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A complete account of t h e present status of variance components as a n added tool in design and interpretation of experiments is given, along with several key-out tables for t h e more Anal se des vins. P. Jaulmes. 574 pages. Poulain, Editeur, 5 &and’Rue, Montpellier, France. Fr. 2.200. common designs. Neuere massanalytische Methoden. E. Brennecke, K . Fajans, It is not obvious t o this reviewer that t h e book adds anything N . H . Furman, R. Lang, and H. Stamm. xx f 347 pages, to a n already crowded field, other than examples of the industrial Ferdinand Enke veriag, Hasenbergsteige 3, Stuttgart-W, ROBERT J. MO~YROE Germany. Geheftet DM 46. Gansleinen DM 49. application of statistical methods.
New York Meeting-in-Miniature HE New York Section of the AMERICANCHEMICAL SOCIETY Theld a meeting-in-miniahre in New York on February 8, at which papers on analytical, biochemistry, physical and inorganic, polymer, and organic chemistry were presented. Abstracts of the papers of the Analytical Chemistry sessions are printed here. Further information should be obtained directly from authors. Origin of Some-Methods of Quantitative Organic Analysis Via Functional Groups. MORITZKOHN,Benzol Products Co., Newark, N. J. I n the course of time the quantitative analysis via functional groups became an indispensable part of organic elementary analysis. The origin of the methods for the determination of methoxyl (alkoxyl) (5. Zeisel, 1885-1886), methylimide (alkalimide) (J. Herzig and H. Meyer, 1894-1897), and the iodine number of unsaturated compounds (iodine number of fats) (A. V. Huebl, 1884) is explained. Zeisel’s original method enabled Zeisel and Fanto to work out a precise determination of glycerol (1901-1902), later modified by Willsttitter and Madinaveitia (1912). The introduction of Pregl’s methods for micro organic analysis led him, his coworkers, and other chemists to introduce micromethods for organic analysis via functional groups. This development increased the international use of these methods. Application of Ion Exchange Techniques in the Spectrophotometric Determination of Codeine and Prophenpyridamine in a Sirup. E. R. Sguibb & Sons, Brooklyn, MARIEJONES AND R. L. THATCHER, N. Y. Codeine phosphate and prophenpyridamine maleate, l-phenyl-l(2-pyridyl)-3-dimethylaminopropanemaleate, in a sirup were determined without separation on the basis of their ultraviolet absorption by the multicomponent method. Separation from other absorbing entities such as sulfonic acid dyes and sodium benzoate was accomplished by passing the sirup through a column of a strongly basic synthetic resin. The interfering anions were absorbed on the resin and the alkaloidal salts were converted to the bases by this procedure, and collected in the eluate. Absorbancy was then determined on the eluted solution at the maximum wave length of each component, and potency, calculated by the use of simultaneous equations. The solvent used was 70% alcohol, which was found adequate for complete solubility of the alkaloidal salts and bases, and contained sufficient water for the functioning of the ion exchange mechanism. Recovery was about 95 to 96% for codeine and 98% for prophenpyridamine Chemical Analysis for Vitamin Bn. G . 0. RUDKIN, JR.,AND R. J. TAYLOR, Chm. Pfizer & Co., Brooklyn, N. Y. A chemical method of analysis for vitamin BLZhas been devised which is based on the difference between the spectrum of vitamin Blt activity is extracted in the form of its dicyanide complex. This highly selective extraction achieves an eightfold concentration and eliminates the major portion of interfering pigments generally found in fermentation broths. Results indicate that the method is considerably more reliable than the biological assay. Ultraviolet Spectra and Tautomeric Equilibria of Mercapto and Thioxo Acids. J. J. DR~NEYA N D M. CEFOLA,Fordham University, New York, N. Y. Little is known about the metal complexes of mercapto acids, but from the information available (most of which relates to the complexes of thioglycolic acid and cysteine) it can be inferred that the mercapto acid complexes are in many cases substantially different in their structure and properties from their hydroxy acid analogs. Furthermore, the mercapto acid complexes often possess properties that lend themselves to the determination of the metals involved. Beforeclarifying the nature of these complexes, certain fundamental data regarding the mercapto acids themselves were necessary.
The ultraviolet spectra of a number of new and previously synthesized mercapto acids have been taken in absolute alcohol. In this region there are usually one or two absorption maxima. The different maxima are assigned to respective “chromophoric” groups. There is evidence that thioxo acids can exist in tautomeric equilibria with a thio enol form. Results obtained from the iodine titration of the thio enol form and the absorption spectra were discussed. The per cent thio enol present in different solvents was also studied. Benzoylthiopyruvic acid has been synthesized, and its ultraviolet and infrared spectra taken. The potentialities of this compound as a reagent were discussed. Field Estimation of Sulfites in Waters. SIDNEYSESSMANAND IRVING L. PORTNOY, Water Service Laboratories,Inc., New York, N. Y. Sulfites in boiler waters are usually determined by addition of an excess of iodine folloned by titration with thiosulfate. In large steam generating plants equipped with sample coolers and full-time operating personnel, this procedure is satisfactory, but many smaller boiler plants find it too cumbersome. A method was developed in which a boiler water sample is added directly to a measured volume of an acidified chromate solution. Sulfites react with the chromate, reducing it to the chromic ion, which is substantially colorless in the concentrations used. The residual chromate color indicates the sulfite content of the boiler water. An additional advantage lies in the fact that the sample used in the field test can be brought back to the laboratory for more exact check with a colorimeter. Determination of Zinc in the Presence of Copper in Water. LEOI. PINCCS,Kater Service Laboratories, Inc., New York, N. Y. A method was described for determining up to 10 p.p.m. of zinc in the presence of as much as 10 p.p.m. of copper in potable and process waters. Sodium diethyl dithiocarbamate is used t o produce a turbidity which can be quantitatively measured with a photoelectric colorimeter. The test is unique in that sodium diethyl dithiocarbamate is also used to separate the copper from the zinc. This separation is simpler and less time-consuming than the present A.Ph.A. method and other common methods. Copper is separated by precipitation nith sodium diethyl dithiocarbamate in a mildly acid solution and is completely removed by filtration. Under these conditions zinc remains in solution as a complex salt. The soluble complex, excess carbamate reagent, and acidity are destroyed by oxidation and evaporation to dryness. The zinc residue is redissolved in distilled water and determined turbidimetrically by addition of fresh sodium diethyl dithiocarbamate to the nearly neutral solution. Determination of Heavy Metals and Silica in Chromate-Treated Cooling Waters. SIDNEYSUSSMAN AND IRVING L. PORTNOY, Water Service Laboratories, Inc., New York, N. Y. Because of their color and chemical reactivity, the chromates interfere with the determination of heavy metals and silica in cooling water treated for corrosion control. Ion exchange procedures can be used to separate the chromate from these ions before determination by standard methods or slight modifications of these. Heavy metals are separated by passing the treated water through a column of acid-regenerated cation exchanger. The heavy metals are retained in the column, from which they may be recovered by elution with acid. Traces of organic matter and of the eluting agent sometimes interfere with the standard determinations. This interference can be readily eliminated by simple procedures. For the separation of silica from chromate, the sample is passed through a column of the chloride salt of a weakly basic anion exchanger. The chromate is retained in the column, liberating an equivalent amount of chloride. The silica passes through and may be determined in the column effluent by the standard colorimetric procedures.
V O L U M E 2 4 , NO. 3, M A R C H 1 9 5 2 Determination of Boron in Ferroalloys. HERMAN BLUYENTHIL, American Electro Metal Corp., Yonkers, N. Y. Boron as an alloying element in steel is able to substitute partly for manganese, chromium, molybdenum, and nickel, giving the same hardenability effect as these scarce and strategic metals. The actual amount of boron necessary to give the optimum effect seems not to be critical, as long as the boron content is in the range of from 0.003 to 0.0008%. A fast and accurate procedure for the determination of boron in the addition agent is therefore more important for the steel manufacturer than the finished steel. Boron in alloys is generally determined by distilling it off as methylborate. Other methods carry out the separation of boron by precipitating the metals with sodium carbonate, sodium hydroxide, calcium carbonate, or barium hydroxide. These methods are applied by their authors only for one or a very limited number of compounds. The method discussed claims a more general applicability. I n this method the sample is brought into solution either by boiling with acids or by fusion n,ith sodium carbonate and decomposing the melt with hydrochloric acid. The metals are precipitated with barium carbonate. If manganese is present, barium hydroxide must be added t o complete precipitation. If manganese and aluminum are present, two precipitations are necessary, the first with barium carbonate to precipitate all metals but manganese, and the second to precipitate manganese. Boric acid in solution is then titrated in the usual manner, either potentiometrically or visually. All commercially available boron addition agents have been analyzed in this way. Colorimetric Method for Determination of Catalase Activity. GERALD B. DOBKIK, Queens General Hospital and Brooklyn College, Brooklyn, N. Y. A colorimetric method for determining catalase activity has been worked out in order to study the enzyme action in various biological fluids. Properly diluted catalase is allowed to react with a solution of hydrogen peroxide, buffered a t the pH of optimum enzyme activity. At intervals, aliquots of the mixture are withdrawn and reacted with alkaline ferricyanide in the ice bath. This is based upon the fact that, in alkaline solution, peroxide acta as a reducing agent, converting ferricyanide to ferrocyanide. The ferrocyanide is then reacted with a gum ghatti solution containiiig ferric ions. This ferriferro system forms Prussian blue, the intensity of which is a measure of the undecomposed hydrogen peroxide, which, in turn, is a measure of catalase activity. The activity of human serum catalase is being studied employing the above-mentioned method. Work is in progress t o establish normal values for serum and plasma catalase activity, and to relate significant changes in the enzyme activity, to pathological changes. Kinetic studies will be performed to clarify the order of reaction. Measurement of Radioactive Hydrogen by Solid Counting. W4xL. EIDINOFF AND JOSEPHE. KNOLL, Sloan-Kettering Institute, Queens College, Brooklyn, ?T. Y.
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The absorption of beta particles from radioactive hydrogen by thin aluminum and gold foils was measured up to absorber thicknesses of 1 mg. per sq. cm. in a windowless counter. Absorber thicknesses of 0.035, 0.12, 0.28, and 0.51 mg. per sq. cm. reduce the counting rate in the absence of ab2orber by the factors 0.5, 0.1, 0.01, and 0.001, respectively. Up to 0.15 mg. per sq.cm. the counting rates may be represented by the equation: 1/10 = e-18.7T where I and I o are the measured counting rates at absorber thicknesses of T and 0 mg. per sq. cm., respectively. This equation leads to the self-absorption correction factor to infinitely thin sample counting of 1 - e-18.7T
18.7T applicable to sample thicknesses up to 0.15 mg. per sq. cm. The observed counting rate at an aluminum absorber thickness of 0.6 mg. per. sq. cm. is a measure of the Bremsstrahlung radiation and accounts for 0.05% of the counting rate for zero absorber. Determination with Use of P3*of Quantity of Oral Secretion Deposited in Host Tissue by Lygus oblineatus. FLORENCE FLEMION, P. MILLER,. ~ N DR I C H ~ R hf. D WEED,Boyce Thompson LAWRENCE Institute for Plant Research, Inc., Yonkers, N. Y. L y g u s oblineatus is destructive to many crops and is responsible for large economic losses. Because the injury to plant tissue following feeding seems to be greater than would be expected from the withdrawal of cell fluids only, it has been suspected that toxic salivary secretions are involved. By allowing insects to feed on sucrose solutions to which radioactive phosphate had been added in sufficient quantity to gire several hundred thousand counts per minute for each insect (under conditions in which about 20% of the disintegrations were counted) significant counts were obtained in the saliva. With
595 the aid of a micropipet it was possihle to determine the radioactivity of the saliva per unit volume and thus relate activity imparted on feeding to the volume of saliva injected. I t was found that the insects deposit between 1/30 and 1/20 microliter of saliva when feeding. The saliva is slightly alkaline in reaction and gives observable injurious effects when injected directly into plant tissue without insect feeding. Recent Trends in Solvent Extraction. GEORGEH. MORRISON, Sylvania Electric Products Co., Flushing, L. I., N. Y. Analytical liquid-liquid extractions fall largely into three classes: inorganic, organometallic, and organic. Some of the more recent developments in this field of chemical separation were discussed, including the action of combinations of salting-out agents, the use of radioisotopes in solvent extraction, continuous extraction using chelates, and countercurrent distribution. Quinaldine Red Method of Phosphate Determination. BASILC. SOYENKOFF, New York University College of Dentistry, New York, N. Y. The method is mainly intended for protein-free filtrates and digests of biological materials. The original method [ J . Biol. Chem., 168, 447-57 (1947)l was based on a highly sensitive color reaction (extinction coefficient = 2 . 2 per p.p.m. of phosphorus). I n the improved method, a readily soluble dye has been substituted for quinaldine red. The effects of pH and interfering substances are reduced, thus permitting gains in accuracy and speed. Readings can be made over the 0.02 to 0.2 p.p.m. of phosphorus range with 1% precision, using the Klett colorimeter and tubes. Extraction of Iron and Nickel with Thenoyltrifluoracctone. BRUNO MICCIOLIAND MICHAELCEFOL.~, Fordham University, Ken, York, N. Y. Beta-diketones hare been extensively studied as chelating agents for metal ions. In particular, numerous investigations have already been described in which thenoyltrifluoroacetone, more commonly known as TTA, has been used as a complexing agent for the isolation and the purification of many of the radioactive isotopes. The work reported was undertaken t o study the formation and the extraction in benzene of the iron and nickel complex as a function of pH, using the stable form of these elements, in order to determine the possibilities for analytical separations. Data relating amounts extracted versus time and distribution ratios have been obtained for iron and nickel. From this the equilibrium constants for the formation of the iron complex have been calculated for two different concentrations of the organic reagent. Kickel does not extract under the same conditions, possibly because of the formation of an insoluble double salt. Microdetection of Sugars by Means of Tetrazolium Salts. KICHOD. CHERONIS, MILTONCOOPER, .tsD ALFRED GROSSO, Brooklyn College, Brooklyn, N. Y. The use of 2,3,5-triphenyltetrazoIium chloride, 2-methyl-3,5diphenyltetrazolium chloride, and other tetrazolium salts for the identification of functional groups with reducing properties could be expected by the ease nith which these tetrazolium salts are reduced by enzyme systems. Though the reduction of tetrazolium salts by sugars has been reported previously, the reaction has not been adapted to the detection of reducing functional groups because at alkaline pH the tetrazolium salts develop similar color as in reduction. The paper reported a study of the threshold of stability of tetrazolium salts a t alkaline pH. I t has been shown that the stability is a function not only of pH but also of the concentration of the quaternary salt. A simple test utilizing 1 mg. per ml. of tetrazolium chloride at pH 11.9 to 12.0 and 100’ C. is capable of showing color development with reducing sugars. The following compounds were tested with tetrazolium and Tyith Fehling’s and Benedict’s solutions: arabinose, xylose, fucose, lyxose, rhamnose, levulose, glucose, mannose, galactose, lactose, sucrose, maltose. cellobiose, melibiose, trehalose, raffinose, and amygdalin. It is possible to detect 2 to 5 micrograms per milliliter of all reducing sugars by means of the tetrazoliom ted. LAS
Titration of Polyampholytes. S. H. PINSER AND C. F. HISKEY, Polytechnic Institute of Brooklyn, Brooklyn, N. Y. Polyampholytes prepared by copolymerization of dialkylaminoethyl acrylates and methacrylates with methacrylic acid, acrylic acid, and itaconic acid have been titrated with hydrochloric acid and with sodium hydroxide, using a semimicro electrometric method. The maximum acid and base-binding capacity of the polyampholytes was found to agree with the content of tertiary amino groups and carboxylic acid groups as found by analysis of nitrogen content. In addition, the isoelectric points of the polyampholytes and the apparent pK’s of the acid and basic groups of the polyampholytes could be obtained from the titration curves.
