International Congress on Analytical Chemistry from natural and synthetic rubbers and quantitative analysis of some physical mixtures of polymers.
HE International C o n g r e s s o n h a l y t i c a l Chemistry, under t h e patronage of t h e International Union of Pure and Applied Chemistry, was held at t h e Cniversity of Oxford, Oxford, England, f h p t e m b e r 4 t o 9. Sir Robert Robinson is president of the Congress, Sir Wallace Akers is vice president, and R. C. Chirnside, Research Laboratories, General Electric Co., L t d . , Wemblcy, England, is honorary secretary. Papers and discussions will be printed in special numbers of t h e Analyst. Three congress lectures were given: “Research in Analytical Instrumentation,” by Ralph H. Muller, Los Alamos Scientific Laboratery, Los Alamos, X. M., “Value and Economic Importance of Chemical Analysis in Industry and Manufacture,” by L. H. Lampitt, J. Lyons & Co., Ltd., London, England, and “Contemporary Assessment of t h e Place of Classical Methods in Chemical Analysis,” by C. J. van Nieuwenburg, University of Delft, Delft, Holland. Abstracts of t,he scientific papers presented are printed here.
Metals in Oils. Their Determination by Spectrographic Methods and the Errors Involved. 8. J. H ~ MJ., NOAR, AND J. G. REYNOLDS.
An account was given of an application of emission spectrography to the routine determination of metals soluble in lubricating oils. The method used for these determinations was compared with three similar published methods, and certain aspects of spectrographic technique were enlarged upon.
Ultraviolet Absorption Spectra of Pyridoxine and Related Compounds. AGKESK. LUNNA N D R . A. MORTON. The absorption spectra of a series of compounds related to pyridoxine have been studied a t different pH values. The results permit the calculation of pK values for two- and three-component systems and for some four-component systems. The investigation illustrates the spectrophotometric analysis of complex systems and, in addition, confirms the recently established structure of codecarboxylase (pyridoxal phosphate). The Use of Protozoa in Analysis. L. PROV.4SOLI.
L. D. HAMILTON, S. H . HUTNER,
AND
Protozoan assays for metabolites mirror and foster progress in cell physiology. Particle-ingesting protozoa, such as the ciliate Tetrahymena and certain chrysomonads, are suggested as potential assay organisms for a wide variety of metabolites in high-molecular combination, notably pteroylglutamic acid and protogen (Tetrahymena) and vitamin BIZ(chrysomonads). Algal flagellates such as Euglena gracilis, while not ingesting particulate food, offer a sensitive assay for free vitamin BIZ; planktonic algal flagellates seem especially promising as ultrasensitive assay organisms for certain free vitamins. Study of the nutrition of the hemoflagellate group of parasitic protozoa is an approach to the chemistry of blood. Herpetomonas (Strigomonas) culicidarum, a parasite of insects, is an assay organism for hematin, and is in use for assaying an unidentified factor having a vitamin BIZ-like distribution in nature. Poor availability of lipide nutrients is a major hindrance to the use of cultures of mammalian cells in analysis. The cholesterol requirements of the parasitic flagellate Trichomonas foetus and of the voracious euglenid flagellate Peranema trichophorum provide means for evaluating solubilizers for lipide nutrients. It is considered that increased knowledge of the nutrition of exacting protozoa will contribute to the eventual use of cultures of leucocytes or other mammalian cells as assay cells. Quantitative Determination of Organic Halides.
