than one laboratory. New Micro Absorption Cell. G. E. MOOREA N D H. D. DEVERALX. Polychemicals Department, E. I. d u Pont de Nemours & Co., Inc.. Wilmington, Del. T h e use of micro absorption rells of long path length and low total volume is essential in many ultramicro colorimetric procedures. I n t h e determination of milliniicrogram amounts of metals through colorimetric methods, t h e color may frequently be developed in solutions having a final volume of 1 ml. or less. Cells of t h e design suggested by Kirk and his coworkers are available commercially. Difficulties in filling and positioning these cells in a spectrophotometer led t o t h e consideration of a new design which would eliminate these problems . T h e body of t h e new cell is a tube of Teflon tetrafluoroethylene resin sheathed in a stainless steel jacket. T h e cell is 7.2 cm. in length with a total volume of 0.9 ml. Quartz windows are held against t h e body by steel caps which screw over t h e body. T h e cell will fit either t h e standard cell holder of t h e Cary spectrophotometer or t h e special micro cell attachment of the Beckman instrument. Typical results obtained with t,he cell in both t h e visible and ultraviolet regions of t h e spectrum were given. Reproducibility of Measurements Made on a Cary SpectrophoE RL. B. tometer and its Log Density Attachment. J. L. F O R ~ T NAND ROGERS,Department of Chemist.ry and Laboratory of Nuclear Science and Engineering, Massachnsett~Institute of Technology, Cambridge, Mass. A performance study has been made of the Cary recording spectrophotometer and its log density attachment. T h e effect of t h e two major variables, t h e slit and t h e scan rate, on t h e reproducibility of t h e spectrum of benzene in isoortane was investigated. T h e standard deviation at a scan rate of 20 A. per second was 0.004 optical density unit N for t h e reproducibility of t h e peak to minimum distances on t h e density recorder and 0.003 on t h e log density recorder. S t lower scan rates t h e standard deviations decreased for both recorders. T h e effect of an optically dense blank is purely a matter of increased spectral slit width as long as the slit mechanism is able to respond t o rapid changes in optical density. Studies of t h e determination of toluene in different concentrat,ions of benzene showed t h a t t h e speed of response is sufficient t o cope with a moderate concentration of benzene in t h e blank a t scan rates of 1 t o 5 A. per second. A log density plot of a spectrum should be independent of the concentration of the solute. The reproducibility of t h e spectrum of toluene on t h e log density recorder for a series of different concentrations was found t o have a standard deviation only twice t h a t for a single concentration. Absorption Spectra of Organic Vapors. R. A. FRIEDEL, Synthetic Fuels Research Branch, Bureau of Mines, Bruceton, P a . Liquid compounds usually are examined spectroscopically as liquids

or a s solutions. Vapor spectra have not been used quantitatively b e cause of t h e inability t o measure low pressure accurately. T h e selffilling micropipet method for introducing liquid into t h e mass spectrometer through a sintered disk [Friedel, Sharkey, and Humbert, ANAL.CHEM..21, 1572 (1949) J has been modified and applied t o this

V O L U M E 25, N O . 3, M A R C H 1 9 5 3

529

aroblem. As little as 0.001 nil. of a volatile liquid can be vaporized into a n evacuated infrared or ultraviolet cell with a reprodubility of 1%. No stopcock grease, wax, or rubber tubing need he in contact with t h e vaporized sample. l d v a n t a g e s for analysis of volatile compounds are: simplicity of :echnique, elimination of solvent, production of vapor state fine structure which promotes easier identification, limited ability t o run infrared spectra of aqueous solutions, and elimination or diminution oi complex formation, such as alcohol-aldehyde complexes. In addition, some advantages of this technique for theoretical inyestigations are: Vapor pressures are measured accurately: infrared .studies of pressure broadening effects of two vaporized liquids can be carried out: and vapor phase reactions can be studied, with incremental addition of reactants.

concentration accurately. T h e elements are determined in t h e range of 1 t o 20 p.p.m. in a 2% beryllium solution. Coniparison was made between acetylene and hydrogen flames and betw-een t h e standard blue sensitive phototube arid the photoniultiplier attachment.

Spectrochemical Analysis of Aluminum Alloys Using Molten Metal Electrodes. LEOD . FREDERICKSON, JR.,A N D J. RAYNOR CHURCHILL, .Uuminum Research Laboratories. Aluminurn Co. of .\merica, New Kensington, Pa.