Pittsburgh Conference on Analytical Chemistry HE Pittsburgh Conference on Analytical Chemistry and TApplied Spectroscopy was held in Pittsburgh, Pa., March 5 to 7 , 1952, under the auspices of the Analytical Chemistry Group, SOCIETY,and t h e Pittsburgh Section, AMERICANCHEMICAL Spectroscopy Society of Pittsburgh. Abstracts of the papers presented are printed below. For details regarding publication of the papers, the individual authors should be consulted.
The fact that the electrode material affects the course of an electrolytic reaction is not new, but the present study lends further support to the possibility of surveying quickly by polarography the gross effects of electrode materials on electro-organic syntheses. It also demonstrates that caution must be exercised in reporting formal redox potentials which are determined polarographically.
Pittsburgh Analytical Chemists Serve the World. J. C. WARNER, President, Carnegie Institute of Technology, Pittsburgh, Pa. In his keynote address, Warner welcomed the conferees to Pittsburgh and presented a picture of the contributions of Pittsburgh analysts, both chemical and spectroscopic, to the world of science and industry. As president of an outstanding Pittsburgh institution, the Carnegie Institute of Technology, as a chemist of long and eminent standing, and as a leader in the ACS and other technical societies, Warner can view the analytical scene with clarity and perspective. Pellet Method Using Silver Powder for Spectrochemical Analysis of Low-Alloy Steel. ERNESTH. S. VAN SOMEREN, editor, Spectrochimica A c h , Broxburne, Herts, England. The uncontrolled spark normally used for the spectrochemical analysis of low-alloy steels is adequate for manganese and the added elements, but not for Si, Cr, Mo, Ni, V, and A1 when they occur in traces below about 0.1%. By using the d.c. or a.c. arc the lower limits for traces can be reduced about tenfold, but quantitative precision is unsatisfactory because of the effect of some elements on the spectra of others, and of sample size on the spectrum. In order to avoid these two sources of error, a molded pellet is made of equal weights of sample in the form of filings and silver in the form of a pure precipitated powder. These pellets are fitted into a closely fitting socket in the top of a copper block, and a silver wire counterelectrode is used held in a copper clamp; each electrode is held in a mass large enough to dissipate most of the heat from the arc. An a.c. arc is used to avoid the fact that different elements are more easily detected in different poles of the d.c. arc. Uniformity of the arc is promoted by a needle point to aid ionization of the gap; and the arc brightness is monitored by a photocell rather than by adjusting a resistance to constant current. The weight of the filings and of the pellets is controlled with a torsion balance. For the elements such as aluminum and silicon, where trace analysis by chemical means is difficult, synthetic standards have been made by mixing steel filings of known composition with pure iron powder. Electrolytic iron is not so good as carbonyl iron powder for this purpose. The lines selected for Mn, Si, Cr, Ni, Mo, V, AI, and Sn in steel were tabulated, and the precision attained in several years’ work was reported. This is not on the whole so good as the precision of spark testing of samples of uniform type; reasons for the lower precision were correlated with the type of source used and the choice of lines available.
High Frequency Measurements in Chemical Analysis. PHILIP J. ELYINQ,Pennsylvania State College, State College, Pa. (now at Harvard University, Cambridge, Mass.). The investigation of high frequency methods for use in analytical chemistry has become increasingly important during the past few years. Much of the work has been centered on the construction of suitable oscillators which have the necessary stability and sensitivity for accurate concentration measurement. As far as the chemical application of the oscillators is concerned, the emphasis thus far has been mainly on the study of inorganic reactions. In particular, titrations have been studied which exhibit inflection points such as acid-base neutralizations and precipitation reactions. A relatively small amount of attention has been directed toward the use of high frequency methods in the study of organic systems, although the possibilities here should be obvious. For example, any organic or inorganic reaction which involves a change in the electric properties of the solution as a function of time may be conveniently studied. The only essential criterion is that the change in the electrical properties be an accurate indication of the corresponding change in the electrical properties be an accurate indication of the corresponding change in concentration of the solution. A linear relationship between the electrical property and the concentration would naturally be preferable for a simple interpretation of the results. This is not usually the case; nevertheless, if the relationship is known with a fair degree of certainty, the interpretation may still be made without excessive difficulty. The exact nature of the properties measured in the field of a high frequency oscillator is not clear. Among others, the property could be conductance, capacitance, or merely power absorption. In many cases, the measurement undoubtedly involves a composite of these quantities. The predominating factor will depend on the material being studied, the conditions of the experiment, and the design of the high frequency instrument itself. The potentialities of the use of high frequency oscillators are numerous. Because any system can be studied in which a change in concentration is accompanied by a change in electrical properties, the method lends itself to the study of reaction rates and mechanisms, the identification of compounds, and the usual systems encountered in titrimetry. Polarographic Determination of Lead in Beryllium. RALPHW. BANE,Chemistry Division, Argonne National Laboratory, Chicago, Ill.
A rapid polarographic method for the determination of small amounts of lead in beryllium metal was described. No separations are necessary. An acid solution of 2 M beryllium chloride acts as the supporting electrolyte. The concentration of lead is read from a calibration curve prepared with known amounts of lead under the same conditions as in the analysis. In the range of 200 t o 800 p.p.m. of lead, the precision is 10% or higher.
A. IRWIN, MediRole of Analyst in Industrial Hygiene. DUDLEY cal Director, Aluminum c o . of America, Pittsburgh, Pa. From his wide experience in the field of industrial medicine and hygiene, Irwin discussed the contributions of analytical people to this field. Examples in which chemists, spectroscopists, and x-ray workers have provided analytical information leading to the solution of medical problems were cited and the role of the analyst, past, present, and future, in the field of industrial hygiene was discussed.
Application of Polarographic Methods to Analysis of Materials Encountered in Zinc Smelting Operations. PHOEBE RUTHERFORD, A. MEREDITH,St. Joseph Lead Co. of LOUISA. C H ~A,N D JACK Pennsylvania, Monaca, Pa. Polarographic methods for the analysis of materials such as concentrates, intermediate substances, and finished plant products were described. The apparatus used was presented first. Then were discussed: methods of standardization based on the relation of diffusion currents of Cu, Cd, and Zn to that of Pb; the effect of zinc concentration, a viscosity effect, on the diffusion currents; the interference of some metal ions and their elimination, and the concentration ranges covered and data illustrative of accuracy obtainable.
Polarographic Studies with Solid Electrodes. L. B. ROGERS AXD SAMUEL S.LORD,JR., Laboratory for Nuclear Science and Engineering and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Mass. Although data obtained with solid electrodes are usually not reproducible as those obtained with a dropping mercury electrode, solid electrodes of noble elements can be used to study reactions occurring at potentials where a mercury electrode would dissolve. In the past, it has been conventional to use platinum as the solid electrode, but studies have been carried out in which the polarographic behavior of simple inorganic and organic reactions at platinum, gold, and graphite electrodes both stationary and rotating were compared. It was found that the reproducibility of the diffusion current as well as the value for the half-wave potential was sometimes affected by the electrode material. Furthermore, the use of a stationary electrode often produced better polarographic results for a given reaction than a rotating electrode.
Determination of Tungsten in Titanium Metal. E. W. BEITER, Westinghouse Research Laboratories, Chemical Department, East Pittsburgh, Pa. Conditions for the determination of tungsten in titanium metal using or-benzoinoxime were given, also results of analyses by the method.
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Solvent Extraction in Steel Analysis. Conditions for Removal of Iron(1II) a s Thiocyanate Complex. LABEN MELNICK:Jones & Laughlin Steel Corp., HENRYFREIGER, University of Pittsburgh, AND H. F. BEEGHLY, Jones & Laughlin Steel Corp., Pittsburgh, Pa. This paper dealt with use of n-butyl phosphate as a solvent for the extraction of iron(II1) thiocyanate. The previously observed (Aven and Freiser) extractability of iron thiocyanate by n-butyl phosphate has been subjected to a thorough study to determine the relevant factors governing the extraction. The effects of temperature, pH, concentration of iron, and ratio of thiocyanate to iron were investigated. In addition, the possibility of using carbon tetrachloride solutions of n-butyl phosphate rather than the ester itself was studied. It was found that a suitable Bu~POI-CCLmixture could be used which, in addition t o quantitatively extracting the iron was heavier than the aqueous phase, permitting greater convenience in extraction. The results of this study have been applied to the problems of steel analysis. The extraction of the thiocyanates of other metals by means of butyl phosphate was also discussed. Statistical Study of Reliability of Analytical Methods in an Industrial Research Laboratory. 0. D. SHREVEAND H . B. WAGNER, Marshall Laboratory, E. I. du Pont de Nemours & Co., Inc., Philadelphia, Pa. This paper described an actual case history in the application of statistical methods to the problem of estimating confidence limits and establishing sources of variability for analytical methods in a practical industrial analytical situation. In most laboratories the analytical data employed in guiding research, establishing conclusions, and affording a basis for important decisions are supplied by an analytical division functioning as a service group for the research and development personnel. The importance of being able to attach quantitative estimates of reliability to the data supplied by such a group is obvious. In the usual industrial situation, a given analytical result is subject not only to the variability inherent in the method used but to variability between different analysts and between different times of analysis within analysts. Thus, realistic estimates of precision in such a situation must be calculated from replicates obtained on the same sample by a representative group of analysts, each running the analysis at different times. Fortunately, as demonstrated in the paper, statistical methods make possible the establishment of useful reliability estimates with a minimum outlay of time and manpower. The plan followed, the statistical techniques employed, and the benefits derived were described and illustrated by examples from the study. Emphasis was placed on certain pitfalls to be avoided by the analytical chemist in dealing with the relatively unfamiliar concepts and methods of statistical analysis, particularly as regards the blind adherence to “statistical recipes” which may lead to self-delusion and false conclusions. Spectroisotopy, a New Field of Spectroscopic Endeavor. J. R. MCNALLY, JR., Stable Isotope Research and Production Division, Oak Ridge National Laboratory, Oak Ridge, Tenn. Optical spectroscopic methods are being applied with increasing effectiveness to the evaluation of isotopic constituents of materials. This paper discussed the problems encountered in the use of atomic isotope spectra, the general theories of such spectrum differences, and some of the analytical results obtained. The extension of spectroisotopic methods to include the intermediate mass elements which generally show relatively small isotope shifts in atomic spectra was discussed briefly. Application of direct-reading photoelectric techniques, sharp line excitation sources, high resolution spectrographs, beam splitting devices, and careful data control indicates that the spectroisotopic method approaches the precision of mass spectrometer techniques and has the advantage of considerable saving in sampling time.
Use of Discharge Tubes in Spectrochemical Analysis. FRED, Argonne National Laboratory, Chicago, Ill.
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A Schuler-Gollnow type of hollow cathode tube has been developed which facilitates sample exchange and recovery. This source has certain advantages for the analysis of submilligram samples, such as long sample life, permitting multiple exposures; sharp lines, making it suitable for isotope assay; the ability t o excite nonmetallic impurities; and the ease of shielding and recovery of radioactive samples. These properties are also valuable for fundamental spectroscopy. The low excitation is a useful supplement t o the high excitation of the Paschen type of hollow cathode and of the spark. The operating characteristics of this source were described and some applications t o solid samples cited. Experience in the analysis of gas mixtures and isotope assay of gas samples by means of the electrodeless discharge tube was also described, and other sources were mentioned.
Some Applications of the Photoelectric Recording of Spectra to the (now a t Study of Electrical Discharges in Gases. T. M. DONAHUE University of Pittsburgh), Johns Hopkins University, Baltimore, Md. The continuing contribution of spectroscopy to other branches of physics can be illustrated by its recently enhanced usefulness in the study of the fundamental properties of electrical discharges in gases. Spectroscopic examination of the light emitted from the various glowing regions of a gas discharge has always been in principle a primary method of realizing the internal properties of the discharge. Practical difficulties have limited its applicability seriously until the recent advent of the practice of rapid direct recording of spectra with the aid of photomultiplier tubes. For example, in the case of mercury vapor glow discharges, insight may be had into the mechanism of moving striations which travel through the discharge by comparing the behavior of the 2537 line with other higher lying combinations as functions of time and position. This involves observing the lines from different parts of the discharge tube with a photomultiplier and display of the multiplier output on the screen of an oscillograph. Evidence thus obtained indicates that cumulative ionization very probably underlies the mechanism of striation movement. In a glow discharge through deuterium, which can exhibit both stationary striations (striae) and moving striations, measurement of rotational temperatures by means of time average direct recording of lines in the 0-0 Fulcher band in various parts of striae leads to the conclusion that the light in the bright part of moving striations and of striae comes from freshly excited molecules not yet in equilibrium with the rest of the gas while the light from the darker regions between striae and moving striations must come from D 2-electron recombination.