G. SALob$oN.
Relationships between the structure of organic halides and their rate of reaction with a number of amines have been established. A system of kinetic analysis by evaluation of reaction velocity curves of organic halides is built up on this experience. I t is based on the fact that the reactivity of a halogenated group with amines is a characteristic property of the group and can therefore he used for its identification. Applications are found in three directions: quantitative determination of monohalides, identification of certain groups in polyhalides, and characterization of complex mixtures. All three applications are possible with low-molecular compounds as well as with macromolecules. I n the latter the repeating unit can correspond either to a monohalide or to a polyhalide. The quantitative kinetic analysis of macromolecular halides cannot be replaced by physical methods, while kinetic analysis of lowmolecular halides is mostly an alternative to more conventional analytical approaches. The content of previous papers was briefly surveyed and results on the following topics were reported: identification of chlorinated rubbers, reactivity of some vinyl polymers, analysis of hydrochlorides
The Stabilityof Metal Chelates in Relation to Their Use in Analysis. HENRYFREISER. The acidic dissociation constants of a number of organic reagents in 50% aqueous dioxan have been determined and the chelate formation constants measured in the same solvent by the Bjerrum-Calvin technique for metals such as Cu, Ni, Co, Zn, Pb, Mg, Cd, La, and CelII. Comparisons of the stability of complexes of diketones with those of 8-hydroxyquinoline or 1,2,3,4-tetrahydro-8-hydroxyquinoline, or o-aminophenol and o-aminobenzenethiol illustrate the influence of aromatic resonance, basicity, and the electronegativity of bonding atoms. The relative stability of chelates of 8-hydroxyquinoline and its 2- and 4-methyl derivatives throws light on the steric hindrance caused by 2-substituents, while comparison of 2-(o-hydroxyphenyl)quinoline and 2-(o-hydroxyphenyl)-isoquinoline further illustrates points of steric hindrance and of ring size. 2-(o-Hydroxyphenyl)-benzoxazole forms chelates with many divalent (but not trivalent) metals, but although the relative stability of many reagents followed the order of the second ionization potential of the metals concerned, complexes of 2-(o-hydroxyphenyl)-benzthiazoline were exceptional. The order of stability of metal complexes of dimethylglyoxime showed no abnormalities and the specific behavior toward nickel must he due to solubility factors. This is confirmed by studies of metal complexes of the corresponding 0methyl ether which present many striking features. Analytical uses of 2-(o-hydroxyphenyl)-benzoxaaole,2-(o-hydroxyphenyl)-benzthiazole, and 2-(o-hydroxyphenyl)-benzimidazole were indicated. Colorimetry of Indicators. J. KING. Measurements have been made of the changes in the color of indicators in solutions as the result of changes in hydrogen ion concentration, the colors being treated as subtractive colors. The most desirable color characteristics have been found to be the following: (a)’ The color should change rapidly with change of pH, particularly a t the point of titrimetric neutrality, ( b ) the changes from color to color should be those that can be memorized readily, and ( c ) the colors should retain their brightness under all conditions: ( b ) and (c) can b e completely satisfied only by ideally characteristic colors, and t h e locus for these in the chromaticity diagram of the C.I.E. system has been defined. These ideals have not yet been approached by any indicators, but many attempts have been made to bring about more, desirable color changes by mixing or “screening” indicators. It has been found that whereas this process does not result in increasing the. color changes, it may move the position of colors in the chromaticity diagram to points where they can be more readily memorized. Fortunately, the eye is able to appreciate changes in color that do not approach these ideals, but the closer the indicator can be brought to. them a t the titrimetric neutral point, the more accurately can this point be judged. Identification by X-Ray Diffraction of Crystalline Inclusions in Glass. H. P. ROOKSBY. An account was given of the use of the x-ray diffraction method for determining the nature of crystalline inclusions in glass. The constitution of “stones” occurring in glass articles provides evidence about origin, so that identification by x-rays is of considerable practical importance. A common source is refractory material from the walls or roof of the melting tank or pot: silicates such as ~OZ found , nephelite, NazO.AI20a.2Si02, or leucite, K z O . A ~ P O S . ~ Sare in lime-soda and potash-lead glasses, and reveal chemical reaction t o , have taken place between refractory and glass. Entirely different compounds are found if the inclusion has arisen from devitrification or from undissolved batch. The investigation of opal glasses by x-rays was also discussed. The. presence of the fluorides of calcium and sodium in one class was established some 26 years ago. More recent examination of opal glasses.