Applicability of Controlled Atmosphere Excitation to Spectrographic Methods of Analysis of Aluminum Alloys from Compacted Chips. S. GOLDSPIELAND F. BERNSTEIN,Material Laboratory, New York Kava1Shipyard, Brooklj;n, N. Y.

l l t h o u g h spectrochemical analysis plays an i tiiportant role in t h e 2roduction of aluminum alloys, certain variables in t h e conventional irocedure remain which are associated with t h e metallurgical history of t h e samples analyzed. Examples include variations in excitation zharacteristics, differences in grain size and distribution of constituents within and between grains, as well as porosit,y and shrinkage rracks. Differences also occur between samples which have been forged, rolled, or extruded, and the spectral behavior is markedly influenced by annealing, heat treating, and working. These variables may be eliminated by employing a molten electrode of t h e material to be analyzed, and using spark excitation. Description was given of several methods which have been investigated for t h e simultaneous melting and spectral excitation of aluminum alloys, including “sourcepower melting,” auxiliary arc melting, and several types of furnace melting. Preliminary work indicates t h a t induction melting m a y .satisfy t h e melting requireinelits and provide favorable electrode Seometry. Success of t h e method is predicated upon a close control of all physical parametera in a carefully timed sequence of melting and sparking.

For further improvement of reproducibility of intensity ratios of constituent ws. aluminum lines, noted when argon atmospheres were used in t h e spark excitation of aluminum alloy (illcoa 245) chip compart [“Controlled Atmosphere Applied in t h e Spectrographic Analysis of Aliiininum Chips,” S. Goldspiel and F. Bernstein, AppZied Specf~osciipy6 , (August 1952)], a study was made of t h e effects of chip size, icsrbon bonding, shape of pellet. sample pellet t o sample pellet aiid t o carbon electrode forms. T h e results show t h a t unbonded, flat-tipped pellets to carbon counterelectrodes produce t h e most de5irahle combination. Chip size does iiot have a significant influence on the results. .Innlytical working curves for manganese, magnesium, and silicon corering t h e percentage ranges found in Alcoa types 14S, l T R , A17S, and 245 were obtained for flat-tipped pellet versus pellet and versus carhon electrode forms. T h e slopes of all curves for t h e latter combinations are essentially t h e same as those for working curves o b tained by t h e use of t h e conventional solid aluminum disk vs. carbon counterelectrode in air. Lateral shifts of curves for pellets in argon are in a direction indicating a decreare in energies availahle t o neutral atom transitions. Standard errora of estimate, except for manganese, are nearly twice those foi, the conrentional technique indicating need of additional improvement i n the pellet form and size for more reproducible sample material.

Evaluation of Source and Photographic Variations in the Spectrographic Analysis of Low Alloy Steels. D. L . FRYAXD T. P. SCHREX E R , Research Lahoratories Division, General Motors Corp., Detroit, Mich. The spectrographic analysis of *teels for receiving inspection is ioniewhat more difficult t h a n the analysis for. production control. This paper presents t h e effects on intensity ratios and on analytical wrves in a point-to-plane method of source variations, analytical ?air selection, and t h e variation due t o emulsion irregularities. 3ource parameters have been measured and energy st.udies made for :tie numerous source conditions tried. Determination of Acid-Soluble Aluminum in Steel. C,, V. Roow:Y, C‘olumhia-Geneva Division, U. S. Steel Co., Geneva, Utah.

I simple spectrographic procedure for t h e deterniination of acid soluble aluminum in carbon steel was described. After solution and separation is efyected in t h e conventional manner, the holution coutaining t h e acid soluble alumintun is introduced into t h e spark gap ;tirough t h e use of a rotating electrode. Sparklike conditions on a multisource hare heen u m l to cover t h e :.ange from 0.005 t o 0.12%. Determinations in t h e range from 0.03 to 0.06% were found t o agree with chemically determined values within 0.002%. T h e spectrographic determinations are believed t o be more reproducible, faster, and more economical t h a n those found by wet methods.