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Radioisotopes and Solvent Extraction. GEORGEH. MORRISON, Physics Laboratories, Sylvania Electric Products, Inc., Flushing, N. Y. Two techniques which have become increasingly important in analytical chemistry in recent years are the use of radioisotopes and solvent extraction. This paper showed how each of these analytical tools may be used to develop a further understanding of the other. I n the separation and use of radioactive substances it is frequently necessary to isolate radioisotopes which do not contain detectable amounts of stable isotopic material. These carrier-free isotopes are generally obtained in amounts which are detectable only by their characteristic nuclear radiations, and consequently special methods of separation are required. Solvent extraction is frequently the most satisfactory method of separating a given radioactive species from nonisotopic substances which may be present in either macro or micro amounts. Besides the role of extraction in the purification and isolation of radioisotopes, the use of tracers in solvent extraction studies has been invaluable. The obtaining of fundamental distribution data, the study of completeness of separations, and investigations of reaction mechanisms such as chelation, intersolvate exchange, etc., are a few applications of this method. Specific examples of the role of solvent extraction in radiochemistry, as well as the use of tracers in extraction studies, were presented, followed by a brief discussion of the laboratory methods of extracting and measuring radioisotopes. Determination of Small Concentrations of Indium by Radioactivation. J. E. HUDGENS AND L. N. NELSON, U. S.Atomic Energy Commission, New Brunswick, N.J. A radioactivation method for the determination of less than 1 p.p.m. quantities of indium in aluminum and thallium was described. When the nuclear reactor is used as the source of neutrons, and indium 114 (In11’) is the isotope detected, the ultimate sensitivity of the method is 10-11 gram. Data illustrating the use of a radium-beryllium source to produce indium 116 as a means of determining microgram quantities of indium were given. The chemical steps required in the performance of the analysis are simple and can be completed within a short time. Recent Developments in Mass Spectrometry. ALFRED0. NIER, University of Minnesota, Minneapolis, Minn. At the present time practically all mass spectrometers in use employ sector (including 180’) magnetic fields for separating ions of different mass. I n the past few years other types of instruments have been proposed. These include devices which operate on the time of flight principle. Several different styles have been suggested. Also, a successful high resolution double-focusing mass spectrometer has been constructed. While the particular instrument has been used exclusively for measuring atomic masses, it appears to have real possibilities as an analytical tool.
ANALYTICAL CHEMISTRY
598 Appearance Potential and Ionization Probability by Monoenergetic Electrons. R.E. FOX,W. M. HICKAM, T. KJELDIAS, AND D. GROVE, Westinghouse Research Laboratories, East Pittsburgh, Pa. The mass spectrometer has been used to study ions formed in a field free region by electrons of well defined energy. Without reference to a standard, the appearance potential of a number of gases was measured to within 0.1 electron volt of the spectroscopic value. A straight-line ionization probability curve was found near the appearance potential which shows the “tailing” generally observed t o be due to spread in electron energy. High Frequency Ion Resonance Mass Spectrometer. G. JERNAGeneral Engineering Laboratory, General Electric Co., Schenectady, N. Y. The ion resonance tube is a promising newcomer in the field of mass spectrometry. Its construction is extremely simple, requiring no critical alignments, as encountered in conventional mass spectrometers. Recent developments and applications of the ion resonance mass spectrometer were discussed, together with advantages and limitations of the tube. KOFF,
Dual-Purpose Mass Spectrometer. A. P. GIFFORD,SIBYLM. ROCK,AND P. S. GOODWIN, Consolidated Engineering Corp., Pasadena, Calif.
A new mass spectrometer was described which can be used for the analysis of mixtures of gases and liquids and for direct measurements of isotope ratios. Novel design features were discussed, including an automatic recording amplifier, an isotope-ratio recording system, a refrigerant-free vacuum system, and a motor-driven magnetic scanning mechanism. Operation of the instrument was also discussed, and some typical analytical results were presented. Mass Spectrometer-Digital Computer Combination for Automatic Analysis. W. S. YOUNG, J. H. RAMSER, R. A. BROWN, F. W. MELPOLDER, G. R. C.&RRICK, J. SPONTAK, AND C. E. HELDISGTON, Atlantic Refining Co., Philadelphia, Pa. This paper reported progress on a development which has been under way for some time utilizing a digital computer of special design along with necessary associated apparatus to make mass spectrometer operation and computation of results completely automatic. All operations from the time a sample is introduced into the mass spectrometer until its composition appears typed on a sheet of paper are automatic, thus eliminating both record reading and hand computation. It is anticipated that only one operator will be required to supervise the functioning of the mass spectrometer, the computer, and associated apparatus. An analysis of a mixture containing twenty components is expected to take less than 10 minutes from the time a sample is introduced. Automatic Conversion of Mass Spectra to Digital Form.
SIBYL
M. ROCK,CLIFFORD E. BERRY,AND R. L. SINK,Consolidated Engineering Corp., Pasadena, Calif. Apparatus now under development for obtaining either IBM cards or a typed spectrum directly from the mass spectrometer during a run was described. Up to 40 peaks may he programmed, and each read to 1 part in 1000, full scale. An attenuator operates automatically to indicate multiplying factors of 1, 3, 10, 30, thus maintaining a dynamic range of 0.0 to 3000 divisions. Scientific Solution of Mysteries. JOSEPH D. NICOL,Pittsburgh and Allegheny County Crime Laboratory, Pittsburgh, Pa. A discussion of the scientific approach to criminal activity, illustrated with material from actual cases. Lie detection, firearms identification, comparative micrography, microscopy, and chemistry were included in the presentation. Some Fundamental Aspects of Spectrochemical Processes Encountered in Determining Major Constituents. LESTERTt’. STROCK, Strock Laboratories, Inc., Saratoga Springs, N. Y. The spectrochemical determination of major constituents in rocks, minerals, and other nonconducting solids permits diluting samples to a degree not feasible in trace element analysis methods, which affords opportunity of observing the buffering effect of large amounts of a diluting agent, and deducing details of the arcing process in terms of familiar physical and chemical reactions. The first ionization potential of germanium (8.13~)is much closer t o most other metals (4.5-8.5~)usually determined, than to carbon (11.26~)used as electrodes in d.c. arcs. Germanium metal is liquid in the range 960-2700’ C., which covers a large portion of the tem-
perature range of the liquid state of many other metals. Both facts were concluded to explain the observed high reproducibility and regularity of impurity line emission in d.c. arc germanium metal spectra. Germanium metal was, for these reasons, tested as a diluting agent for determining major constituents in silicates. Samples diluted to 10% with germanium provide an arc gas rich in one metal or with germanium atoms and ions dominating the arcing process. At the same time the particles remain in a homogeneous and quiet liquid state until completely volatilized. The value of these characteristics has been tested for an arcing mixture consisting of samplegermanium metalcarbon in ratio 1:9:20 for the elements Ca, Mg, Fe, AI, Si, Mn, (Ti) as major constituents in silicates. The great number of lines measurable for major constituents has also permitted a comparison of the suitability of various lines for spectrochemical calibration with their spectroscopic origin. The choice of lines for quantitative analysis remains dictated largely by practical considerations, such as instruments available in a given laboratory, optimum spectral range for including a desired combination of elements, etc., rather than on a deliberate choice of lines from identical or comparable energy levels in the atoms to be determined. Effect of Changing the Conditions of the Light Source upon the Influence of Extraneous Materials in Spectrochemical Analysis. D. ANDRYCHUK AND C. MCMULLEN, Diamond Alkali Co., Painesville, Ohio. A light source was employed in which the volatilization of the sample could be controlled independently of the excitation. This source was used to study the influence of extraneous materials upon the line intensity ratios. For the samples studied, it was observed that the extraneous material affects the mechanism of volatilization more than the mechanism of excitation. Operating the light source at a temperature of volatilization above the boiling points of the constituents of the sample and at high excitation energies as obtained from a low inductance reduced the influence of extraneous materials. Analysis of Photographic Emulsion Calibration Using a Step Sector. J. SHERMAN AND M. SLAVIN, Philadelphia Naval Shipyard, Naval Base, Philadelphia, Pa., and Brookhaven National Laboratory, Upton, N. Y. The method of establishing a time-based characteristic function of a photographic emulsion using a logarithmic step sector was considered. A linear difference equation of first order with constant coefficients may be derived relating time, sector constant, number of steps, and a general response function R(t). This equation is readily summed with analytical solutions and transformations of R derived to yield linear equations for the characteristic function of the emulsion. The geometry of the solutions for various transformations of R was discussed. The theory was applied to the calibration of two types of emulsions using commonly used forms of R such as transparency, opacity, density, Seidel function, as well as other admissible choices. The inherent difficulty of interpretation of experimental results was discussed and shown to he due to the nonlinearity of the transformations. GE Sun Lamp for Emulsion Calibration. A. J. MITTELDORF, Armour Research Foundation of Illinois Institute of Technology, Chicago, Ill. Calibrating film to obtain the gamma vs. wave-length relationship and the characteristic curve at a particular wave length has always met with many difficulties. Among the causes of these is the source of radiation. The General Electric Type RS sun lamp fulfills many of the criteria for an ideal source of radiation for plate calibration. It emits a number of lines well distributed in the region of 2650 to 4350A. It is comparatively simple to obtain lines which are uniform along their length, which makes the lamp extremely useful for calibration based on step-sector methods. The lamp is inexpensive, selling for $8.50, and can be operated directly from a 115-volt a.c. line. As it is made in large numbers, it may be possible that the intensity ratios of some of its lines will he reproducible from lamp to lamp. This would make the lamp exceedingly valuable as a reference source of radiation. This paper gave data on the use of the RS sun lamp for plate calibration. The uniformity of intensity along the length of a number of lines was illustrated. The application of the two-line method of calibration at several wave lengths was shown. The effects of line voltage variations were given. Internal Standard Properties of Undispersed-Selective Filtered Radiation. J. H. ENNS,Engineering Research Institute, University of Michigan, Ann Arbor, Mich. In spectrochemical analysis the importance of internal standards is well known. Photographic or direct-reading methods employ a
V O L U M E 2 4 , NO. 3, M A R C H 1 9 5 2
599
minute concentrations, have profound effects on biochemical funetion. Their study has been greatly facilitated by the developments of analytical chemistry, particularly quantitative emission spectrography. Their biochemical role is being explored with increasing interest; and through the advent of new techniques, hopes for their understanding have been increased. The paper is intended to be a survey of the present status of the Effect of Argon and Argon-Helium Mixtures on D.C. Arc. 5. JAMES field and of the potential contribution of the analyst to it. ADELSTEIN AND BERTL. VALLEE, Department of Biology, Massachusetts Institute of Technology, Cambridge, Mass. Electrochemical Method for Oxygen Determination in Gases. Studies were made of the effects of argon, helium, and argonLW. G . J a c o s s o ~ ,Mine Safety Appliances Co., AND J. T. RYAN, helium mixtures on the volatilization and line intensities of several Memorial Laboratory, Pittsburgh, Pa. elements studied in the d.c. arc. -4 biological matrix was employed. Early observations indicated that the time required for arcing several A number of attempts were maple during the last two decades by elements to extinctiqn increased logarithmically with increasing convarious authors to develop an oxygen detector based on a primary centrations of argon in helium. The logarithmic increase in the mean galvanic oxygen electrode as well as on a depolarization electrode. arcing time of 9 elements (15 lines) was determined a t three different Recent claims of absolute methods using such electrodes were disconcentrations: 1330, 333, and 133 p.p.m. There was an approxicussed and the advantages of the depolarization type versus primary mate linear increase of background intensity with time in all instances. type oxygen electrodes set forth. The basic features of the Mine Employing the mean arcing times so determined, as well as those Safety Appliances Co., oxygen indicators using such electrodes were calculated for lower concentrations by extrapolation, the variations of described and photographs of mechanical and electrical details shown. certain line intensities were studied in different argon in helium mixThe performance of the instruments with respect to required operatures at elemental concentrations of 67, 13, 6.7, and 1.3 p.p.m. tions, maintenance, sensitivity, accuracy, and influence of contamiMarked enhancement of certain element lines was shown with high nants was described. argon concentrations in the elemental concentration range studied. The enhancement of these lines and the requirement for optimum signal to noise ratio are being determined. Application of Molybdenum Catalyzed Reductions to Determination of Molybdenum, Chlorate and/or Perchloiate, Nitrate and/or Nitrite, and Possibly to Other Irreversibly Reduced Oxy Ions or Determinations of Trace Elements by Combining Chemical Oxygen-Containing Materials Such as Nitro-organic Compounds. Enrichment and Spectrochemical Methods. G. E. HEGGEN, Albany G . P. H b I G H T , JR.,AND ALAN REYNARD, Department Of Chemistry, A N D L. W. STROCK, Saratoga Springs Medical College, Albany, ii’.P., The George Washington University, Washington, D. C. Commission, Saratoga, N. Y. Chlorate and perchlorate in 5 N sulfuric acid are each reduced The determination of trace elements usually necessitates conversion smoothly to chloride in the presence of molybdate by electrolysis at of the sample t o Some form more amenable to spectrochemical methmercury cathodes, in the presence of amalgamated zinc or of stannous ods of analysis. This is particularly true when widely different types ion. Advantage is taken of the fact that perchlorate is not reduced of samples such as waters, snow, rocks and minerals, soils, coals, by zinc or stannous ion in the absence of molybdate to determine both petroleum, plant materials, and biological tissues and fluids must be perchlorate and chlorate in a mixture. analyzed for the same elements and where it is desirable to use the The electrical reduction yields a large catalytic polarographic wave same spectrochemical calibration. This conversion frequently profor molybdenum in perchloric acid, which may be used for the quantivides an opportunity to effect an enrichment of the trace element contative estimation of molybdate without previous separation in any tent at the same time. This enrichment may be accomplished by soluble material. evaporating, ashing, or dissolving the sample, followed by chemical Nitrate and nitrite in 5 N sulfuric acid are reduced t o N20 by stanseparation. Oxides are a common end product of such concentranous ion a t room temperature in the presence of molybdate, only tion-enrichment procedures. nitrite being reduced at room temperature in the absence of molybThe following chemical separation methods have been used extendate. This makes analysis for both nitrate and nitrite in the same sively to effect enrichments prior to spectrochemical analysis: presolution possible. cipitation as hydroxides, sulfides, and by using organic complexing Preliminary studies indicate the stannous-molybdate reducing sysreagents such as cupferron, 8-quinolinol, and a combination of thiotem can be applied to other materials such as nitro-organic comanalide, tannic acid, and 8-quinolinol. Ignition converts all these pounds. precipitates to simple oxides which are convenient to analyze and Evidence was presented that tetravalent molybdenum is the calibrate for spectrochemical analyses. Additional separations and catalyst. enrichments can be effected by extraction with organic solvents, either of the sample dirertly or after complexing with other organic compounds. Universal Combustion System. A. N. OEMLER AND J. MITCHELL, The above methods have been applied to geochemical, agricultural, JR., Polychemicals Department, E. I du Pont de Nemours & Co., and medical research problems. Currently the 8-quinolinol, tannic Inc., Wilmington, Del. acid, and thioanalide precipitating method is being applied to concenA general method was desired for estimating small amounts of ortrating the elements Ag, 8 1 , Bi, Co, Cr, Cu, Fe, Mo, Ni, Pb, Sn, Ti, ganic matter in water. The usual wet-combustion systems for deterV, Zn, for spectrochemical determinat,ion of biological tissues and mining total carbon are not applicable to high boiling, but steamfluids for a cancer research project. distillable materials, as these are in part trapped in the condenser. Volatile compounds often are distllled from the reagent solution beSpectroscopic Determination of Metals in Silica-Alumina Cracking fore oxidation is complete. -4combustion system has been devised Catalysts. J. P. PAQLIASSOTTI AND F. W. PORSCHE, Research Dewhich overcomes these.difficulties. A spiral of glass rod is placed in partment, Standard Oil Co. (Indiana), Whiting, Ind. the condenser, and a slow stream of sulfuric acid is allowed to flow over the spiral to return steam-distillable organics to the combustion -4 spectroscopic method has been developed for the rapid and flask, containing sulfuric-chromic acld reagent. Organic vapors accurate determination of metals in silica-alumina cracking catalysts. escaping from the condenser are burned in a small copper oxide tube After dissolution of the sample with acid, the aluminum, iron, vanaa t 750’ C. The carbon dioxide is aerated through sulfuric acid and dium, nickel, copper, lead, and calcium in the resulting solution are Drierite scrubbers and collected in an Abcarite absorber, where it is determined spectrographically by either interrupted-arc or spark determined gravimetrically. excitation. Sodium is determined by means of the flame photometer. The solution of the sample obviates the effects of crystal form and ion linkage. Comparison on a similar basis of naturally occurring Determination of Arsenic in Canned Fruits. J. C. BARTLET, ETHEL minerals, synthetically prepared catalysts, and laboratory standards LIST, MARQARET WOOD,AND R. A. CHAPMAN, Food and Drug Labis therefore feasible. The method is capable of ready extension to the oratories, Department of National Health and Welfare, Ottawa, determination of additional metals as well as to the analysis of other Canada. solid-phase samples amenable to solution. When an attempt was made to apply the bromide distillation method of Magnuson and Watson to the determination of arsenic in Oligo- or Trace Elements in Biology. BERTL. VALLEE,Departcanned fruits, it was found that tin interfered seriously. Tin distills ment of Biology, Massachusetts Institute of Technology, Cambridge, and coprecipitates with arsenic in the distillate prior to estimation of Mass. the arsenic by molybdenum blue. This interference is eliminated by The paper was a general review of biological problems concerning extraction of the tin with cupferron before distillation. The distillathe so-called oligo- or trace elements. These elements, occurring in tion procedure was discussed and modifications were given.
