V O L U M E 2 5 , NO. 1 2 , D E C E M B E R 1 9 5 3 iwndix contains a ready reference t o methods for t h e rapid analysis of b a t h samples, literature references from 1930 (including books published in English), a glossary of chemical, physical, a n d inctallurgical terms, a n d lists of British chemical standards. Section I contains chapters on available techniques a n d their characterizing the nature of the hydroxyl group in compounds such !1111yI O synthetic samples containing 50 t o 200 mg. of sulfate. as hydroxy esters, ether alcohols, and others. T h e test was being applied to a series of glycols. amino alcohola, amines. a n d substituted Volumetric Determination of Alumina in Bayer Process Liquors. benzenes and naphthalenes. . ~ N DALTONE. MCLAUGHLIN, Kaiser Aluminum ROBERTR . PHILLIPS N-Chlorosuccinimide, iV-iodosuccinimide, and dibromodimethyl,:nd Chemical Corp., Bat,on Rouge, La. hydantoin were also being investigated as classification reagents. \‘L
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The gral-imetric determination of alumina in Bayer process liquors Volumetric methods involving precipitation of K3.41Fe are not acceptably accurate for plant liquors containing silica. T h e following method, a synthesis o f methods already known, was convenient, rapid, and acceptably accurate. Silica and phosphate interference was inappreciable if iliese substances were not present in rather large amount, but -illfate should be absent or low. -1solution o i alumina in excess hydrochloric acid was sampled in luplicatc aliquot>. To one aliquot was added a large excess of neutral jJotaAum oxalate; titration with standard base then determined the free acid. Under proper conditions, t h e p H of the end point varied vnly slightly, and the end point was readily noted by t h e use of a mixed indicator. To the duplicate aliquot was added a n excess of neutral barium chloride and Rochelle salt solution. T h e result was the apparent liberation of three protons per aluminum atom. T h e acid thus produced was conveniently titrated t o a sharp end point with phenolphthalein. T h e difference between the two end points was stoichiometrically related to alumina content. Caustic soda and total ;oda. quantities of interest in Bayer process control, were also easily determined. is lengthy and usually of no great accuracy.
Determination of Epoxides with Sodium Sulfite. J. DONALD Sw-aN. .Jefferson Chemical Co., Austin, Tex. -4method for determining epoxides based on their reaction with sulfite was described. Titration of the liberated
. U ~ I I C O U S sodium
Analytical Studies of Some Acyloin Oximes. HANSA. SUTERA N D PHILIPW. WEST, Louisiana State UniverJity, Baton Rouge, La. The unusual solubility relationships of t h e copper salts of the alpha isomers of acyloin oximes have been investigated. Based on these studies, a polymeric structure for these copper salts was proposed. T h e following alpha-isomers of acyloin oximes were examined: benzoin oxime, 2,2’-furoin oxime, phenylbenzoin oxime, methylbenzoin oxime, 2,2’-thenoin oxime, a-hydroxyacetophenone oxime, and a-hydroxyisobutyrophenone oxime. Of these compounds only benzoin oxime had been previously studied from the standpoint of their use in analytical chemistry.
Microscopic Fusion Study of 2,4,5-Trichlorophenoxyacetic acid E t h y l Corp., and Related Compounds. CLAUDEJ. .-IRCENEAUX, Baton Rouge, La. Microscopic fusion techniques were applied t o a study of 2.4,5trichlorophenoxyacetic acid and six related compounds. This was done in order to obtain fundamental crystallographic data and rapid methods of characterization for the following compounds: 2,4,5trichlorophenoxyacetic acid: 5-methoxy-2,5-dichlorophenoxyacetic acid; 2,4,5-trichlorophenol; the sodium and potassium salts of acid: and trichlorophenoxyacetic acid ; 2,3,6-trichlorophenoxyacetic
ANALYTICAL CHEMISTRY
1932 2,5-dichlorophenoxyacetic acid. Furthermore, simple and rapid qualitative fusion methods of detection have been developed for the sodium and potassium salts of 2.4,5-trichlorophenoxyaceticacid in the commercial product. Theory of Electrolysis a t Controlled Current in Unstirred Solution. Experimental Study of Potential-Time Curves. PACLDELhH.4Y A N D C . ~ L V IC. N M A T T . ~Louisiana ~, State University, Baton Rouge, La. Experimental methods for the precise recording of potential-time curves are described and applied to various electrode processes. T h e theoretical treatment of reversible electrode processes is verified in the cases of the reduction of ferricyanide, thallous, and cadmium ions. The properties of potential-time curves obtained by reversing the current a t the transition time are also in good agreement with theory. The features of experimental potential-time curves for t h e irreversible reduction of oxygen, nickel(II), and cobalt (11) in various electrolytes also agree well with theory. The analysis of potentialtime curves for t h e reduction of chromate ion in 1 Jf sodium hydroxide indicates the occurrence of a stepwise process. Potentialities of the constant current method in the study of electrode processes are discussed, and applications to analytical determinations are briefly mentioned. Experimental data determined by the present method are used in the verification of the theory of irreversible polarographic waves previously developed. Determination of Moisture in Salts by the High Frequency Method.