*

Line Width Method of Spectrochemical Analysis. D. J. HUXT .WD D. L. Tmnf.4, hfound Laboratory, Monsanto Chemical Co.. Miamisburg. Ohio. I n most cases intensities of lines are used as a guide t o concentration in quantitative spectrochemical analysis. I n recent years t h e widths of lines have also been shown t o be indicative of concentration. An example of this less publicized method was demonstrated in t h e quantitative analysis of trace metals in a bismuth matrix. A comparison of several variations of t h e line width method and t h e conventional intensity ratio method was presented. Determination of Sodium, Potassium, and Lithium in Beryllium Solutions by Flame Photometry. H. R . MULLINA N D T. P. SHEEHY, l t o m i c Energy Commission, New Brunswick Laboratory, New Brunswick, N. J.

A flame photometric method for t h e determination of lithium, potassium, and sodium in beryllium solutions was described. Since beryllium in solution has a tendency t o suppress t h e emission of other elements in t h e flame, it was necessary t o control t h e beryllium

Production Control Quantometer in the Secondary Aluminum Industry. M. E. SLAQEL,G. S.Reduction Co., E a s t Chicago, I n d .

B brief discussion was given of why this instrument was purchased, costs, and t h e resulting savings. What it accomplishes in t h e production schedule was described briefly and different working curves were given for individual elements and t h e manner in which routine samples are handled.

Routine Spectrographic Analysis of Impurities in Cadmium, Bismuth, and Their Alloys. G. R. PETERSON AND E. W. CI-RRIER, Federal Telecommunication Laboratories, S u t l e y , N. J.

A spectrographic method was given for the quantitative determination of copper, iron, lead, silver, thallium, and tin in cadmium, bismuth, and their alloyq. T h e samples are dissolved in nitric acid. Graphite and palladium are then added. The samples are evaporated t o dryness and heat,ed over a burner until the nitt,ic fumes are rompletely removed. T h e dry graphite mixture is ground in an agat,e mortar and packed into cupped graphite electrodes. T h e samples are excited in a d.c. arc; t h e spectrum is recorded on process panchromatic film using a Littrow niodel quartz spectrograph. T h e nominal range covered hy thi. method of analyhip is from 5 to 50 part> per tiiillion. Infrared Spectra of Aromatic Compounds ; Evidence for Intramolecular Hydrogen Bonding between Substituent Groups and Ring Hydrogens. M. hf.lRGosHEb A N D T. A. FASSEL, Department of Chemistry and Institute for .Itomic Research. Iowa State College, ilmes, Iowa. T h e iufrared ahsorption spectra of -ome aromatic compounds have been studied between 625 and 900 em.-’, where these compounds have C-H bending vibrations chararteristic of the number and position of substituents. The band structure in this region was found, in many cases, to be considerably diffwent from what is to be expected for t h e particular arrangement of substituents, especially for nitro compounds and carboxylic acids, esters. and salts. T h e deviations are explained by (1) a strong absorption hand in this region for many of these compounds t h a t is apparently not due t o thc usualC-H bending vibration, and ( 2 ) a consibtent shift of the C-H bending vibrations t o higher frequencies, caused by bonding of one or more of the ring hydrogens t o an electronegative atom of t h e suhstituent group. Intermolecular distances from x-ray diffraction studies and variations in t h e absorption spectra with variations in t h e structure of t h e compounds are given as evidence for the presence of this hydrogen bond. Graphical “Absorbance-Ratio” Method for Rapid, Two-Component, Spectrophotometric Analysis. ROBERTc. HIRT. ~ N DFRANK T. KING,.hnerican Cyanamid Co., Stamford, Conn.

4 simple, rapid, graphical method for t h e spectmphotometric analysis of two-component systems is obtained by using t h e ratio of