1518
V O L U M E 24, NO. 9, SEPTEMBER 1 9 5 2
1519 Ultraviolet Absorptiometric Determina-
tion of Arsenic as 12-Molybdoarsenic Acid. Coe WADELIN AND M. G. MELLON. The familiar process of liquid-liquid extraction of heteropoly acids from water into certain orgmie solvents has been a p plied principally to 12-molybdophosphoric acid. In this paper were reported the results of a study of the extraction of 12molybdoamenio acid from water into butan-1-ol. Following separztion it is pop sible t o make absorptiometric measure ments of the arsenic a t 370 mp where the molecular extinction coefficient (molar absorptivity) for arsenic is 5100. The optimum aoidity and reagent eonoentration for the extraction have been determmed. The effects of 48 diverse ions were reported along with methods for preventing interference by soluble silica. iron. and mall amounts of orthophosphates. A procedure was desoribed by which arsenic in quantities up to 1 mg. oan be measured,
(Left to Right) 11. C. Chirnside, General Electric Co. (Great B r i t a i n ) , H o n o r a r y S e c r e t a r y of the Meeting- Committee; Sir R o b e r t Robinson, O x f o r d University, C o n c. r e s s President; and Sir Wallace Akers, Imperial C h e m i c a l Industries, Congress Vice President
Square-Wave P o l a r o g r a p h y . G. C. BARKERAND I. L. JENKINS. A method was described for eliminating the undesirable effect of the double-layeyer oapaoity current on the sensitivity of an 8.c. polamgraph. A squ&re-wavevoltage is used in place of the usual containing lead and arsenic shows the opaoifyhg material t o be a lead sinwoidd polarizing voltage, and the amplitude of the 8.c. oomponent arsenate with apatitelike crystal &metwe. of composition 3Pbaoi the cell ourrent is measured shortly before each sudden change in (As04)?.Pb0. If phosphorus is Substituted for arsenio, the opacifying the applied voltwe. Preliminary results suggest that the method is medium is the isomomhous vhosDhiLte. These substanoes are Strucuscful for the detection, a t concentrations down to 2 X 10-' N. of &oh a i mimetite and 'pyromorphite. turally ions that are reversihly reduoed,and t h s t thP senaitivityof the method AND C . PHILLIPS. is not arestly influenced by the presence of large concentrations of Gas C U L Y I Y ~ ~ J. ~ GRIFPITHB, ~ ~ ~ ~ ~ D. ~ JAMES, . Recent work on various gas ohromstographic techniques in the authors' laboratory was desoribed. Examples were given of the separation and analysis of volatile organic mixtures by displaoement chromatography from charcoal columns at 100- C. to an &~curaoy of better than 1%. An account was also given of Some elution analyses by the use of partition oolumns. The separations mostly have been followed by 8 thermal-conductivity cell, but some other devioes were described. These included measurement of flow irnpedanoe, measure. ment of changes in the dieleotrio constant on B portion of the oolumn. and various thermal measurements. The most promising devioe depends on surface-potential changes and is sensitive t b extremely low concentrations of vapor. so that the gas-ehromarogrephic methods can be extended t o relatively nonvolatile materials.
ations of 10-9 M.
trodes
~. Quantitative Inorganic Paper Chromatography. A. L n c o n ~GH. SOXMEREYNS. AND G. WANTIER. .. It is possihle t o &Iterthe aspect of B paper cbrornrtnorarn hu ranrlr. ing on six influenoing factors. The Study of these influences leads t o the definition of conditions for obtaining individual cation or anion chromatographic Spot8 an paper. Enampler of eaoh inHuenoing fsotor were given. together with working details for B new ahromatographio separation of aluminum. titanium. and iron in three individual Spots. This separation hss been quantitatively cheeked on chloride by oolorimetrie measurements of the three eluted elements. The whole procedure needs. 330 minutes and results are aCCUrate t o within +2%. Steels and refraotories hsve been successfully submitted t o thisanalysis.