and in some cases large potential changes a t the end point. A technique enabling the use of this solvent when titrating weak primary and secondary amine bases was described. Coordination of Instrumental Analysis with Other Analysis Methods. JOHN T. WILEY,Texas Co., Port Arthur, Tex. I n laboratories where analytical instruments are in use questions arise as to what instrument or instruments should be used for a particular sample or if instrumental methods are desirable. This is especially true of samples t h a t are submitted with only the notation "identify" and without additional information as to source or possible constituents. A fairly definite program of analysis for such samples has been established t h a t expedites their analysis by taking advantage of modern instrumentation and a t t h e same time not losing sight of the value of other analytical methods. Samples are divided roughly into two classes, hydrocarbon and nonhydrocarbon samples, except in t h e case of gases, where no division is made. T h e samples are then redivided as to whether liquid or solid. The samples are then observed for general appearance and in the case of solids examined microscopically. Procedure from this point is dependent on the results of their examinations and other factors which were discussed. Apparatus for Determination of Sulfur in Petroleum Products by the Lamp Method. HOWARD HOPKINS, Pawhuska Research Laboratory, Pawhuska, Okla.
FREDW.JENSEN AND M. B. BURTON, JR., -4.& M. College of Texas. College Station, Tex. The purpose of this research was to develop a rapid, simple. and accurate method for the determination of moisture in salts. The apparatus consisted of a 10-megacycle Clapp oscillator with a sample column placed in series with a diode rectifier and a d.c. microammeter. The device was equipped with a temperature compensator. Studies were made on sodium chloride and ammonium nitrate. Fifty-gram samples of the salt mixtures containing varying amounts of moisture were agitated for 5 minutes with a mixture of 1,4-dioxane and methanol. After settling or centrifuging, the liquid was introduced into the sample column and the readings were made on the microammeter. During the stirring process a n equilibrium is set up between the moisture in the salt and the moisture in the solvent. With increase in moisture content in the salt the amount of moisture extracted by the solvent also increases. Since t h e solvent is in all cases saturated with salt, the conductance of the solvent increases with increase in moisture content. With the correct concentration of 1,4-dioxane and methanol the response is linear. T h e instrument showed very good accuracy and reproducibility, excellent time stability, and temperature compensation. The time required for a single moisture determination was on the order of 10 minutes. Determination of Water in Alcohols by a n Indirect Conductivity CHARLESM. HUDGINS,JR., A N D Method. C. KINSEY HANCOCK, R~LPH E. ZERWEKH,JR.,Texas Engineering Experiment Station, College Station, Tex. Uaing methyl and ethyl alcohols, studies of alcohol-acetone-watersaturated sodium chloride systems show t h a t the conductivity is nearly linear with the water content over the range of 0 to 10% water. Linearity can be approached more clearly by increasing the acetone concentration, but a parallel decrease in sensitivity occurs. T h e optimum acetone concentration is about 30%. The procedure requires about 15 minutes and may be used to determine water in methyl and ethyl alcohols. T h e application of t h e method t o the determination of water in other materials is of considerable interest and encouraging results have been obtained in the determination of water in soils and in sucrose solutions. Acetic Anhydride in Nonaqueous Titrimetry and I t s Role in the Determination of Sulfuric Acid Catalyst in Ethanol Esterification Mixtures. A. F. GREYILLION,Carbide and Carbon Chemicals Co., Texas City, Tex. The use of acetic anhydride in nonaqueous titrimetry has been extended beyond its employment as a dehydrating agent. It has been successfully used in the determination of sulfuric acid catalyst in ethanol esterification and a study of the influence of other solvents in the mixture conducted. I n addition, acetic anhydride has been used as a solvent for the titration of a number of weak bases. Some pyridines, amines, and ureas have been titrated with considerable sharpness of end point
An apparatus has been developed which will determine the sulfur content of petroleum products, ranging from liquefied petroleum gases through Diesel fuels, simultaneously and with equal facility. Very precise control over the sample combustion can be obtained throughout the determination, and once started the samples require a minumum of attention. The sulfur is determined volumetrically, and these values are closely comparable with the gravimetric values. T h e results obtained with this apparatus equal or surpass those obtainable with similar apparatus and methods, and the degree of control over sample combustion possible with this apparatus far surpasses that obtainable upon other lamp sulfur apparatus. Radioactive Tracers a s Adsorption Indicators. R . B. ESCUE AND NEWVY.~N P. BULLOCH,North Texas State College, Denton, Tex