reference line of an clement of relative constant concentration. In this paper direct-reading ratio measurements were compared when the reference signal is an internal standard line, the total undispersed radiation, or undispersed-selective filtered radiation. Ratio shifts due to changes in excitation parameters (spark source) were shown.
ANALYTICAL CHEMISTRY
600 Alkalimetric Determination of Phosphate after Separation of Calcium by Ion Exchange. B. H. KINDT(now at Schenectady Works Research LaboraLaboratory), E. W. BALIS,AND H. A. LIEBHAFSKY, tory, General Electric Co., Schenectady, N. Y. Upon being tested, the method of Helrich and Rieman gave results less precise than those reported [ANAL.CHEM., 19, 651 (1947)l. Precision was improved by replacing Amberlite IR-100 with Dowex 50, by careful expulsion of carbon dioxide, and by, using a glass electrode to permit precise location of the HzPOd- and HPO4-- end points, the difference between which yields the phosphate content of the sample. In the method as modified, retention of phosphate by the resin is negligible, but breakthrough of calcium can be detected. Systematic experiments showed that this breakthrough is not great enough to affect the phosphate determination. Larger amounts of calcium lead t o high results that could be attributed t o the precipitation of Caa(PO&. The use of the ion-exchange resin had no demonstrated effect on the precision of the titration, the standard deviation of which was near 1 part in 500 of phosphate under the best conditions. The precision attained being relatively high, it was conceivable that a correction might be required owing t o the position of the hydrolysis equilibria at the two end points. Calculations have shown that each of the true end points is displaced from the corresponding equivalence point in the direction of excess added base, but that the two displacements are almost identical, which makes the correction negligible.
Mass Spectra of Heterocyclic Nitrogen Compounds. G. L. COOK A. P. MARR,Bureau of Mines, Laramie, Wyo.
AND
The mass spectra of 25 heterocyclic nitrogen compounds have been obtained. As the spectra were to be used in this laboratory primarily for qualitative identifications, no extensive purification of the compounds was undertaken. The spectra were discussed and peculiarities in the patterns were pointed out. A method of introducing samples of pyridine bases to the mws spectrometer was described. This method is especially helpful when only micro quantities of the base are available. Mass Spectra of the Tetramethyl Compounds of Carbon, Silicon, Germanium, Tin, and Lead. VERNON H. DIBILXR,National Bureau of Standards, Washington, D. C.
Mass spectra of the Group IV tetramethyl compounds have been obtained with 70-volt electrons by using a Consolidated 21-103 mass spectrometer. The monoisotopic spectra were computed from the observed isotopic abundances of the metal atoms. The spectra are qualitatively similar. The most probable process is the dissociation of one methyl group. The relative stability of the molecule ion is lowest for neopentane and highest for tetramethyl silicon, decreasing irregularly from germanium to lead. A marked decrease in the number of dissociation products is apparent in proceeding from neopentane to tetramethyl tin. Tetramethyllead has only a few more ions. This decreasing probability of hydrogen dissociation is accompanied 2-(o-Hydroxypheny1)-benzoxazole as a Reagent for the DeterL. WALTERAND HENRYFREIBER, by a decrease in the formation of hydride ions and other ions formed mination of Cadmium. JOSEPH by intramolecular rearrangement. I n general, this would seem to Department of Chemistry, University of Pittsburgh, Pittsburgh, Pa. indicate an increase in the stability of bonds between carbon and hyThere was described a gravimetric method for the determination of drogen atoms with increasing atomic number of the central atom. cadmium based on the application of its reaction with 2-(o-hydroxyGood agreement was noted between the observed isotopic abunphenyl)-bensoxaaole. I t was found pomible t o determine from 1 to dances of silicon, germanium, tin, and lead after correction for hydride 80 mg. of cadmium to an average accuracy of 0.3 mg. By carrying ions and values reported by previous investigators from measureout the precipitation at a pH of 10.5 in a tartrate buffer, virtually all ments on inorganic halides. This gives support to the practical use interferences are removed. Of those ions studied, only nickel and of organometallic compounds for routine isotope abundance measure cobalt interfere seriously. Cadmium may be determined in the ments of elements that do not form volatile inorganic compounds. presence of copper by precipitating the latter with the reagent at a lower pH.
Two Rapid Methods for the Determination of Metallic Ions in
Gum Arabic. WILLIAMH. MARTIN,Harris-Seybold Co., Cleveland, Ohio. Gum arabic has many uses in lithography. The two largest usages are: as a light-sensitive coating for metallic lithographic plates, and as a hydrophillic protective film upon metallic surfaces of lithographic plates. Gum arabic, as received from the importer, contains considerable amounts of calcium, magnesium, and iron. These metals will precipitate in the ammoniacal solution in which form the gum for photosensitive coatings is used. In order to remove these undesirable metals, the gum is passed through ion-exchange columns and the gum arabic is converted to ammonium arabate. The gum arabic used as a protective film for the non image area of the plate is a water-gum solution of pH 4.3 with an appropriate preservative. In order for more efficient use of the ion exchange column, methods for metallic determination in gum arabic were developed: (1) a spectrographic method for qualitative analysis and quantitative determination, and (2) a rapid colorimetric method in which metallic ions are determined and calculated as a unit. By using these methods it is possible to pegregate the incoming shipments of gum, so the gum with low calcium or hardness content is converted to photosensitive coating and gum with higher content is used for protective usages. The effluent from the ion-exchange columns is also checked to determine the point of exhaustion of the resin. Coatings made in this manner have much more uniform physical specifications and lithographic characteristics than if they were made from untreated gum arabic. Extension of Mass Spectrometer Analyses to Various Nonhydrocarbon Molecules. FREDL. MOHLER, National Bureau of Standards, Washington, D. C. The Mass Spectrometry Section of the National Bureau of Standards has accumulated mass spectra of a number of the completely fluorinated light hydrocarbons, and the patterns of these compounds were discussed. The mass spectrometer has also been used to identify some complicated compounds that have been synthesized here and to look for new reaction products. Experience with some of these compounds was described.
Determination of Benzene, Cyclohexane, and Methylcyclopentane in Light Naphthas by Mass Spectrometer. SEYMOUR MEYERSON, Standard Oil Co. (Indiana), Whiting, Ind. A procedure has been established for the determination by mass spectrometer of benzene, cyclohexane, and methylcyclopentane in light naphthas containing no olefins. Benzene is determined directly from the peak at m/e 78. Interferences on the peaks at m / e 69 and m/e 84, which are used to determine cyclohexane and methylcyclopentane, must be taken into account. After careful fractionation to remove dimethylcyclopentanes, which are responsible for the most serious interferences on these peaks, the C6 naphthenes can be determined without regard to the presence of other compounds.
Benzene, Toluene, Xylene, Ethylbenzene, Cumene, and Total C, Aromatics Determination by Mass Spectrometry. J. H. SHIVBLY AND J. J. MORELLO, The Texas Co., Beacon, N. Y . A method was described for the determination of benzene, toluene, total xylenes, ethylbenzene, cumene, and total Cs aromatics. The C.5, CS,CSaromatics and the cumene are determined on a single distillation cut. A very careful distillation is not needed for isolating the cut, since any normal propylbenaene which may remain in it will not interfere but will merely be determined incidental to the determination of the lower boiling aromatic hydrocarbons. The sum of the other CSaromatics is determined on a portion of the bottoms from the distillation or, if preferred, total CS aromatics may be determined using a portion of the original naphtha sample. Mass Spectrometric Method of Resolving Normal and Isomeric Paraffins in Complex Hydrocarbon Mixtures. H. SOBCOV, SoconyVacuum Laboratories, Paulsboro, N. J. Methods previously reported by others have shown how complex hydrocarbon mixtures in the gasoline and kerosene ranges may be considered to have four major mass spectrometric types and how each type may be closely estimated. One of these types embraces the aliphatic paraffins, but there has not existed any simple and rapid method of quantitatively determining the breakdown of this portion into the %-paraffinand total isoparaffin contributions. By an extension of the type analysis this further resolution can be accomplished by mass spectrometry techniques. While the method is not rigorous, it has been found useful in most instances encountered to date.
601
V O L U M E 2 4 , NO. 3, M A R C H 1 9 5 2 Correlation of Mass Spectra of Alcohols through Cn. R. A. FRIEDEL A N D A. G. SHARKEY, JR., Bureau of Mines, Bruceton, Pa. The mass spectra of 37 alcohols ranging from methanol to undecanol have been obtained using a Consolidated Model 21-103 mass spectrometer. Major peaks have been related to the structures of the compounds. The following general rules hold for the alcohols investigated: 1. For primary straight-chain, primary branched, and naphthenic alcohols, the first and second major peaks below the parent peaks result from loss of water followed by loss of a hydrocarbon group. 2. For secondary straight-chain, secondary branched, and tertiary alcohols, the first and second major peaks below the parents result from loss of a hydrocarbon group followed by loss of water. The loss of hydrocarbon groups results from splitting at the carbinol group. These correlations can be used effectively in the identification of an unknown alcohol. A rapid method of obtaining the total Ca through Cs normal alcohols in a mixture containing hydrocarbons was described. Results obtained on synthetic blends containing octanol and lower alcohols were also presented. A Decade of Ultraviolet Absorption Spectroscopy. Sun oil Co., Norwood, Pa.
E. J. ROSEN-
B.4UM,
Trends in the application of ultraviolet spectra to analytical problems and recent developments in the instrumentation for ultraviolet spectroscopy, including the vacuum region, were discussed. Some attention was given to continuous ultraviolet analyzers. The present situation concerning terminology and presentation of spectral data was reviewed. Iodobenzene and Its Derivatives as Examples of Abnormal Chromophoric Interaction in the Benzene Series. L. DOUBAXD J. M. VANDENBELT, Parke, Davis & Co., Detroit, Mich. A number of new examples were given to confirm the previously established correlations of benzene spectra in its disubstituted derivatives. Against this background as "normal," iodobenzene and its derivatives were studied as an example of combination of the benzene chromophore with another absorbing in the same wave-length region. The pattern which emerges is that the most effective chromophoreLe., iodine in iodobenzene-is dominant in derivatives until displacement of the spectra by substitution of the benzene nucleus removes the primary band ea. 25 mp beyond the original maximum of iodobenzene at 227 mg, -4t longer wave length, iodine as a substituent exerts on the first primary band of benzene a displacement effect very much comparable to that of the halogens, chlorine, and bromine. Some Potentialities of the 200- to 230-Millimicron Range in Biochemical Studies. LEOJ. SAIDEL, Chicago Medical School, Chicago, Ill. Although the region of the spectrum from about 200 mp to 230 mp has been fairly accessible for many years, and a few branches of chemistry have made extensive use of it, it has been completely ignored by the vast majority of biochemists. One of the principal reasons for this is probably the impression that it is a region of generalized absorption or end absorption and therefore of no interest. Upon investigation it was found that this end absorption displayed by many compounds with very little absorption in the visible and ultraviolet region above 230 mp, frequently contains a band with a relatively high extinction coefficient. Moreover, in many instances where the end absorption contains no obvious features above 200 mp it is sufficiently high and characteristic a t a given wave length to be of analytical interest. The spectra of a large number of organic compounds of biochemical interest, which heretofore have not been given much consideration in the 200 t o 230 mp region, were presented and very briefly discussed from an empirical point of view. Particular attention was given to nitrogen- and sulfur-containing compounds.
Use of Micrometer Baly Cells with Beckman and Cary Ultraviolet Spectrophotometers. ROBERT C. HIRTA N D FRAWK T. KING,American Cyanamid Co., Stamford, Conn. Micrometer Baly cells with quartz windows, manufactured by Hilger for use with Spekker photometers, have been adapted for use with the Beckman Model DU and the Cary Models 10 and 11 ultraviolet spectrophotometers. Simple adapters to hold the cells in these instruments were described. The variation of the cell light path length rather than the concentration permits a speedier scanning of the spectrum and avoids apparent Beer's law deviations on dilution. These advantages outweigh the higher initial cost.