ANALYTICAL CHEMISTRY

530 observed absorbance readings at two selected wave lengths. One of these wave lengths is selected, if possible, a t t h e “isoabsorptive” point (where t h e values of t h e absorptivities for the t,wo pure components are equal): this permits a straight-line plot of t h e ratio of t h e observed absorbances versus relative composition, as may be derived from Beer’s law. T h e total amount of t h e two components is obtained by use of t h e Beer’s law equation a t t h e isoabsorptive point. Lack of an isoabsorptive point requires t h e plotting of a curve from a simple function of t h e absorptivities of t h e pure components and relative composition. Criteria for the selection of t h e wave lengths were discussed, and some examples were presented. T h e method is applicable t o ultraviolet and visible spectrophotometric data (and t o infrared d a t a when absorbance values are known), and it may be extended t.o three-component systems. Infrared Spectra of the Methyl Chlorosilanes. A. LEE SMITH, Spectroscopy Laboratory, Dow Corning Corp., Midland, Mich. T h e infrared spectra of t h e methyl chlorosilane series SiClr through SiMe4 have been obtained in t h e gas phase over t h e range 2 t o 25 m u using calcium fluoride, sodium chloride, and potassium bromide prisms. T h e spectra are compared with Raman data on these compounds, and vibrational assignments are suggested. Quantitative Determination of Dithiocarbamates and Thiuram Sulfides. C. L. HILTON,General Laboratories, U. S. Rubber Co., Passaic, N. J., AND J . E. NEWELL,X’augatuck Chemical Co., Division U. S.Rubber Co., Naugatuck, Conn. T h e method described has been developed for t h e determination of t h e zinc dithiocarbamates and thiuram sulfides in rubber. It involves extraction from t h e rubber stock by means of ethanol. decomposition of t h e accelerator to form carbon disulfide, distillation of t h e carbon disulfide into an aqueous dimethylamine solution, and spectrophotometric analysis of t h e resulting mixture. T h e dithiocarbamates are decomposed by heating in ethanol acidified with phosphoric acid. The thiuram sulfides, on t h e other hand, must first be reduced by means of sodium hydrogen sulfite. I n view of the discovery t h a t thiuram sulfides are converted into dithiocarbamates during vulcanization, t h e method has been developed in such a way t h a t t h e dithiocarbamates and t h e thiuram sulfides can be determined separately. T h e analysis could then be used as a measure of t h e degree of conversion. When t h e accelerator in t h e sample is subjected t o extraction and decomposition in acidulated alcohol, the zinc dithiocarbamate series decomposes. T h e liberated carbon disulfide is distilled into a n excess of dimethylamine, which is optically transparent in t h e region from 260 t o 300 mp. T h e product formed has absorption maxima a t 253 and 287 mp, and minima a t 225 and 270 mp. Inasmuch a s there are interferences below 280 mp, only t h e absorbance readings a t 287 m p were utilized. After t h e determination of t h e dithiocarbamates has been completed, t h e residue is neutralized with dilute sodium hydroxide and an aqueous solution of sodium hydrogen sulfite is added. T h e distillation and determination of t h e liberated carbon disulfide are then repeated. T h e method described within shows a n accuracy within *2% for t h e pure accelerators and a precision &l’%for t h e accelerators in rubber stocks. Ultraviolet Analysis of Isomeric Cresol Mixtures. G. P. CARNEY J. K . SANFORD, Research Laboratory, Barrett Division, Allied Chemical & Dye Corp., Philadelphia, Pa.

AND

A simple, rapid, ultraviolet method for analyzing mixtures of a n y two or all three isomeric cresols in solution in iso-octane is based on t h e absorptivities of t h e isomers a t 2774, 2728, and 2868 A. T h e largest error in the determination of each component of fine synthetic mixtures was about 1.5% (absolute). Infrared Study of 8-Hydroxyquinoline and Some of I t s Metallic Chelates. R. G. CHARLES(Westinghouse Research Laboratories, Pittsburgh, Pa.), L. E. HILLIARD,HENRYFREISER, AND R. A. FRIEDEL (U. S.Bureau of Mines, Bruceton, Pa.), Chemistry Department, University of Pittsburgh, Pittsburgh, P a . T h e infrared absorption spectra of 8-hydroxyquinoline and of a number of its metallic chelates [copper(II), aluminum(III), nickel( I I ) , cobalt(II), zinc(II), lead(II), cadmium(I1). lanthanum(III), manganese(II), magnesium(II), chromium(III), iron(III), gallium( I I I ) , indium(III), calcium(II), uranium(VI), sodium(I), and potassium(1) ] have been obtained by a mineral oil mull technique. An analysis of these spectra has shown t h a t , while t h e spectra of all t h e metallic chelates are similar t o each other and t o t h e reagent itself, the exact position of several of t h e absorption bands is dependent on

t h e metal present. For t h e divalent transition metal chelates htudied. a direct relationship has been found between t h e position of an absorption band a t about 9 microns and t h e stability of t h e chelate a s determined potentiometrically in a dioxane-water solution. Relationships have also been found between t h e position of this same absorption band and t h e ionization potentials of certain of t h e metal atoms. An attempt has been made t o interpret these results in terms of the structures of the respective complexes. Technique for Obtaining Infrared Spectra of Some Viruses. D. F. KOESIG,M. E . \T.