A progress report on t h e use of P32and 113' tracers to follow the course of precipitation titrations. T h e adsorption of tracers is affected by excess titrant, and the radioactivity of the tracer is follo=-ed by a G-M tube in contact with the solution. The specific case of adsorption on barium sulfate and the possibility of determining sulfate ion by volumetric precipitation were discussed. Use of Nuclear Techniques in Analytical Chemistry. G. W. LEDDIS. A. RETSOLDS,Oak Ridge National Laboratory, Oak Ridge, Tenn. COTTE ASD
This paper introduced the application of the unique properties of nuclear particles to analytical chemistry problems. Of primary interest are the properties of these nuclear particles and their interactions with matter. Some of these interactions, especially those involving neutrons, have been found useful as techniques for chemical analysis by induced radioactivity (activation analysis), neutron transmission, and neutron absorption. A general discussion of each method, the theoretical sensitivities, and present applications were presented. I n addition to these techniques, the method of analysis by radioactive tracers was discussed. Determination of Trace Elements in Crude Oils and Distillation Products by Radioactivation Analysis. G . W. LEDDICOTTE AND H. A. MAHLYAS,Oak Ridge National Laboratory, Oak Ridge, Tenn. The nuclear reactions which occur in the Oak Ridge National Laboratory graphite reactor now form the basis of a unique analytical service for determining trace element concentrations in many different materials. The method of radioactivation analysis, its sensitivities of detection, and applications were reviewed. Special attention was directed to the determination of trace element concentrations in crude oils and distillation products by neutron activation analysis. Trace amounts of arsenic, copper, chromium, iron, mercury, nickel, sodium, and vanadium in crude oils and distillation products have been determined by this method of analysis. Nuclear data, method of irradiation, processing of samples after irradiation, and type results obtained in the assay of these materials were presented.
V O L U M E 25, NO. 1 2 , D E C E M B E R 1 9 5 3
1933
Determination of Trace Elements in Grass and Grain by RadioA N D G. W.LEDDICOTTE, Oak activation Analysis. H . A. MAHLMAN Ridge National Laboratory, Oak Ridge, Tenn.
Electromagnetic Isotope Separation of the Palladium, Platinum, and Rare Earth Elements. C. P. KEIM,Oak Ridge National Laboratory, Oak Ridge, Tenn.
T h e usefulness of nuclear techniquea involving induced radioactivity by neutron irradiation-Le., neutron activation analy3isin determining trace elements in grass and grain was discussed. Pertinent nuclear data, method of irradiation, processing of samples after irradiation, and typical results obtained in t h e assay of samples mere reviewed. So far, neutron activation analysis has been applied t o the determination of trace concentrations of cobalt, copper, iron. manganese, molybdenum, strontium, and zinc in rye grass and corn.
T h e electromagnetic separation of isotopes has now been accomplished with most of those elements having naturally occurring isotopes. I n recent months, in addition t o maintaining a stock of enriched isotopes for research, progress has been made in processing some of the more difficult elements. For example, t h e palladium and platinum elements do not have stable compounds which can be vaporized in t h e ion source. Also, the rare earth elements must he chemically separated to provide charge material for the mass spectrograph isotope separations. Palladium and platinumlike metals have been heated by electron bombardment to as high as 2800° C. t o provide sufficient vapor in t h e calutron ionization chamber for isotope separation. T h e rare earths are being separated chemically in tributyl phosphate-nitric acid exchange columns to provide mass spectrograph charge materials.
Isotope Effect Study of the Pinacol Rearrangement. WAYNECARof drkansas, Fayetteville, A4rk.
R I C K . ~ N DARTHURFRY. University
1,1,2,2-TetraphenyletIiyleneglycol-l-Cl4 has been prepared and allowed t o rearrange t o l,l,l-triphenylacetophenoneunder se\-eral different sets of reaction conditions. T h e ketone was degraded to triphenylmethane and benzoic acid. I n all cases these two compounds were found t o have the same molar activity within experiment.al error, indicating t h a t there had been no intramolecular isotope effect in t h e rearrangement. These results show t h e improbability of some of t h e detailed reaction mechanisms which have been considered for t h e reaction, but are consistent with t h e postulation t h a t t h e pinacol rearrangement is a completely concerted reaction.
Use of Carbon-14 in a Competitive Reaction Rate Study. CHARLES T. LESTERAND Gus A. ROPP,Oak Ridge National Laboratory, Oak
Determination of Tritium by Radioautography. D. E. BEISCHER, U. S. Naval School of Aviation Medicine, Pensacola, Fla. The isotope hydrogen-3 offers a convenient way to label many inorganic and organic compounds. T h e possibilities and limitations of a quantitative determination and localization of t h e labeled molecules by radioautography were discussed. Effective use was made of tritium-labeled stearic acid monolayers a s secondary radiation standards. Based upon results of this study recommendations for the radioautographic procedure and the choice of t h e photographic material were made. Examples of t h e use of t h e method in surface chemist r y were presented.