A study has been made of the accuracy of these Baly cells as compared t o insert-type and conventional cells using the molar absorp tivity of the major band of pyrazine. The accuracy of the Baly cells was found to be sufficient for analytical work except at very short lengths.
Spectrophotometric Practice with Absorption Cells of Extremely Short Path Length. J. M. VANDENBELT, CAROLA HENRICH,AND SHIRLEY L. BASH,Parke, Davis & Co., Detroit, Mich. The usual range of spectrophotometric practice can be extended in certain applications by the use of absorption cells of extremely short path length. As a result of diminished solvent absorption with these cells, spectra may be read to substantially shorter wave length than with cells of standard dimension, and it is possible to make determinations otherwise blanked out. The accuracy of readings in these ranges is increased as a result of the smaller slit widths employed for instrument balance and the corresponding reduction in scattered radiation. With the quartz 0.020-cm. cells used in these experiments, a fifty times dilution in solute concentration is automatically effected. This often permits readings directly in any part of the spectrum where further addition of solvent is to be avoided, or when only minimal quantities of a special solvent are available.
Ultraviolet Absorption Analyses for Cn and Clo Aromatics. hf.4~S.NORRISAND NORMAN D . COGGESHALL, Gulf Research & Development Co., Pittsburgh, Pa. THEW
An ultraviolet absorption method has been developed for the group-type analysis of aromatics in the 150' to 180' C. fraction of gasolines. I t has been found that all the monosubstituted aromatics boiling in this range possess very similar spectra in both the range and intensity of absorption. These aromatics are hence regarded as a single class and an average spectrum is calculated for the group. It was further found that all ortho and meta disubstituted aromatics possess very similar spectra which are substantially different from those of the monosubstituted ones. This allowed these to be grouped in a single class and an average spectrum to be computed for them. In the boiling range of interest, there are only three para-substituted aromatics. Two of these may be classified as a single group, whereas the third must be determined independently. All the aromatics in this boiling point range hence fall into one of four classes. Investigations showed that measurements a t four selected wave lengths allow multicomponent analyses to be made for the above classes of aromatics. Results of tests on synthetic samples blended to simulate gasoline fractions were given and discussed. illso the classification of aromatics in catalytic cracked, thermally cracked, and straight-run gasolines was discussed.
Ultraviolet Spectrophotometric Study of Eugenol-Isoeugenol System. V. C. VESPEAND D. F. BOLTZ,Wayne University, Detroit, Mich. Eugenol and isoeugenol have characteristic ultraviolet absorption spectra amenable to the spectrophotometric analysis of a two-component system. The optimum wave lengths for absorbancy measurements and molar absorbancy indexes were determined. The double bond in conjugation with the benzene ring in the case of isoeugenol gives an absorbancy maximum at a lower wave length than for eugenol and a much larger molar absorbancy index. The simultaneous spectrophotometric determination of eugenol and isoeugenol was possible in synthetic mixtures in which the eugenolisoeugenol ratio varied from about 0.5 t o 50, the concentration of eugenol being lo-' to 10-6 molar.
Ultraviolet Absorption Studies of Factors Affecting the Fading of Humic Acid Solutions. HAROLDL. LOVELL AND CORLISS R. KINNEY, School of Mineral Industries, Pennsylvania State College, State College, Pa. The decrease in absorption of alkaline solutions of humic acids derived from oxidized bituminous coal has been studied further. This change proceeds slowly in the absence of light and gaseous or dissolved oxygen. The change is enhanced by the addition of an oxidant, but the rate of fading is increased manyfold by exposure of the solution to radiant energy. Other variables studied included solute concentration, solvent concentration, container material, and temperature. Studies on the substances recovered after extensive fading show that major changes have occurred in the properties and composition of the original humic acids.
602 Titrations in Nonaqueous Solutions. ERNESTG. WOLLISHAND CHARLESW. PIFER,Products Control Laboratory, Hoffmann-La Roche, Inc., Nutley, N. J.
-4survey of the field of nonaqueous titrations reveals three major groups, which may be classified into: Titrimetry in an acid solvent system, comprising acidic, weakly acid, and neutral solvents, the latter rendered acidic by the titrant perchloric acid in glacial acetic acid. Substances that can be titrated in such a system are: primary, secondary, and tertiary amines, bases, amino acids, salts of inorganic cations, alkali metal salts of weak monobasic acids, carboxylic acid salts, and salts of organic bases. Titrations in a neutral solvent system may be performed with perchloric acid in dioxane, or with sodium or lithium methoxide in methanol-benzene, depending upon the substance t o be titrated. A basic solvent system, using such solvents as acetonitrile, dimethyl formamide, ethylenediamine, butylamine, pyridine, or morpholine, can be useful for the titration of carboxylic acids, acid chlorides, acid anhydrides, enols, imides, nitro compounds, mercaptans, oximes, sulfonamides, and salts. It was shown how today compounds can be titrated with ease in nonaqueous media, titrations that could not be performed in water, and including compounds for which only time-consuming and tedious assay methods existed. Thus, titrimetry in nonaqueous media, with its simplicity, speed, and precision, can function as a valuable analytical tool, permitting substantial reductions in unit cost per analysis. These titrations can be conducted either potentiometrically or using visual indicators, the proper selection of which is governed by the substance to be titrated and the titrant to be employed. Electrode systems, indicators, titrants, applications, and limitations were reviewed, as well as accuracy and precision obtainable. Anodic Voltammetry of Phenol. JOHN F. HEDENBURG AND HENRY FREISER, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pa. Phenol can be oxidized a t a micro platinum anode yielding a current-voltage curve similar to the conventional polarographic wave. A reproducible half-wave potential, shown to be a function of pH, is obtained. At a pH of 9, the half-wave potential has a value of 0.52 volt. An equation has been derived which closely describes the pH dependence of the half-wave potential. A plot of logI/(Id - I ) PS. E gives a straight line indicating a polarographically reversible oneelectron oxidation to the phenoxide free radical. The diffusion current is found t o be closely proportional to the concentration and essentially independent of the pH. This is a new method of analysis for phenol and will also permit an electromotive series t o be constructed for phenols and enols whose over-all oxidation is irreversible. Comparison of the Analytical Behavior of the Chelates of 2(0Hydroxyphenyl)-benzothiazole and 2(o-Hydroxyphenyl)-benzothiazoline. ROBERT G. CHARLES . ~ N DHENRY FREISER, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pa. This report dealt with chelating tendencies of two reagents developed in this laboratory, 2(o-hydroxyphenyl)-beneothia~ole(I) and 2(o-hydroxyphenyl)-benzothiaroline(II). The analytical behavior of these reagents is markedly different, reagent I1 reacting with many of the common divalent and trivalent metallic cations, while the reactions of I resemble those of the analogous benzoxazole and are restricted to a few of the divalent metals. A study of the stabilities of metallic chelates of I and I1 reveals a stability sequence for the divalent metals unlike that found for most other reagents. The experimental findings were interpreted in the light of steric influence, basicity of reagent, and ring size. Relation of Structure to Analytical Behavior of Some Substituted 8-Quinolinols. W. DWIGHT JOHNSTON AND HENRY FREISER, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pa. The stabilities of a representative group of metallic chelates of reagents analogous t o 8-quinolinol have been determined. An evaluation of the stabilities of chelates of 2-methyl-8-quinolino1, which, Merritt and Walker had shown, did not react with aluminum, has shown unusually low stabilities in the cases of its copper(I1) and nickel(I1) chelates. This is taken to be a more subtle manifestation of the steric hindrance of the 2-methyl group, which has been used to explain the nonreaction of aluminum with this reagent. Similar measurements have been carried out on the 4-methyl-8-quinolino1, in which the methyl group is not in a position to exert any blocking influence. The chelating tendencies of 2-(o-hydroxyphenyl)-quinoline and 1-(0-hydroxyphenyl)-isoquinoline,which should form six-membered ring chelates analogous to those of 8-quinolinol, were investi-
ANALYTICAL CHEMISTRY gated. The results lead one to the conclusion that five-membered rings are more stable than six-membered rings. 2-(o-Hydroxyphenyl)quinoline did not chelate Tith any of the metals tested under the conditions of the experiments. The isoquinoline analog did chelate but formed chelates which were much less stable than those of 8quinolinol. Effects of Solvents upon the Potentiometric and Visual Titration of Organic Acids, Bases, and Salts in Nonaqueous Medium. CHARLES W. PIFER,MORTONSCHMALL, AND ERNEST G. WOLLISH,Products Control Laboratory, Hoffmann-La Roche, Inc., Nutley, N. J. The sensitivity of nonaqueous titrations of organic acids, bases, and salts can be enhanced by proper selection of solvents. Thus it is possible to determine compounds having acidic or basic groups of different ionization constants in presence of each other. An apparatus for potentiometric titrations in chloroform, benzene, ethyl acetate, alcohols, etc., was described. Titrations using 0.001 N titrants have been conducted both visually and potentiometrically. New Technique for Extraction and Titration of Salts of Organic Bases and Acids. MORTONSCHMALL, CHARLESW. PIFER, AND ERNESTG. WOLLISH,Products Control Laboratory, Hoffmann-La Roche, Inc., Nutley, N. J. Two new simple types of apparatus for the semiautomatic liquidliquid extraction of acids or bases were described. One is for extraction with solvents lighter than water and the other for solvents heavier than water. The extracted compounds are titrated directly in the solvents, using nonaqueous titrants. This technique is extremely useful for the extraction of the desired components from organic salts, and can effect great savings in time. A modification of the apparatus permits saponification or acid hydrolysis prior to the extraction. Determination of p-Propiolactone Purity. WILLARD P. TYLERAND DONALD W. BEESING,B. F. Goodrich Research Center, Brecksville, Ohio. p-Propiolactone in the presence or absence of aliphatic acids and other normally expected impurities may be determined by allowing it to react with sodium thiosulfate in a properly buffered solution, and titrating the excess thiosulfate with iodine. Some impurities may be determined by conventional methods. The standard deviation of the method is less than 0.2% for samples above 80% purity and increases somewhat for less pure samples. The accuracy of the method has been checked by determination of purity by freezing point measurements using a thermistor element as a temperature-measuring device. The chemical method gives results approximately 0.5% lower than the physical method, as is expected from reaction rate considerations. Quality of Water Produced by Ion Exchange. A. C. REENTSAND J. F. WANTZ, Illinois Water Treatment Co., Rockford, Ill. Certain analytical determinations require water of a quality which is not easily attainable by distillation methods. With the advent of synthetic resins having base exchange properties, it is now possible to remove from water by a suitable combination of these resins practically all ionizable solids and gases. One resin substitutes hydrogen ion for the cations, another substitutes hydroxyl for the anions. The paper covered a brief discussion of the quality of water produced by the three basic types of deionizing units-namely, two-bed deionizers with weak base anion resins, two-bed deionirers with strong base anion resins, and mixed-bed deionizers. The uses and limitations of the treated water from each of the above types of units for research and analytical laboratory applications were given.
Use of Variable Reference Spectrophotometry in Qualitative Analysis. J. H. JONES AND L. S. HARROW, Division of Cosmetics, Food and Drug Administration, Washington, D. C. Identification of a single absorbing substance in a solution is usually a simple matter once the absorption spectrum is obtained. If, however, the solution contains two or more substances whose absorbancy curves overlap appreciably, positive identification of the components by inspection of the absorbancy curves is more difficult. In the application of the variable reference technique [Jones et aE., J . Assoc. Ofic.Agr. Chemists, 34, 135 (1951)],the absorbancy of the unknown solution is plotted against a reference solution containing one or more of the components known or suspected to be present in the unknown. Provision is made for readily varying the composition or concentration of the known reference solution. From absorbancy difference curves so obtained, it is frequently possible to identify
V O L U M E 24, NO. 3, M A R C H 1 9 5 2 the components of mixtures that cannot be resolved by ordinary spectrophotometric procedures. Application of the technique to problems encountered in the operations of the laboratories of the Food and Drug Administration was discussed. Use of the Beckman DU Spectrophotometer in the Region from 1 to LOCKER'HITE, JR., WALTERB. W A D E , .4ND WILLIS WOODRUFF, JR., Southern Research Institute, Birmingham, Ala.
2 Microns.
The Beckman quartz spectrophotometer, Model DU, is calibrated in wave lengths up to 2 microns. However, its photoelectric equipment has very low sensitivity beyond about 1 micron. In order to make the instrument useful in the very near infrared, its photoemissive tubes and amplifier have been replaced by a chopper for the light, a lead sulfide photoconductive cell, a tuned amplifier, a vacuumtube voltmeter, and a strip-chart recorder. Data indicative of the usefulness of the system as an analytical tool were reported in this paper. Evidence of the resolving power of the system was included. Water can be determined in organic materials (acetone, dioxane, ethyl acetate, methanol, and pyridine, for example) and in inorganic systems (fuming nitric acid, even if contaminated with salts from storage in stainless steel). Purification of reagent-grade carbon tetrachloride by distillation has been followed with this system to prove that the chloroform content was reduced below 0.01%. Small quantities of toluene in benzaldehyde have been determined with a precision of about 0.5%. Application of Matrices and IBM Techniques to the Analysis of Liquid Hydrocarbon Mixtures by Mass Spectrometry. H. SOBCOV, Socony-Vacuum Laboratories, Paulsboro, N. J. An investigation was made of the means by which rapid a n d accurate mass spectrometer analyses could be obtained for hydrocarbon mixtures found in the boiling range defined by the pentanes and toluene. Many of the observations from this study are general enough to be applicable to problems in mass spectrometry involving any other range of compounds. Mass spectral conditions which must be met and the limitations of the matrixes used t o obtain accurate results are cited along with specific examples. Direct-Reading Analysis of Steel Making Slags. hl. F. HASLER AND F. BARLEY,JR., Applied Research Laboratories, Glendale, Calif.