E. Bisaop. An indicator electrode in a. titrstion solution. stabilized with respect
Determination of the Equivalence Point in Potentiometric Titrations. GUNNAR GRAN.
t o the indicated ion or potential. can be used t o supply the steady reference potential required i n potentiometry, so eliminating the standard half-cell and salt bridge. Nonaqueous solutions are being explored for application t o classes of titration other than mid-base reactions. Glass and antimony "reference indicator'' electrodes give results of high accuracy in argentornetric titrations of halides and thiocyanate in aqueous acid, the eurve~being oompletely superimposable on the standard calomel-salt bridge ourves. After the end paint, antimony plates with silver by displacement and the POtential falls. Platinum in unstablieed solution containing nitrate also gives exeellent results, but of lower sensitivity. An a c c u r a c ~of 0.003% has been attained. The presenoe of chromate, or other redox systems. c m s e s negative errors. In absolute ethanol, srgentometry gives remarkably good results with glass, antimony. and platinum "reference indicator" electrodes, the ourves for the glass electrode being of normal shape, those for antimony being in the form of peaks owing t o plating. and those for platinum giving premonitory peaks just before the end point. Greatly magnified potential jumps and rapid attainment of equilibrium make this technique most ertt.rsctive.
When the potential-volume curve obtained during potentiometric titration8 shows only a small potential change a t the end point, it has been customary t o plot n AE/AV-volume curve and to take the peak of this curve as the equivalence point. I n 1950 the author proposed B method of transforming these curves by a numerical manipulation into straight lines intersecting a t the equivalence point. In this paper another way of transforming titration c u r ~ e sinto straight lines has now been developed. A simple theoretical treatment shows that the mcthod oan be applied t o titrations involving acids and bases. ionic precipitations. formation of eomplmes. and oxidation-reduotion reaotions. T o facilitate the use of the method a table has been compiled giving quantities t o be calculated and plotted against volume of titrant added. These quantities can be evaluated by simple slide rule ealouhtions and, since sttraipht-line relationships hold, end points can be obtained by simple extrapolation. The practice of the method is applicable t o potentiometers ealibrated either in millivolts or in pH units, even when titrations other than acid-alkali reactions are in use.
Replacement of Standard Cell and Salt Bridge by Indicator Elecand Use of Nonaqueous Solutions in Potentiometry Argentometric Titrations in Aqueous and Amphiprotic Media.
Gravimetric Determination of Lead, Silver, and Mercurous Mercury on the Microgram Scale. AAMEDM. EL-BADRY AND CECIL L. WILSON.
Following the procedures described, and using samples containing approximately 10 micrograms of ostion, one may expect t o estimate the elements lead. silver, and meroury (in the mereurOuS form) gravimetrically with an aeouracy of approximately f 1%.
~___ l_l
~
Statistical Aspects of Analytical Determinations.
W. J. Yanmx.
The detection and correction of sources of error in analytical procedures are a. major ooncern of analytical chemists. The efficiency of the searoh for the soumes of analytioal errors can be inoreased by scheduling the order of making the determinations so that the determinations fall into rstiond groupings. Two new types of groupings were presented. These groupings have features t h a t are expected t o
ANALYTICAL CHEMISTRY
1520 make them more useful to imwtigators than groupings previously available.
ties has been given and proficiency in indicating such alterations h&s been established experimentally.
Solubilization Titration. A Rapid Method for Analysis of Binary Mixtures of Organic Liquids. E. C. LUMBAND P. A. Wmson.
DIYIES.
A titrimetric method was described for the rapid analysis of oertain binary liquid mixtures t o whioh alternative methods may not be readily spplioable.