Ridge, Tenn. hIaleic-l-Cl‘ anhydride(1) was synthesized from sodium cyanideby a modification of the method of Nystrom, Loo, and Leak [ J . A m . Chem. Soc., 74,3434 (1953) 1. Samples of the anhydride were used in three Diels-Alder reactions a t 25’ C., with t h e dienes 1phenyl-1,3-butadiene(II), l-(p-methoxyphenyl)-1,3-butadiene(III), and l-(pnitrophenyl)-1,3-butadiene(IV). T h e three reaction mixtures were of t h e following compositions in benzene solutions:
I with a large excess of an equimolar mixture of I1 and I11 I with a large excess of an equimolar mixture of I1 and IV I with a large excess of an equimolar mixture of I11 and IV B y analysis of t h e product mixtures using carbon isotope dilution technique, t h e relative values of the specific reaction rate constants 3l i > ~ ~ - N O Z . Although for t h e three dienes were shown to be j Z - 0 ~ ~> t h e measured ratios did not show a close fit to the Hammett equation, t h e results are in accord with a n ionic mechanism for these DielsAlder reactions. I n view of the high polarizability of such dienes as those used here, a close fit to a Hammett equation should, perhaps, not he expected.
Synthesis of I,Z-Dihydr0-3,6-pyridazinedione-3,6-C~~.J. GRAY DINWIDDIE, JR.,AND JOHW A. PORTER, Clemson Agricultural College, Clemson, S.C. T h e process was described by which barium carbonate containing carbon-14 is converted into 1,2-dihydro-3,6-pyridazinedione-3,6CI‘, the cyclic hydrazide of maleic acid. Intermediate compounds in the synthesis include potassium cyanide, succinic acid, dibromosuccinic acid, fumarir acid, maleic acid, and maleic anhydride.
One-Step Preparation of C14-Cyanide from Barium Carbonate-C”. J. K . JE.WES, Texas Research Foundation, Renner, Tex. The importance of cyanide in the synthesis of organic compounds labeled with isotopic carbon requires t h a t it he made available in high yields by simple and inexpensive procedures starting with barium carbonate. Methods have been described for t h e conversion of alkali carbonates t o cyanide, but each has its own limitation. A procedure has been developed whereby barium carbonate can be converted t o sodium cyanide in one step by heating barium carbonate, zinc dust, and metallic sodium in a stream of anhydrous ammonia which had passed over hot iron. Iron seemed to have a n important role, in t h a t it catalyzed t h e decomposition of ammonia t o give nitrogen gas and other “active” forms of nitrogen which were essential in the reaction. T h e yields in this laboratory were quantitative. T h e specific activity of t h e labeled cyanide remained unchanged from t h a t of the carbona,te which was used.
Gamma-Ray Spectroscopy in Analytical Radiochemistry. BERND KAHNA N D W. S. LYON,Oak Ridge National Lahiatory, Oak Ridge, Tenn.
4 thallium-activated sodium iodide gamma-ray spectrometer has heen calibrated with respect t o gamma-ray energy and efficiency between the energies of 30 k.e.v. and 2.76 m.e.v. This calibration makes it possible t o solve many quantitative problems in analytical radiochemistry simply, quickly, and often without a n y chemical separation or chemical treatment of the sample. T h e gamma spectrometer goes beyond radiochemical analysis in t h a t a particular radioisotope rather than just t h e element is identified. Several types of problems t o which this technique has been applied were described. These include the checking of analytical methods for specificity, monitoring of O R N L radioisotope products for gamma contaminants, isotopic analysis, and identification of unknown activities in solid, liquid. and air samples. Causes for Abnormal Mass 30 Values in Nitrogen Isotope Analyses AND with the Mass Spectrometer. ROBERTL. ORY,J. M. PRESCOTT, CARLM. L Y M ~ NTexas , Agricultural Experiment Station, College Station, Tex. While conducting biological studies involving N16 as a tracer, an abnormally high mass 30 (Mao) peak was often encountered in t h e mass spectrometer curves for samples oxidized by t h e Dumas method. Of the two equations which may be used t o compute atom per cent excess N16, erratic values were obtained with t h e equation involving experimental values for M30 as well as MZ8 and M29 as compared t o t h e alternative equation which represents Maa in terms of MZB and MZS. I t appeared t h a t t h e source of t h e error might be traces of nitric oxide escaping reduction by t h e copper in the combustion tuhe. Evidence in support of this hypothesis was obtained by shaking the gas samples with alkaline potassium permanganate, which oxidizes nitric oxide. This procedure completely removed t h e abnormally high M30 peaks.