603 Ashes. C. H. ANDERSON AND C. D. BEbTTY, Research and Development Department, Babcock & Wilcox Co., Alliance, Ohio. Quantitative spectrographic methods for the determination of sodium and potassium in coal ash, tapped furnace slag, tube deposits, and fly ash were described. The two elements are determined on separate samples using a lorn amperage d.c. arc excitation. Other features of the methods include the use of lithium carbonate as a buffer and rubidium as an internal standard for the potassium determination; and barium carbonate as a buffer and lithium as an internal standard for the sodium determination. The elimination of cyanogen and iron interference with K 4044, K 4047, and R b 4215 lines and the influence of the concentration of one alkali on the determination of the other were discussed. Precision data, obtained from the use of these methods over the past nine months, show the standard deviation for single exposures to be 4 to 5%. E5cacy of Low Inductance A.C. Spark Techniques for Aluminum Alloys. J. T. Rozsa AND L. E. ZEEB,National Spectrographic Laboratories, Inc., Cleveland, Ohio. The feasibility of low inductance techniques with pertinent reference to aluminum alloys was discussed. Correlation of various spark parameters to minimize effect of alloying constituents included size of sparked area, capacitance, electrode form, inductance, number of discharges per half cycle, inert atmospheres, and peak voltage. Routine Spectrographic Analysis of Impurities in Electrolytic Copper. RAYE. WRIGHT, Utah Copper Division, Kennecott Copper Corp., Garfield, Utah. A spectrographic method was described for the analysis of electrolytically refined copper for routine control. Nickel, bismuth, lead, tin, iron, antimony, tellurium, arsenic, and silver can be determined, on a portion of the wire prepared for conductivity studies, in approximately 20 minutes per sample. The method employs a modified globule technique with a multisource d.c. arc. Excellent reproducibility is obtained. Routine Spectrographic Analysis of Impurities in Anode Copper. RAYE. WRIGHT,Utah Copper Division, Kennecott Copper Corp., Garfield, Utah.
The production control quantometer has been applied to the analysis of a variety of slags which are used in steel making. The rapidity and accuracy of analysis are such that positive control of operations through slag analysis can be maintained. By appropriate built-in switching, slag analysis can be incorporated in the same instrument used for pig iron and steel analysis.
A spectrographic method has been developed for the rapid, accurate routine analysis of anode copper, for arsenic, antimony, bismuth, lead, tellurium, nickel, and iron. The method, based on the analysis of a briquetted sample with a modified multisource spark discharge, covers the ranges of concentrations normally encountered in copper anodes used in the electrolytic refinery. The accuracy achieved compares favorably with that obtained by routine chemical methods.'
Effect of Entrance Optics of the Direct Reading Spectrometer upon the Analysis of Stainless Steels. J. J. JURM.4IN, G. ~TRIGHT, AND S. H. WALTERS, Baird Associates, Inc., Cambridge, Mass.
Conversion of an ARL High-Voltage Spark Source to Air-Interrupted Operation. FRED HOLZER, James H. Herron Co., Cleveland, Ohio.
Several methods of grating illumination in a spectrometer have been studied. A comparison has been made upon the analytical results obtained with stainless steel, using these different methods. Results of the study have been applied successfully to actual control analysis. A simple general theory was presented mith supporting evidence.
An ARL high-voltage spark source, equipped with a synchronous gap, has been converted t o include alternate use of an air interrupter. With the latter, steady operation up to eight condenser discharges per half-cycle is possible, using a 0.007-microfarad capacitance a t full power. With the condensers connected in series, as many as 40 breaks per half-cycle hare been counted. In addition to the air-interrupted spark, a spark-ignited 220-volt ax. arc section has been added, and existing instrumentation expanded to include oscilloscope, R. F., and a.c. current meters. The result is a compact, self-contained unit of considerable versatility, obtained at a cost appreciably below that of similar spectrographic sources available commercially.
Spectrochemical Determination of Minor Constituents of Stainless Steel. CHARLES H. CORLISSAND BOURDOX F. SCRIBNER, National Bureau of Standards, Washington, D. C. The spectrochemical detection and determination, by direct excitation of the metal sample, of 16 minor constituents in 18 chrome8 nickel stainless steel were studied to determine optimum conditions for analysis. The elements investigated were Al, As, B, Co, Cu, Mo, Nb, P b , Si, Sn, Ta, Ti, V, W, Zn, and Zr. The high-voltage condensed spark employed for determining major elements serves for several of the minor elements such as Co, Cu, Mo, Nb, Si, and V in concentration ranges commonly encountered in commercial samples. For low concentrations of elements the a.c. arc provides for nearly all determinations, although the determination of Ta is insensitive. Boron is readily determined by the a.c. arc on rod samples to a concentration of 0.0005%. A Multisource discharge suggested by Hasler for determining T a has been found very satisfactory for this element and for Nb as well. Line pairs, detectabilities, and interferences are given for the elements studied. Spectrographic Determination of Sodium and Potassium in Coal
Design and Performance of the Perkin-Elmer Model 99 Double Pass Monochromator. C. D. COX-LES, Perkin-Elmer Corp., Norwalk, Conn. The met,hod of Walsh [.Vatwe, 167, 810 (1951)], for converting a conventional Littrow-type single-pass monochromator to double monochromator operation by using the prism for four refractions instead of two, has been applied to the Perkin-Elmer Model 83 Universal monochromator. For modulated beam operation the new principle yields double monochromator performance with the optical and mechanical simplicity of a single monochromator. The dispersion is doubled and the radiant power per spectral slit width is twice that of the single pass monochromator multiplied by the efficiency of the second radiation traversal. F a k radiation is reduced appreciably-e.g., from
ANALYTICAL CHEMISTRY
604 10% at 15 microns to less than 0.1%. The modification is such that it can be applied to existing single pass monochromators.
Improvements in Baird Associates Infrared Spectrometer.
W. A.
PATTERSON, Baird Associates, Inc., Cambridge, Mass. Modifications to the Baird Associates infrared spectrometer have greatly improved its performance and utility. Typical performance data were presented, new accessories described, and proposed developments discussed. Analytical Applications of the Raman Quantometer. M . F. HASLER,J. W. KEMP,AND G. ANDERMANN, Applied Research Laboratories, Glendale, Calif. With the availability of a highly precise direct-reading instrument suitable for the measurement of Raman spectra, current analytical practices can be readily studied and refined. Such studies have demonstrated means of enhancing accuracy and detectability in the measurement of components of a mixture. The pioneering work of Heigl, Black, and Dudenbostel [AXAL.CHEM., 21,554 (1949) ] on the determination of the total olefin content of a mixture of hydrocarbons has been repeated and extended. Rotation-Vibration Spectra of Allene and Allene-dd. R. C. LORD P. VENKATESWARLU, Massachusetts InstitUte Of Technology, Spectroscopy Laboratory, Cambridge, Mass. AND
The infrared spectra of allene and allene-da vapor have been measured with a prism instrument over the spectral range 250 to 4000 cm.-l The data so obtained, together with the Raman spectra of liquid allene and allene-dr, lead to a complete vibrational analysis that satisfies the product rule for the various vibrational species. The torsional vibration is ascribed t o a weak line in the Raman spectrum of allene at 865 cm.-1 and a very weak line in allenedr at 615 cm.-1 The former figure agrees satisfactorily with a value of 812 suggested by Linnett and Xvery on the basis of heat-capacity measurements. Approximate zeta-values for certain of the perpendicular bands have been determined, and with their help the moment of inertia about the figure axis was evaluated. The result leads to a value for the HCH angle of 114.5’ if a C-H distance of 1.07 A. is assumed. Infrared Spectral Differentiation between Paraffinic, Cyclopentyl, and Cyclohexyl Structural Groups. S. A. FRANCIS, The Texas Co., Beacon, X. Y.
.4 study of the prism and grating spectra of pure hydrocarbons obtained from the American Petroleum Institute Research Projects 42 and 44 has shown the following correlations between infrareg spectra and molecular structure: (1) CHa groups and CHZgroups in cyclopentyl rings produce absorption maxima near 3.38 and 3.48 microns; (2) paraffinic and cyclohexyl CHZgroups produce absorption maxima near 3.42 and 3.50 microns: (3) absorption maxima are produced near 6.82 microns by paraffinic CHz groups, near 6.87 microns by cyclopentyl CHZgroups, and near 6.90 microns by cyclohexyl CH2 groups: ( 4 ) cyclohexyl groups produce an appreciably stronger 11.2 microns absorption than either paraffinic or cyclopentyl groups. A type analysis for paraffinic, cyclopentyl, and cyclohexyl structural groups in saturated hydrocarbons has been worked out and applied to a large number of pure hydrocarbons obtained from American Petroleum Institute Research Projects 42 and 44. The method is based upon absorbance measurements from the grating spectra at 6.820, 6 855, and 6.900 microns. The method is capable of detecting one cyclohexyl ring in 40 carbon atoms, but appears somewhat less reliable for paraffinic and cyclopentyl groups. When applied to six A.P.I. Research Project 6 samples from the lubricating oil fraction of an Oklahoma crude, the method indicated that the cycloparaffin rings were primarily cyclopentyl rather than cyclohexyl.
report is of a somewhat detailed study of these limitations and methods to minimize them. Investigation showed that single wave lengths in the characteristic bands would suffice reasonably well for all groups except the RR’C= CHR” type. For this one foui wave lengths in the 12.0 to 12.5 micron region were used and over-all averages were used both in the calibration and sample data. The elimination of nonolehic component background was achieved by the use of a careful chromatographic fractionation in a researchtype column. Depending upon the sample, between 70 and 120 cuts are taken and their refractive indexes determined. A plot of refractive index versus cut number then distinguishes the olefin range. Cuts from this range are then recombined and analyzed for the individual olefin types. These results are then combined either with a bromine number determination or a total olefin content determined from the chromatogram to give a complete analysis. Results for synthetic blends containing several members of all types and results for representative gasolines were discussed. More about Olefin Group Correlations in the Infrared. JAMES D. STROWPE, Research Laboratories, Rohm & Haas Co., Philadelphia, Pa.
If at least one methylene group “insulates” the double bond from polar substitution or conjugation effects, it is generally safe to apply the useful correlations between the low frequencies of certain hydrogen-wagging motions of mono-olefinic hydrocarbons and their respective cis, trans, vinyl, and R(R’)C=CHCR”) structure types. Direct polar substitution or conjugation effects generally cause marked shifts in the olefin-type hydrogen-wagging frequencies. For some special classes of polar olefins these shifts are sufficiently consistent to establish subcorrelations helpful in proof of structure work. Geochemistry of the Stable Carbon Isotopes. H. B. CRAIG,University of Chicago Institute for Nuclear Studies, Chicago, Ill. Some 300 samples of carbon from various geologic sources have been analyzed in a new survey of the variation of the ratio C13/CIz in nature. Mass spectrometric determinations were made on the instruments developed by H. C. Urey and his coworkers utilizing two complete feed systems with magnetic switching to determine small differences in isotope ratios between samples and a standard gas. With this procedure variations of the ratio Cl3/C12 can be determined with an accuracy of * O . O l % of the ratio. The results confirm previous work with a few exceptions. The range of variation in the ratio is 4.57,. Terrestrial organic carbon and carbonate rocks constitute two well defined groups, the carbonates being richer in C13 by some 2%. Marine organic carbon lies in a range intermediate between these groups. Atmospheric carbon dioxide is much richer in C 13 than was formerly believed. Samples of graphite, diamonds, and igneous rocks as well as gas samples from Yellowstone Park have been analyzed. Fossil wood samples dated by C14 determination and a series of samples from a 3000-year-old Sequoia have been analyzed and show no correlation of C13/C12 with age. If petroleum is of marine organic origin, a considerable change in C’3/Cl2 ratio has occurred. Such a change is sho-xn to have occurred in carbon from black shales and schists of sedimentary origin.
Olefin Group Type Analysis by Infrared Absorption. ELEANOR L. SAIER,ABBOTTPOZEFSKY, AND NORMAN D. COGOESHALL, Gulf Research & Development Co., Pittsburgh, Pa.
Variations of 0 1 8 / 0 1 8 Ratios in Calcium Carbonate of Marine Shells and Their Implications. S. EPSTEINAND H. A. LOWENSTON, University of Chicago Institute for Nuclear Studies, Chicago, Ill. Development of a mass spectrometer for measuring variations of 01*/01@ ratios to an accuracy of * O . O l % permitted the determination of a method for measuring temperatures at which marine animals lay down their shells. Studies of shell growth temperatures of marine animals of the present, post-Pleistocene, and Pleistocene from Bermuda, where the present temperatures of the water vary over a range of 18’ to 28’ C., show that the same species grow at the same temperature range during this period of time but that the growth-temperature ranges are different for different species of animals. It appears that the seasonal variations of post-Pleistocene and Pleistocene temperature of Bermuda water were similar to the one of the present. The processes of burial and fossilization without mineralogical changes do not seem to affect the isotope composition of the calcium carbonate and hence the temperature thermometer.
With the exception of the completely substituted type, there are characteristic absorption bands for each of the aliphatic mono-olefin types. The infrared analysis for olefin types by the methods applicable to multicomponent analysis for individual components suffers from three difficulties: the correct evaluation of the cell attenuation factor; the variation of extinction coefficient and wave length of maximum absorption for the characteristic band for members of the same group of olefins; and the correct evaluation of background absorption due to the nonolefinic component of thesample. The present
Mass Spectrometer Study of Silicon Tetrafluoride. ROBERTE. RUMMEL (now at Vanderbilt University), JOHNR. SITES,. 4 ~ nRUSSELL BALDOCK, Oak Ridge National Laboratory, Oak Ridge, Tenn. Silicon tetrafluoride was analyzed in a sector-type mass speotrometer, and the cracking pattern determined, along with appearance potential curves. Also a metal tetrafluoride was run at high temperatures and a very intense silicon tetrafluoride pattern with several metastable masses was found.
V O L U M E 2 4 , NO. 3, M A R C H 1 9 5 2 Mass Spectrometer Investigation of UFa. L. 0. GILPATRICK, RUSSELLBALDOCK, AND JOHNR. SITES, Oak Ridge National Laboratory, Oak Ridge, Tenn. I t was found from thermal dissociation studies that UFa dissociates at all temperatures from 700’ C. upward. The rate of dissociation increases steadily with rising temperature to yield UF, and uranium metal. I i o evidence of the sublimation of unaltered UFa could be fovnd with temperature in the range of 750’ to 1000° C. Mass spectrometer data were presented to support these conclusions. Mass Spectrometer Study bf Teqhnetium. RUSSELLBALDOCK, JOHN R. SITES,AXD L. 0. GILPATRICK, Oak Ridge National Laboratory, Oak Ridge, Tenn. A sample of approximately 5 mg. of solid ammonium pertechnetate was examined in a mass spectrometer to set the best possible upper limit to the existence of isotopes of masses 97, 100, and 101. Fission product residues mere the source of the nearly pure technetium salts. Upper limits were set with respect to Tc 99 as follows: Tc 97, 1/2000; Tc 100, 1/5000; and Tc 101, 1/5000. Incidental to this study several interesting observations were made of the types of ion formation peculiar to technetium compounds as well as on large number of valence states. AND Needle-Valve Type of Variable Gas Leak. E. F. BABELAY L. A. SMITH,Carbide and Carbon Chemicals Co., Oak Ridge, Tenn. A high vacuum needle valve may be used as an adjustable leak for admitting gas samples to a mass spectrometer and regulating their flow rate, if the valve is provided with a wedge and lever system providing very sensitive control of the needle position. Flow through the leak is molecular at spectrometer pressures, but mass flow may be secured by arrangement of the tubing between the sample and the leak. The leak may be closed completely, thereby simplifying the design of sample inlet systems.