A Fundamental Approach to the Establishment of PH Standards. Room G . BATES. The operational definition of pH is madenecessary b y the diversity of pH me&mrementsin the industry and commerce of the present day, yet it deprives the p H of s large part of its fundamental meaning and 8ome of its usefulness. For the measured p H t o be of greatest value to the ohemist, its dimensions and i t s role in chemical equilibria should be olarified. This problem m u be partly solved by the assignment of pH values t h a t represent a conventional hydrogen-ion activity in the solutions with which the assembly is s t a n d a r d i d . Nevertheless, the measured p R can be expeoted t o lie on this aotivity scale only under the most favorable conditions. I n the establishment of pH standards from measurements of the electromotive force of cells without liauid junctions. the activity coefficients of individual ions must be &tim;rted. The several different reasonable estimates of the activity coefficient furnish a family of pH curves that omverge at eero ionic strength. If the ionic strength of thestandard buffer solution isless than 0.1. anuncertainty of 10.01 unit o m be assigned to the average pH value, and a choice among these eurves is unnecess&n~. ~~~~~
~
Polarographyof the Tetrathionate Ion.
W.F U R N E AND S ~ W. C u m
The tettrathiouate ion is reducible at the dropping-mercury eleotrode. I n a supporting electrolyte of potassium nitrate or in electrolytes buffered a t PH values between 0.93 and 10.0, the polarogram shows the peak of pronounced polarographio maximum a t -0.5 volt against the saturated calomel electrode. This peak can be suppressed by means of gelatin or I,y certain dyes, but quinolino and acridine arc e~peciallysuitable as maximum su~ptessors. For the qumtitative determiuat.ion of tetrathionate, polarogriima are best recorded in 1.0 M solutions of phosphoric aeid.or of t h e ammonium phosphates at pH values between 0.93 and 8.15 and with 0.001% of quinoline. With increasing pH within thia range the diffusion-euwent constant for tetrathionate decreases. I n 1.0 21 ammonium dihydrogen phosphate a t 25.0’ C., i / d ( C m t t s ) , measured in thecustomaryunits, has the value 3.18. The half-wave potential is independent of pH values of the 1.0 -11 phosphate supporting eleotrolyte, but it becomes more negative as the omeelitration of tetrathionate increases. For 2.04 millimolar tetrathionate, E4 = -0.256 volt against t h o saturated calomel electrode. The polarographic waves are symmetrioal about their respoetive half-wave potontids, and tho reduction of tetrathionate at the dropping-mercury electrode is irreversible. In the absence of other oxy acids of sulfur, tetrathionate can be determined polarogr&phically with an acourwy of +l%. Methods are suggested for the determination of tetrathionate in the presence of ditlrionate, trithionate. sulfite. or thiosulfate, but pentathionate interferes.
Gradient Elution Analysis. R. J. P. WILLIAMS. Some limitations of ourrent chromatographic prooedures were discussed and the suggestion was made that gradient elution analysis overoomes a number of them. although it hss certain disadvantages. This suggestion is supported by experimental evidenoe on the resolution of amino acids and peptides in oases where the standard procedures yield unsatisfactory results. The general difficulty of obtaining rapid desorption eauilibrium is introduoed and leads t o the examination of ohromatographie development a t different temperaturez with particular reference to the separation of high polymer fraotions. A gradient elution method w a described in which there is ala0 temperature gradient along the oolumn. This procedure resembles a oontinuous fractional crystallisation with which it was compared. Finally, initial experiments were described using this pmoedure but in which the column has no adsorbent properties and is used only 8 8 a support. 