Composition of t h e Basic Ferric Formate Precipitate. Effect of Final pH. C. T. KESNER, Southern Methodist University, Dallas, Tex. T h e composition of t h e basic ferric formate precipitate varies with the final p H of t h e precipitation medium. X-ray diffraction patterns prove t h e presence of FeOOH and chemical analyses indicate a general formula of (Fe00H)z(FeOCl)~.7(FeOCHO~)~.o with I varying from 8.4 t o 15.3 a s t h e final p H is raised from 2.95 to 4.65. T h e presence of a small amount of some crystalline material which is slightly
ANALYTICAL CHEMISTRY
1934 soluble in benzene and which contains iron and chlorine is indirated by transmission of light in t h e dark field of a polarizing microscope and by qualitative tests upon beiizene extracts of t h e precipitates.
Principles of Precision Colorimetry. Two New Methods. CHARLESN. REILLY,University of North Caroline, Chapel Hill,
N.
c.
This study was made t o investigate t h e effect of t h e “dark-current” knob on spectrophotometric precision with a view toward the development of improved high-precision methods. Utilization of the knob for this purpose requires t h e use of a reference solution for setting t h e instrument zero. I n this way, apparent positive deviation from Beer’s law is achieved, with its attendant increase in preciaion. An expression for t h e relative error is derived and the conditions for its minimization were discussed under assumptions sufficiently general both t o include and extend previous techniques. Four methods are distinguished, of which two are new. One of the new methods gives t h e best precision obtainahle, using two reference solutions and other conditions selected t o make this statement true. T h e selecption procedure was described. The other new method is applicable to trace analysis, and represents the best compromise poa3ible when solutions sufficiently concentrated to permit use of optimum conditions are not available. Both methods promise substantial improvement in precision over former methods a t small extra cost in time and effort.
Effects of Time and Temperature on the Reaction of HCHO with a Modified Schiff’s Reagent. RICHARDHATFIELD A K D E . c. SMITH, Southwest Research Institute, San Antonio, Tex. T h e colorimetric test using Schiff’s reagent as modified by Denigks was studied over ? range of conditions of 0 t o 25 hours using temperatures of Z O O , 25’, and 30’ C . at varying concentrations of HCHO. A color development time of 10 minutes a t 25’ C . was establiahed as a standard for routine analysis. Experiments with both basic fuchsin and rosaniline hydrochloride showed t h a t the form of the fuchsin dye produced differences in color intensities, and Coleman and Bell’s rosaniline hydrochloride was selected as a standard. When the dichromate ion was present in concentrations less than 100 p.p.ni. it was found that a change of wave length from t h e Jtandard value of 580 t o a value of 650 m p would give results in which all values were within 10% of the niean. Experimental work also showed that HCHOderived acetals could be completely hydrolyzed when I nil. of sulfuric arid was added t o 5 ml. of t h e acetal solution and allowed to stand 15 minutes a t approximately 65’ C . T h e resulting H C H O could then be determined by t h e modified Schiff’s test. d qualitative test wap developed t o determine whether an acetal is derived from H C H O or a higher aldehyde by hydrolyzing the acetal solution and then preforming the modified Schiff’s reagent to see if H C H O is present.
Colorimetric Determination of Small Amounts of Uranium in the Presence of Bismuth. Pentaether Thiocyanate Method. LAVAD.A MOUDYA N D LOUISS I L Y E B M W North , .Imerican Aviation, In[.., Downey, Calif. Bismuth, in microgram quantities, interferes in t h e colorimetric determination of uranium by t h e better known reagents such as thiocyanate and 8-quinolinol. T h e usual chemical procedures for the preliminary separation of bismuth from uranium are ineffective. as small portions of uranium accompany t h e bismuth. This has been noted for cupferron. T h e preliminary bismuth oxychloride separation or t h e electrodeposition of bismuth leaves residuals of bismuth (micrograms) which tend toward high uranium results. It was shown t h a t t h e residual bismuth in t h e uranium solution may be extracted with dithizone, and t h e uranium determined photometrically as thiocyanate, in t h e 350 to 400 m+ range.
T h e visual end point of t h e Liebig-DenigBs titration method for total cyanide is useful for concentrations down t o about 20 p.p.m., but is not rerommended for routine application when lower concentrations are to he encountered.
Determination of Free Gossypol in Mixed Feeds. R . W. STORK. T. HOLLEY,Georgia Agricultural Experiment Station, Experiment, G a
HERR ASD
Common methods for the deterrnination of free gossypol are inapplicable t o mixed feeds because of various interfering substances. A study of other reagents and solvent systems showed t h a t phloroglucinol is a satisfactory reagent and 2-butanone azeotrope a suitable extracting solution. Gossypol-time extraction curves of raw, hydraulic, screw-pressed, and solvent-extract,ed meals show a plateau after a n initial rapid extraction rate. T h e values at a point just past the sharp break are in close agreement with those by t h e panisidine method. These values are defined as free gossypol. The color developed a t room temperature by phloroglucinolgossypol in the presence of strong acid is estimated spectrophotometrically a t 550 mp. A small amount of aniline in t h e extracting solution checks the reaction of gossypol with substances in other components of t h e feedstuffs. Theoretical Yalues are obtained for meals mixed with alfalfa, minerals, ground rorn. barley, oats, wheat, and blackstrap molasses, either indiridually or in various formulations. As low as 0.004% free gossypol in mixed feeda is readily determined.