Automatic Lever Controller and Distributing Mechanism for Liquid Nitrogen. P. ROCHLIN, R . M. GUTTER, AND J. V. R. KAUFMAN, Ordnance Corps, Picatinny Arsenal, Dover, N. J. A distributing mechanism and control circuit for automatically filling the three traps of a General Electric analytical mass spectrometer from a single liquid nitrogen storage container were described. The apparatus is arranged so that each trap can be filled separately or in combination. Control of the liquid level is based on the resistance change of copper wire-wound resistors immersed in the traps. At a certain optimum value of resistance a WE 275A relay is energized. “Airpressure” and “venting” solenoid valves are simultaneously operated and liquid nitrogen is forced through the distributing mechanism into the trap or traps. Additional valves may be installed if it is desired t o control additional traps. Combined X-Rag Absorption and Diffraction Technique for Quartz Analysis. JEANLEROUXAND DON LENNOX,Industrial Health Laboratory, Department of National Health and Welfare, Ottawa, Canada. Routine quantitative analysis for quartz by x-ray diffraction in the silicosis problem poses the double problem of speed and accuracy. The direct-reading technique in which the intensity of a strong quartz line in the unknown powder is compared with its intensity in a pure quartz sample is rapid but susceptible to large errors due t o variations in x-ray absorption and density of the materials associated with quartz. The “internal standard” technique consists of mixing the unknown and a suitable powder known as the internal standard in definite proportions and comparing intensities of a strong quartz line and a strong line of the internal standard. Reasonable accuracy is attained but sample preparation is time-consuming. The method suggested in this paper combines the advantages of the previous two. The quartz concentration in an unknown is determined graphically after measurements of the diffracted intensities of the main quartz line and the transmitted intensities are measured and compared with those for a pure quartz sample. X-Ray Diffraction Method for the Analysis of Bauxite Exploration Samples. R. H. BLACK,Aluminium Laboratories, Ltd., Arvida, Quebec, Canada. The Korth American Philips x-ray spectrometer has been applied to the rapid quantitative analysis of bauxite samples. The minerals gibbsite, boehmite, kaolinite, and quartz, as well as the total iron minerals, are determined: the equivalent values for H20, SiOl, FenOs, and &Os are calculated therefrom. The diffracted intensities are recorded on a paper tape by an automatic counter. The proportions of the various minerals are obtained from calibration charts
605 based on chemically analyzed samples: subsequent calculations and final listing are done by IBM equipment. The time required per sample is about 12 man-minutes, which is much less than that required.by wet chemical methods. The accuracy of the method is sufficient for many purposes, and specific data were presented. X-Ray Diffraction Method for Determining the Origin of Industrial Dusts. LAWRENCE L. SCHMELER, California Department :of Public Health, Bureau of Adult Health, Berkeley, Calif.
A method was presented for the rapid and precise comparison of powder diffraction patterns. This comparison is made possible by recording a number of diffraction patterns on a single strip chart which is produced by an automatic recording x-ray spectrometer. The instrumental modifications required to permit the placing of these patterns in juxtaposition on the chart were shown. The application of this method to the determination of the origin of industrial dusts and the subsequent solution of atmospheric dust problems were discussed. This discussion included the technique of sample collection, sample preparation, instrumentation, and methods of recording and interpreting data. Two examples of the use of the method were discussed, showing the type and specificity of results that can be expected, Analysis of High Temperature Alloys by X-Ray Fluorescence. R. M. BRISSEY,Thomson Laboratory, General Electric Co., Lynn, Mass. Routine determinations of chromium, cobalt, iron, molybdenum, and nickel in a high temperature alloy are being made by x-ray fluorescence at this laboratory. The method is also applied to experimental modifications of this alloy type. Standards having x-ray absorption properties similar to the samples for analysis are used. Mass absorption data are used as a qualitative guide in determining allowable composition differences between standard and sample. Data pertaining to the following were discussed: homogeneity of the alloy, precision of the method, influence of metallurgical processing, and comparison of values obtained by chemical and fluorescent methods. Quantitative Analysis with the Fluorescent X-Ray Spectrograph. HOWARD F. CARLAND WILLIAM J. CAMPBELL, Bureau of Mines, College Park, Md. The fluorescent x-ray spectrograph has been proved to be a useful analytical instrument particularly for certain quantitative analyses very difficult by more conventional methods. The nondestructive analysis of titanium alloys is quickly and accurately made over a wide range of concentrations, as is the determination of hafnium and zirconium in this alloy system over the entire range of concentrations above about 0.01%. Likewise the determination of the niobium and tantalum content of their ores is facilitated, and the accuracy of such analyses is greatly increased by the use of this type of spectrograph. The determination of uranium and thorium in those minerals in which both occur is also being studied. The technique and applications of this method of analysis, its limitations, and reliability were discussed. Spectrophotometric Adaptation of the Zirconium-Alizarin Sulf onate Method for Fluorides. E. A. ARNOLD AND M. A. L ~ V I T I N , Caselnstitute of Technology, Cleveland, Ohio. The usual method for determining fluorine using the zirconium complex with sodium alizarin sulfonate has been adapted to a spectrophotometric procedure. Since the fluoride ion displaces the dye in the zirconium lake, thus returning the dye to solution, two colors exist in solution a t the time the comparison is made-namely, the reddish color of the excess zirconium lake and the yellow color of the released sodium alizarin sulfonate. By studying the wave length versus transmittance curves for these two components separately, it was found that a t a wave length of 420 mp the sodium alizarin sulfonate may be suitably measured, while at 520 mp the zirconium lake may be suitably measured. Since, in a solution containing fluoride ions, both coloring agents are present in a ratio dependent on the amount of fluoride ion, the transmittances a t these two wave lengths are related to the fluoride concentration. By constructing a nomographic chart consisting of three equidistant and parallel straight lines, the instrument can be calibrated t o determine fluorides. The transmittances at 420 and 520 mp are plotted on the two outside lines and the fluoride ion on the central line. By laying a straight-edge across the nomograph connecting the above two observed transmittances, the fluoride concentration can be read from the central line. This method has the advantage of eliminating personal errors accompanying any method dependent upon a visual matching of colors,
606 Once a calibration is obtained, it will not be necessary to prepare a set of standards every time a fluoride determination is run, as is the case when the comparison is made by visual matching. Spectrophotometric Method for the Determination of Fluorides.
H. E. BUMSTED AND J. C. KELLS, Indiana State Board of Health,
ANALYTICAL CHEMISTRY p.p.m. of titanium when I-cm. absorption cells were used. The exact adjustment of pH is not critical, although the control of pH within certain limits is necessary. The effect of various diverse ions has been studied. The general procedure was tested by analyzing several standard samples and was found to give satisfactory results.
Division of Industrial Hygiene, Indianapolis, Ind. A method was presented for the determination of fluoride ion using a modification of the zirconium alizarin reagent. This method permits the use of spectrophotometric measurement of the degree of bleaching of the alizarin zirconium lake by the fluoride ion rather than the usual titration or visual color comparison. This method has been used extensively (by this group) in the determination of fluoride ion in urines and atmospheric samples. The sensitivity ranges from 5 to 200 micrograms of fluoride per ml. Ultraviolet Spectrophotometric Determination of Cobalt. G. TELEPAND D. F. BOLTZ,Department of Chemistry, Wayne University, Detroit, Mich. An ultraviolet spectrophotometric method for the determination of cobalt has been developed. A green complex is obtained when cobalt(I1) is treated with hydrogen peroxide and a saturated sodium bicarbonate solution. The absorbancy maximum is at 260 mp. Conformity to Beer's law was found for 0 to 8 p.p.m. of cobalt using I-cm. absorption cells. The effect of diverse ions and the optimum conditions for the development of the complex were studied. The main interferences are ferric, molybdate, titanic, uranyl, vanadate, and ferrocyanide ions. The procedure as developed is rapid, accurate, and convenient and should be applicable to a variety of samples. Spectrophotometric Determination of Iron a s Ferric Sulfate Complex, Ultraviolet Study. ROBERTBASTIAN, RICHARDWEBERLISG, A N D FRAXK PALILLA, Sylvania Electric Products, Inc., Kew Gardens.
N. Y. The absorption spectra of ferric perchlorate and ferric sulfate solutions were examined for use in the determination of iron. I n the near ultraviolet region the absorption of a dilute ferric perchlorate solution can be reduced almost to zero by adding excess perchloric acid. When sulfuric acid is added t o such a solution, the absorbancy increases sharply, owling to ferric sulfate complex formation. The procedure produces a system which is insensitive to the acidity originally present and adheres very well to the normal absorption law. The interference of many metals is small and can be minimized by use of a portion of the original solution as a blank. A variety of standard samples containing 0.04 to 1.5% iron were analyzed. Spectrophotometric Method for Following Dichromate Oxidations.
M. J. CARDONE ASD J. IT. COMPTON. Research and Development Division, Wyandotte Chemicals Corp., Wyandotte, Mich.
A method has been developed which enables the course of dichromate oxidations to be followed spectrophozometrically. Previous workers who have attempted to follow such reactions photometrically have been hampered by the effect of low sulfuric acid concentrations upon dichromate absorption. This effect, which is more serious in the ultraviolet, has been overcome by the addition of phosphoric acid as a stabilizing agent. The absorption measurements are made a t the dichromate maximum a t 349 mp. At this wave length chromic ion does not absorb. Background readings are made a t 850 mp. In a 5 M phosphoric acid solution Beer's law is obeyed for potassium dichromate concentrations in the range of 0.15 to 0.30 milliequivalent per 100 ml. These solutions may be up to 0.90 ;I1 in sulfuric acid. The method is independent of normal slit width variations and the solutions are optically stable for a t least 3 hours. For ordinary work sulfuric acid concentrations below 0.45 'iA can be ignored and an average absorption factor as experimentally determined may be applied with an accuracy of &0.6% of the potassium dichromate present. When maximum accuracy is required or for sulfuric acid concentrations between 0.45 and 0.90 M an accuracy of *0.3% is realizable by obtaining the k absorption constant from plots of optical density vs. k at several sulfuric acid concentrations. Interference studies have been made and the method successfully applied to several classes of organic compounds. Comparison of results obtained by the spectrophotometric method with the usual iodometric method showed excellent agreement. Spectrophotometric Determination of Titanium. EDWARD HINES D. F. BOLTZ,Wayne University, Department of Chemistry. Detroit, hfich. AND
A new spectrophotometric method for determining small amounts of titanium has been developed. Titanic ions react with an excess of ascorbic acid to give a yellow complex exhibiting maximum absorbancy a t 360 mp. Conformity to Beer's law was found for 0 to 25
Nephelometric Determination of Nitrogen Dioxide and Nitrite. W. H. HILL . ~ N DT. F. HATCH,University of Pittsburgh, Graduate School of Public Health, Pittsburgh, Pa. Trace quantities of NO2 or' nitrite have been determined so far largely by colorimetric methods. The colors produced are somewhat fugitive and readings must therefore be made within a definite time interval after mixing of the reagents. This fact prevents the use of dynamic sampling methods. A new method has been developed for the determination of NO2 or nitrites, which is based on the known reaction between nitrite and sulfamate. Sulfuric acid is produced in this reaction and is determined as barium sulfate, by a nephelometric method. The main objections raised against nephelometric methods in the past have been overcome by the development of stable reference standards. The new method is fast, simple, and direct, and employs no complicated apparatus other than a nephelometer. Absorptiometric Method for Determination of Rutin in Buckwheat Leaf Meal and Other Plant Materials. ARTHURTURNER, JR.,Eastern Regional Research Laboratory, U. S.Department of ilgriculture, Philadelphia, Pa. The present gravimetric method for rutin is slow, and not precise when the rutin concentration is small. In the new method proposed, the extracted rutin is complexed with aluminum chloride, and the absorbance is measured at 416 mp. The reliability was tested by replicate analyses and by determination of rutin added to both rutincontaining buckwheat leaf meal and t o marc. On buckwheat leaf meals, the absorptiometric method generally gave higher rutin contents than the gravimetric method, and the divergence increased a t the lower rutin levels. A few analyses by both methods were made on leaves of tobacco, n-ild cherry, common elder, and Eucalpptus macrorhynca, and on buds of Sopho:a japonica. The absorptiometric method requires fewer operations and only about one tenth the time necessary for the gravimetric method without a sacrifice of accuracy or precision. Analytical Applications of Fluorescent Spectra of Aqueous Solutions of the Rare Earths. V. A. FASSEL, R. H . HEIDEL,AND F. HUKE,Institute for Atomic Research and Department of Chemistry, Iowa State College, Ames, Iowa. The chemical properties of the rare earths are so strikingly similar that mixture of these elements defy analysis by the usual methods of analytical chemistry, except in a few cases (cerium and europium) where changes in valence state may be effected. Consequently, uniqueness in any of the physical properties of individual members of the series is of potential analytical usefulness. ilqueous solutions of several of the rare earths possess characteristic fluorescent spectra whose quantitative analytical applications have thus far not been exploited. I n this paper, the fluorescent spectra of cerium, praseodymium, gadolinium, terbium, samarium, and europium were described and a survey of their possible quantitative analytical applications was presented. A Beckman D U spectrophotometer modified for fluorescence measurements. was used in this study. The excitation radiation was brought into the top of the cuvette racking compartment by a lens-mirror combination, so that the monochromator was used t o disperse the fluorescent light produced by solutions contained in cylindrical cuvettes. The fluorescent radiation detector, a 1P28 photomultiplier phototube, was located in the position normally occupied by the spectrophotometer light source and was incorporated in the circuit in such a way that the Beckman instrument was used in the same manner as in transmittance measurements. Conducting Briquet Technique of Spectrographic Analysis. Analysis of Zirconium Metal a s the Oxide. T, A. FASSEL, A. M. HowARD, A N D D. 0. - ~ N D E R S O N , Institute for Atomic Research and Department of Chemistry, Iowa State College, Ames, Iowa. Recent investigations have shown that controlled, high voltage, interrupted-type discharges can be successfully used as excitation sources for the analysis of nonmetallic substances by exciting these materials in the form of conducting briquets prepared from mixtures of the sample and powdered flake graphite. For metal or alloy systems which can be readily converted to the corresponding oxides by oxidation of fine turnings, this excitation technique provides an alternative approach to the analysis of those systems whose metallur-
V O L U M E 24, NO. 3, M A R C H 1 9 5 2
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gical properties are such that metal self-electrodes cannot be fabricated. Moreover, the preparation of standard samples is greatly simplified. The application of this technique to the determination of titanium, iron, silicon, calcium, magnesium, aluminum, copper, and nickel in zirconium metal was discussed. Uniform volatilization rates for the refractory zirconium oxide matrix and the relatively volatile impurities were achieved through proper choice of source parameters, thus making selected zirconium lines suitable as internal standards. Synthetic zirconium oxide standards were made by chemical procedures, validated by self-sufficient spectrographic methods, and verified by comparison with chemical results when methods for the latter were available. Spectrochemical Analysis of Zirconium Oxide. E . J . SPITZER ~ N D . D . SMITH,Stable Isotope Research and Production Division, Oak Ridge National Laboratory, Y-12 Area, Oak Ridge, Tenn.