Photometric Titrations in Nonaqueous Solvents. CHARLESN. REILLEYAND B ~ R B A SCHWEIZER, R.~ University of North Caroliua, Chapel Hill. ?;. C . Photometric titrations have proved valuable ill circumventing difficulties and inadequacies experienced with other end-point detection techniques. For this reason a study of the application of t h e photometric method in t h e general field of acid-base titrations in nonaqueous media seemed desirable. Glacial acetic acid was einployed as the solvent and a glacial acetic? acid solution of perchloric acid was used t o titrate several weak bases. T h e titration cell was placed directly in the light path of a Bcckman DU spectrophotometer and the absorbancy a t a n experimentally determined wave length was plotted against the corrected volume of the titrant.. I n this manner hases such as o-chloroaniline, m-chloroaniline, and quinoline gave distinct breaks a t the equivalent point (agreeing well with potentiometric end points) and were therefore successfully titrated. T h e possibility of titrating substances was attempted for cases where neither acid nor base forms show absorbancy in the ultraviolet region. Thib was accomplished by addition of an absorbing species of weaker bassivity. Successive end-point breaks indicate the volume equivalent to the quantity of earh component.
Spectrophotometric Determination of Copper after Solvent Extraction of the Copper-Pyridine-Thiocyanate. STEPHENS.BarRD, Naval University of Texas, .lustin, Tex., .IND D.AVIDIT.SANSHUCK, Powder Factory.
In the determination of less t h a n 0.2% copper in aluminum, t h e electrolytic method was found to give erratic results. T h e usual colorimetric copper determination using sodium diethyl dithiocarbamate required a preliminary separation, thereby making the determination time-consuming. A solvent extraction method was sought, as it was felt t h a t a simultaneous separation and determination could be accomplished by choice of the proper reaction. T h e method chosen for study is t h e reaction between copper, thiocyanate, and pyridine t o yield t h e insoluble compound C U ( C B H ~ N ) ~ ( C N S ) Z . T h e dependence of various solution factors and foreign ions upon the absorbance of t h e solution was shown, as well as t h e effect of variou? solvents used t o extract t h e colored compound.
Determination of Low Hydrocyanic Acid in Acrylonitrile. ROBERT L. MACTEASD M. L. OWENS,JR.,Monsanto Chemical Co., Texas City, Tex. T h e need for a precise but simple method for the determination of free and combined hydrocyanic acid in the range of 0 to 100 p.p.m. in acrylonitrile led t o a study of four different methods. I t has been found t h a t simple potentiometric procedures give sufficient precision and accuracy for t h e determination of either free hydrocyanic acid or total (free and combined) hydrocyanic acid on routine samples. Where a higher precision is required, a simplification of t h e phenolphthalein colorimetric procedure has been found more satisfactory.
Influence of Perrhenate Ion on Flame Photometric Determination of Potassium. A. D. MELAVEN A N D 1.J. CHIDWELL,University of Tennessee, Knoxville, Tenn. Rhenium in t h e form of t h e perrhenate ion, ReOd-, will cause low results in t h e flame photometric determination of potassium using both the direct intensity and t h e internal standards methods. A Model 52-C Perkin-Elmer flame photometer was used in t h e work, covering t h e range 0 t o 100 p.p.m, of potas&mi and 0 to 5000 p.p m. of rhenium as perrhenate ion.
V O L U M E 2 5 , NO. 1 2 , D E C E M B E R 1 9 5 3 The internal standard method is subject t o less error than t h e direct intensity method. I n addition t o t h e error due t o perrhenate ion, hydrogen ion also depresses t h e direct intensity readings but not those by t h e internal standard method. I n t h e use of either method, t h e greatest relative error was found with t h e smaller potassium concentrations. I n the case of t h e internal standard method, an aliiiost linear relationship exists between instrument reading and c~oi~centration of rhenium present for a given concentration of potasziutn. I n both met,hods. a given ratio of rhenium t o potassium by weight caubes a constant relative error over t h e concentration range used. This relationship w a s first noticed in t h e case of pure potassium perrhriiate and was found to he true for other ratios.
Flame Photometric Determination of Calcium and Magnesium. FLORENCE B. RTROHIIEYER. BYRONE. LEACH,ASD ROBERTG . H E A T HTulane , L-niverdy, STewOrleans, La. The determination of t.alciuni and magnesium by flame photometry was undertaken in order to study t h e variations encountered in biological specimens:. T h e iii..trument used was a Beckman DU spectrophotometer with flanie attachment and a photomultiplier. -1 number of conflicting s u h t a n r e ~are present in these materials and must be taken into 1-onsiderarion. h series of studies was carried out on t h e efrects of sodiiiiii. potassium, and phosphate and t h e mutual effect of calriuni and niagiieaium on each other. T h e wave length uacd for calvium w a s 554 niw and 371 m+ for magnesium. T h e literature reported that 40% isopropyl alcohol enhanced calcium, so this wa-. the first effect studied. I t was also found t h a t t h e isopropyl wa' n e i ' e s a r y for t h e magnesium determination. .Is a result. of all these effecta a diluting fluid containing sodium, potassium, and phosphate was used and made u p t o contain 40% isopropyl alcohol. It was found t h a t calcium has no appreciable effect 011 magnesium but that magnesium has a depressing effect on call ium, T o a series of solutions containing a known quantity of calc*iuni.varying quantities up t o equivalent amounts of magnesium were added. T h e most feasible concentration appears t o be a close approximation to t h a t found in biological fluids.
Effects of Certain Alkali Compounds in the Burning of Powdered Graphite Samples. E. L. GROVEAND J. A. XORRIS,Oak Ridge National Laboratory, Oak Ridge, Tenn. Effects of fluoride, chloride, carbonate, and sulfate compounds of lithium, sodium, and potassium were studied in t h e burning of powdered graphite staiidards containing oxides of silicon, aluminum, iron, and carbonates of barium and calcium. T h e procedure consisted of burning a 1-mg. graphite-oxide standard mixed with 9 mg. oi various ratios of the compound and graphite powder. Centerdrilled 3 / ~ ~ - i n cdiameter h lower electrodes with very thin walls were used and the sampler: burned to completion in a &ere, 2400volt a.c. arc. Moving plate studies of t h e various standard elements in the mixtures gave information on t h e smoothness of burning, time required, and completeness of burning. Potassium and sodium fluoride g a m cleaner and sharper burn-out of the elements silicon, iron, and aluminum t h a n did t h e same weight of the other compound?.. Fluorides of lithium, sodium, and potassium produced spectrograms with less background t h a n t h e other salts. Also, t h e lithium fluoride and sodium fluoride enhanced t h e a r c lines more and suppressed t h e spark lines more than the other compounds. Ratios of 1 p u t >alt to 7 parts graphite did not produce effective C S band s u p p r e ~ ~ i o i2ion.ever. i: a ratio of about 2 to 5 yielded good rehults. Lithium fluoride appears to be t h e most effective. T h e use of equivalent weights of lithium for t h e different salts did not produce eclrial suppression effertc.
Polarographic Determination of Vanadium and Molybdenum in the Presence of Ethylenediaminetetraacetic Acid. R O B E R TD. FELTH A M AND ERNEST L. MARTIX, University of New Mexico, Alhuquerque, X. M. T h e use of salts of ethylenediaminetetraacetic acid (Versene) as the supporting electrolyte and complexing agent in t h e determination of vanadium(V) and molybdenum(V1) mms described. T h e half-wave potentials of vanadium(V1 Versenate and molybdenum have been reported, h u t no suitable method for their determination in t h e same solution has been found in the literature. T h e concentration of the vanadium Versene complex is proportional t o t h e diffusion current u p t o a concentration of 1.3 X 10-3 formal, when measured a t -1.560 volt vs. t h e S.C.E., and a p H of 10.0. Results of t h e measurements of vanadium in the presence of molybdenum and tungsten were given. Molybdenum gives a douhle
wave in acid solution a t a p H 2.8. T h e half-wave potentials a r e -0.244 and -0.608 volt 21s. the S.C.E. T h e heights of the waves are proportional t o t h e molybdenum concentration u p t o a concentration of 1.1 X 10-3 formal, when measured at -0.460 or -0.850 volt vs. t h e S.C.E. Analyses of various test solutions containing vanadium, molybdenum, and tungsten were reported.
High-Frequency Measurements as Applied to Titrimetry. H. W . HAMME,E. L. GROVE,AND J . L. K-ASSNER, University of Alabama. University, >Ua. T h e high-frequency conductance and ausceptance were measured for certain coil-type containers used in "high-frequency technique*" over a range of frequencies. At a certain narrow frequency band, or bands depending on t h e coil, there appears a sharp maxiniuni. or maxima, of conductance accompanied by a sudden drop, then rise of t h e susceptance values. If pure water is added to t h e container (which represents an increase in t h e over-all capacitance of the coil) the conductance and capacitance maxima shift to a lower frequency. If the distilled water is replaced with a dilute electrolyte t h e peak, o r peaks. is ahifted t o a still lower frequency. This narrow band reprehents a region of high sensitivity and appears to be a function of t h e type and size of the coil. t h e solvent and its concentration, and the distributive rapacity between the coil and its ewe. Different electrolytes caused the high-frequency conductance n ~ a x i m u mto shift different amounts. Thus, t h e shape of various titration curves can be predicted, depending 011 whether t h e highfrequency conductance drops or rises t o the salt value and then rises or drop. as ail increasing amount of the tirraiit is added.