D
4 spectrochemical method was presented for the quantitative analysis of zirconium oxide for 22 impurities. Silver chloride is used as a carrier in a carrier distillation type arcing procedure. The general range is 1.0 to 0.00017, on most elements and impurities can be determined by visual comparison to an accuracy of 3 ~ 5 0 %of the element present. Quantitative Spectrochemical Analysis of Rare Earth Mixtures. J. A. NORRISAND C. E. PEPPER, Stable Isotope Research and Production Division, Oak Ridge National Laboratory, Y-12 Area, Oak Ridge, Tenn. A quantitative spectrographic method has been developed for the analysis of the major rare earth constituents in solutions using strontium as an internal standard. The concentration range 1 to 100% is covered. Precision of analysis is evaluated as a standard error of 10% of each rare earth determination based on a 99.5% confidence level. Spectrochemical Analysis of Beryllium in Biological Tissue.
JANUB Y. ELLENBURG (present address, Carbide and Carbon Chemicals Co., Y-12 Plant, Oak Ridge, Tenn.) AND LOUISE. OWEN(present address, General Electric Co., Oak Ridge, Tenn.), Spectroscopy Laboratory, NEPA Project, Oak Ridge, Tenn. The apparent toxicity of beryllium and its compounds has become of concern to industry in recent years. While the presence of beryllium in the lung tissues of diagnostic berylliosis has been established, the clinical significance of this fact must await the determination of the absence or presence of beryllium in the tissues of the general populatlon. To provide analytical service on this problem, the spectroscopy laboratory of the NEPA project developed a spectrochemical procedure which yields a sensitivity of 5 X 10-10 gram of beryllium and accommodates large original samples to achieve very high relative sensitivity of detection. The technique uses a new method of sample dimensioning which calls for the comminution of the tissue in the presence of alcohol in a Waring Blendor with subsequent filtration and drying of the solids. The sample so obtained is put into solution by wet ashing, the iron content is extracted with ether, and the beryllium is coprecipitated with germanium. The ashed precipitate is a direct current arced in a controlled atmosphere of 80% HE-20% Oz by volume. The sensitivity obtained is a result of the special atmosphere excitation, Spectrographic Method for Copper in Beer. JOHNJ. STANSBREY R O ~ ~ L IM. ND D E ~ NResearch , Division, Anheuser-Busch, Inc., St. Louis, RIo. A spectrographic method is given for the determination of copper in beer. Germanium, as the internal standard, is added to 5-ml. samples of beer. The samples containing the internal standard are evaporated to dryness and ashed in the muffle at 550° C. The fluffy ash is mixed with graphite, packed into shallow-cupped graphite electrode$,and excited in a d.c. arc; the spectrum is recorded on S.A. No. 1 film using a 21-foot Jarrel-Ash grating spectrograph. means of a step filter a range of 0.07 t o 3.0 p.p.m. copper in beer 1s determined. This method requires less working time than the colorimetric procedure. AND
Precision of the First Phase of Preparation of Limestone Samples. R. K. LEININGER AND ROBERT F. BLAKELY, Indiana Department of Conservation, Geological Survey, Bloomington, Ind. A previous paper indicated that there are two phases in the preparation of limestone samples as used for the spectrographic method employed. That paper demonstrated that the lack of accuracy of determinations on routine samples was not due to loss of representation in the final phase of preparation. The investigation was extended to the first phase of preparation.
This paper outlined in detail the method used to reduce the particle size and weight of a geologist's field sample. Data on the following types of replicate samples were compared with data on the normal routine sample: fines ordinarily lost; samples taken from a split of crushed material normally discarded; samples taken from a split of pulverized material normally discarded; samples not magnetically separated; size fractions from material normally discarded. At least sixteen samples are represented in each of these studies except the last mentioned. The basis of comparison of precision in the study is the precision for standard samples. This study and that reported in the previous paper provide reason for the conclusion that for a given analysis of sample, there is a minimum initial weight which can be processed by the adopted procedure with assurance of a representative spectrographic sample. The studies indicate that replicate sampling of limestone in the field should be undertaken to determine the necessary accuracy of spectrographic determinations of the major constituents. Precision of Final Preparation of Limestone Samples.
ROBERT
F. BLAKELY . ~ N DR. K. LEININGER, Indiana Department of Conservation, Geological Survey, Bloomington, Ind. Spectrographic determination of major constituents in limestone entails great reduction of sample size. With the technique employed the spectrographic sample weighs about one millionth of a geologist's field sample. The preparation procedure consists of two phases: the first reduces the sample to about one one-hundredth of the original weight; the second results in the sample to be analyzed. This paper dealt with a statistical study of the second phase of preparation. The purpose of the study was the determination of the degree of representation maintained through the second phase of preparation. Methods for sampling and preparation were outlined. Results were presented of statistical analysis of precision for 135 determinations of each of several constituents using 27 standards and also 135 determinations using 20 routine samples. Data on the accuracy of the analytical method employed were given for 27 standards and 19 routine samples. Similar results obtained after analysis of data on triplicate samples taken in the three stages of the second phase of preparation were compared with previous information on precision. From the study of the final phase of preparation, the conclusion was drawn that the decrease in accuracy of the analytical method for routine samples in comparison with that for standards is not due to lack of representation incurred during the final phase of preparation. Determination of Xenon in Krypton. J. ALLEN WHEATAND ROYL. WILLIAMS, Air Reduction Co., Research and Engineering Department, Murray Hill, N. J. Krypton containing 0.1 to 10.0% xenon is sealed in a capillary tube at 4-mm. pressure and excited in the high frequency field of a Hartley oscillator. The light emitted by this excitation is examined by a spectrograph and the ratio Xe 4671.2/Kr 4463.7 or Xe 4624.3/Kr 4463.7 determined. By reference to a working curve prepared by similar determination of these ratios for standard mixtures, the concentration of xenon in krypton is determined. Some limitations and other applications of the method were discussed. Determination of the Mineral Constituents of Rocks by Infrared Spectroscopy. J. R.I. HUNTAND D. S. TURNER, The Carter Oil Co., Tulsa, Okla. The infrared spectra of sedimentary rock minerals are obtained by grinding rocks to a fine powder and examining the powder as a film on a conventional sodium chloride window. The mineral constituents of the rocks are identified by comparing their spectra with the spectra of pure minerals. Quantitative analyses can be made for minerals which have sharp, well-defined absorption bands such as quartz, kaolinite, orthoclase, calcite, and dolomite. Errors in the analysis are caused by nonuniformity of the sample film and scattering of the infrared radiation. The technique has been used in analyzing core materials, well cuttings, and surface samples. Infrared Spectra of Evaporated Films. J. E. TYLER AND S. A. EHRIIARDT, Research Laboratories, Interchemical Corp., N. Y . Films of various organic materials have been prepared by vacuum evaporation onto salt plates. The infrared spectra of these films were compared with mineral oil mulls of the same material. Various interesting features of the technique were discussed.
A Horizontal Cell and Its Application to Kinetic Studies by Infrared AND VINCENT J. COATES, The PerkinSpectroscopy. H. HAUSDORFF Elmer Corp., Norwalk, Conn. Using the automatic cycling feature on the Perkin-Elmer Model 21 double-beam spectrophotometer, it is possible to scan spectral re-
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ANALYTICAL CHEMISTRY
608 I
gions at regular intervals so that all spectra are superimposed on the aame paper. A slow reaction which is occurring in a sample placed in the light beam would, therefore, produce a series of superimposed spectra which show that some absorption bands are increasing, others decreasing, while some will not have changed at all. This set of curves provides useful information as to the reaction occurring in the sample. Recordings at constant wave lengths will then give the reaction rates. Inflection points will indicate double or multiple reactions. Since most reactions, such as polymerizations, involve changes of state (generally from liquid to solid), sealed liquid cells, as well as windows suspended vertically in the sample beam, cannot be used for obvious reasons. This situation led to the design of a simple twoplane mirror unit (horizontal cell) which permits passage of the radiation beam through a window in the horizontal position. Thus, samples in the liquid state can be spread over the window and can be examined until the sample has reached the solid state. Heat can be applied around the window to further the reaction rate and reactions can be studied at different temperature settings or under other influences besides heat. Some of the applications of this unit to such reactions were discussed.
ments have become desirable. A simple and accurate method for determining the resolution of a spectrometer using the interference fringes produced by an empty liquid absorption cell was described. Such a cell constitutes an interferometer of the Fabry-Perot type. Since the reflection near normal incidence from the surfaces of the windows is used, the transmitted fringe intensity depends on the refractive index of the window material which does not vary greatly over the spectral range used. The wave-number interval between succeeding fringes is a constant for a given cell spacing, d. Spacings are chosen to give values of wave-number interval which are beyond the spectral resolution of the spectrometer over part of its range. The frequency at which the spectrometer is just capable of resolving wave-number interval above the noise of the detector is used as a criterion of resolution. Plots of wave-number interval versus wave number and wave length for a given spectrometer for a variety of operating conditions were shown and applications of this method mere discussed.
Quantitative Infrared Analysis of Mixtures of Solids by Suspension in Nonpolar Solvents. MEYERDOLINSKY, Division of Cosmetics, Food and Drug Administration, Washington, D. C. Stable fluid suspensions are obtained by dispersing insoluble solids in nonpolar solvents using aluminum stearate as a suspending agent. The resulting suspensions show many properties of solutions when examined in the infrared spectrophotometer. The curves obtained show well-defined peaks and are reproducible. Measurements indicate that Beer's law is applicable to these suspensions. Examples of the analytical application of infrared spectra obtained from suspensions was described. The advantages of this technique when compared to the use of films or mulls, as well as some possible sources of error, were pointed out. Infrared Spectrophotometric Study of Veratrum Alkaloids. GILLES AND R. A. BURLEY. Ayerst. McKenna and HarriPAPINEAU-COUTURE son, Ltd., Montreal, Canada. A method was described by which infrared spectrophotometry can be used: to follow the purification of the hypotensive fraction of Veratrum viride; to follow the isolation of individual hypotensive alkaloids from concentrated extracts; and to estimate the hypotensive activity of the plant extracts. Infrared Absorption of Ethyl Iodophenyl Undecylate and Some Related Compounds. Dox H. ANDERSON, Color Control Division, Eastman Kodak Co., Rochester, N. Y . Kodachrome slides of molecular models and infrared absorption curves of a series of compounds were shown. The compounds range in composition and structure from a saturated hydrocarbon oil to ethyl iodophenyl undecylate. The measurements presented showed how the infrared absorption can be used t o determine the degree of completeness of a reaction, and how the changes in infrared absorption parallel the changes in molecular structure. Rapid and Accurate Gravimetric Method for Analysis of Synthesis Gas. G. L. BARTEUUERAND A. HAQQERTY, Pittsburgh Consolidation Coal Co., Pittsburgh, Pa. A method was described which should find wide application in the analysis of gas samples associated with synthesis gas manufacture. In place of the usual Orsat equipment-which normally handles only about three samples per man-day-the method described permits analysis of as many as eight or nine samples in the same time period. The method involves: mercury displacement of the sample from a calibrated gas bottle into a flowing stream of oxygen, removal of carbon dioxide prior to entry of the sample into the combustion tube, combustion of CO, H2, and CH4 over a platinum-palladium catalyst held at 600' C . , absorption of the combustion products, obtaining weight increases of the absorption tubes, and calculation of the sample composition. In the event of possible contamination by inert materials (Nz,OZ), a separate methane measurement must be made. This can be done rapidly and conveniently using infrared techniques. Interferometric Method of Determining the Resolution of an Infrared Spectrometer. VINCENTJ. COATESAND H. HAUSDORFF, The Perkin-Elmer Corp., Norwalk, Conn. With the increased number of infrared spectrometers in the field, routine testing and comparison of the performance of these instru-
International Congress on Analytical Chemistry Arrangements have been completed for the International Congress on Analytical Chemistry, t o be held a t Oxford, England, September 4 to 9, under the patronage of the International Union of Pure and Applied Chemistry. Meetings of the board and commissions of Section V,Analytical Chemistry, are planned for September 3 and 10. Three main lectures will be given by C. J. van Nieuwenburg, professor of chemistry, Technical University of Delft, Holland, Ralph H. Muller, Los Alamos Scientific Laboratory, Los Alamos, K.RI., and L. H. Lampitt, chief chemist and director, J. Lyons & Co., Ltd., England. The scientific sessions have been divided into nine sections: microchemical, biological, electrical, optical, radiochemical, organic complexes, reporting of results, adsorption and partition methods, and miscellaneous techniques. Papers will be i s k e d in preprint form before the congress meets, and the proceedings will be published as soon as possible after the congress in a special number of The Analyst. During the congress there will be working demonstrations illustrating new techniques or special applications of older techniques in analytical chemistry, as well as a trade exhibition of apparatus and books. Preliminary information as to those who may attend and the accommodations desired is requested, to be sent not later than March 31 t o R. C. Chirnside, Honorary Secretary, Research Laboratories, General Electric Co., Ltd., Wembley, England.
Purdue Industrial Waste Conference The seventh Purdue Industrial Waste Conference will be held May 7 t o 9 in the Purdue hlemorial Union, Lafayette Ind. A p proximately 50 papers will be presented on subjects dealing with industrial wastes and their treatment.
I National Conference on Weights and Measures. Wardman Park Hotel, Washington, D. C., May 20 to 23 Society for Applied Spectroscopy. 7th annual meeting. New York, N. Y., May 22 and 23 Symposium on Molecular Structure and Spectroscopy. Ohio State University, Columbus, Ohio, June 9 to 13 Fifth Annual Summer Symposium. Michigan State College, East Lansing, Mich., June 20 and 21 International Congress on Analytical Chemistry. Oxford, England, September 4 t o 9 Sixth Annual Symposium on Modern Methods of Analytical Chemistry. Louisiana State University, Baton Rouge, La., February 2 to 6, 1953 I