Preliminary Studies of the Separation and Determination of Bismuth, Antimony, and Tin by Controlled Cathode Electroanalysis. JOHN A. DE.W ~ N S. D A. REYNOLDS, University of Tennessee, Knoxville, Tenn., and Oak Ridge Kational Laboratory, Oak Ridge, Teiin. A preliminary study has heen made of the separation and determination of bismuth, antimony, and tin by electrochemical means. using coiitrolled cathode potential. The effects o l electrolyte coinposition, cathode potential, and temperature were reported, with respect t o separations of t h e three metals and the degree of recovery of each. T h e use of radioactive trarers in tehting separations was described. Rest results were obtained by use of an electrolyte containing sulfate and citrate with hydrazine as depolarizer. .I procedure was reported which will serve for approximate determination of bismuth. aiitimony, and tin in alloys and other mixture>.
Peak Volume-Concentration Concept in Organic Acid Chromatography Using Progressively Changing Solvents. CHARLESMADER, Oklahoma A . & M. College, Stillwater, Okla.
.I general volume-concentration equation was derived and proved experimentally. T h e peak volume-conce~itr:~tioi~s of the acids were found to be described by characteristic equations. T h e w e of t.he iriterrelatioir of the peak volume-concentrations of the acidh and t h e fiictors influenc.iiig t h e choice of a sghtem for separating a particular group of acids was shown to have theoretical babii. Chromatographic Fractionation of Wood Carbohydrates. ROBERT R O YBRIDGEShlasonite Corp.. Laurel. Rlis>.. The complex mixture of water-soluble carbohydrates, conimercially known as Masonoid, resulting from t h e hydrolytic degradation of wood hemicelluloses in t h e production of fiber by the Masonite process has been partially resolved into 20 individual simple sugars and oligosaccharides by t h e application of a combination of t h e charcoal column chromatography of Whistler and Durso and large sheet paper chromatography. Ten of t h e compounds are known and have beeii identified by paper chromatographic comparison of t h e original or its hydrolysis products or by physical constants. T h e remainiug ten compounds are not definitely identified except with respect t o their size and t,he simple sugar units of which they are composed, both of which are obtained from paper chromatographic evidence. The .-imple sugars isolated are xylose, arabinose, glucose, galactose, and manno6e and the oligosaccharides are made up of units of these sugars (except arabinose) arranged either in polymers of different sugar units or t h e same sugar units ranging in size from two to six units. Oligosaccharides larger t h a n six units are not readily separated by rharcoal column chromatography or resolved by paper chromatography. That portion of Masonoid t h a t is unresolved is in this rla3sificat loll.
1936
ANALYTICAL CHEMISTRY
Analysis by Alumina Adsorption of the Aromatics Boiling Above F. i n Jet Fuels. C. M. MCKINNEYAND R. L. HOPKINS,U. S. Bureau of Mines, Bartlesville, Okla. 400'
T o provide information regarding t h e composition of fuels in t h e jet-engine fuel (JP-4) boiling range, partial analysis b y alumina adsorption was attempted of t h e material boiling above 400' F. Fuels from 11 crude oils from California, Illinois, Nebraska, Oklahoma, and Texas were prepared and analyzed. T h e crude oils were selected t o provide fuels with considerable variation in composition. T h e aromatic portion of each fuel was separated from t h e paraffinnaphthene portion using a' conventional silica gel adsorption technique. A high-dilution alumina adsorption technique using selective desorption for separation of the aroniatic portion into fractions was described. Tables of density and refractive index data compiled from various literature sources for compounds in t,he boiling range studied were given for comparison with similar data determined on each of the aromatic fractions from which adsorptogranis were plotted t o illustrate the degree of separation obtained. Smoke point determinations were made on t h e original fuels, the original fuels less t,he aromatics boiling above 400° F., and the original fuels less the polycyclic aromatics boiling above 400' F. Spectroisotopy. Applications of High Resolution Spectroscopy. J. RAND MCNALLY, JR., Oak Ridge National Laboratory, Oak Ridge,
from chemically nonequivalent protons or fluorine nuclei in liquid samples, using an extremely homogeneous polarizing magnetic field and slow scanning. Typical results were displayed and discussed in terms of present theories of molecular structure. Applications of Ultraviolet Spectroscopy. NORMAND. COGGEGulf Research & Development Co., Pittsburgh, P a .
SH.