1,lO-Phensnthroline and Mono-, Di-, Tri-, and Tetramethyl-1,lOphenanthrolines as Chelated Copper Complex Cations. W. H. MoCunn~AND G. FREDEREOK Ssnr~n. A study ha6 been made of the copper(1) complex cations formed from 28 mono-, di-, tri-, and tetramethyI-1,lO-phensnthrolines. Determinations have been made of the p H values governing the first formation of the colored eopper(1) chelates and the range of p R throughout which the r e d t i n g complex chtions are stable. The determination of the wave length of maximum absorption for eaoh complex cation has been determined and it has been shown t h a t values o m be oalculated that should result from single and multiple substitutions of methyl groups for any or all the 2- t o 9-position hydrogen atoms in the 1,lO-phenanthrolme molecule. The experimentally determined values for the wave length of m a h u m absorption were in d l instances in agreement with the calculated values. The determination of the molecular extinction coefficients for this series of oopper(1) chelates can in a number of instances be predicted with accuracy, hut in most instanoes can be predicted only sualitatively and not with a precision greater than about 20%. By applying the method of continuous variations, the ratio of the number of organio molecules t o oopper(1) atoms in the complex oations formed has been studied and both man+ and bis-type complexes have been indicated. The mono-complex cuprous oations are formed in acid solutions and are colorless in the visual portion of the spectrum. By this study the instability conatants of the complex cations have been postulated as t o the general order of comparison. At the same time the preferential selection of the substituted 1,lO-phenanthroline most suited t o the 8pectrophotometric determination of copper has been determined. A study has been made of the ultraviolet absorption of acid solutions of two of the orgmio molecules used &s oomplexing agents for oopper(1) and the limitations of the procedure BS applied t o analysis have been indicated. The relationship that exists between the electronic structure of 1.10-phenanthroline and the substitution of alkyl groups for the 2- t o %position hydrogen atoms 88 related t o resultant changes in proper-
Statistical Designinthe Study of Analytical Methods.
G.E.P.Box.
The uses of strttistieal design were discussed in investigations to determine the sensitivity of an analytical method and t o determine the conditions making some quantity (suoh as percentage recovery) a maximum. The uses and advsntages of the factorid design i n an investigation of the first type were illustrated by means of an example. The nature of the accompanying statistical analysis and its value in interpreting the results of the experiment were also indicated. I t was shown lionthe number of observations can be reduced in oertain oireumst.ances by the use of ‘‘partial factorials.” Techniques developed recently for use in the seoond type of investigation were outlined. Geometriosllu, the problem is that of finding the position of the top of a mound where the eoordinstes of the position are the levels of the iaotors and the height of the mound is the quantity t o be muimieed. Experiments are performed in a suitable pattern around the starting point t o determine the direction of greetest dope up the mound. This direction is then followed and the woeess repeated. When the maximum is approached B seeand technique by means of which the summit of the mound is locally explored beoomes neoessaiy
(Left to Right) I. M. Kolthoff, U n i v e r s i t y of Minnesota, Spoke Before a Combined Session of the Congress on “The Aging of Precipitates.” H. V. A. Brisme, Imperial College of S o i e n e e and T e c h n o l o g y , W a s Chairman of the Sesd0n
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V O L U M E 24, NO. 9, S E P T E M B E R 1 9 5 2
152L
I. M .KOLTHOFF.
and the activities of enzymes including catalase, peroxidase, cytochrome oxidase, and tyrosinase were affected. The importance of this in relation to the use of fungi to determine trace metals in complex materials t h a t may contain these intermediates was discussed.
Aging of Crystalline Precipitates.
The term “aging” is used t o denote all those irreversible structural changes t h a t occur in a precipitate after i t has been formed; in this sense, the phenomenon of mere aggregation of primary particles, though analytically very important, is not included. Perfection of primary particles results from recrystallization via the surrounding liquid film; a similar process causes the mutual cementation of t,he primary particles comprising an agglomerate. The growth of larger particles a t the expense of the smaller (Ostwald ripening), presumably owing to the greater solubility of the latter, is the classical example of aging. The solubility of metallic precipitates is so small as to preclude its beiug a factor in aging; in such cases, the recrystallization is attributed t o “local elements” that give rise to electrolytic phenomena. Occasionally, the transformation of a metastable modification into another or into a stable form may be met. With imperfect precipitates im the dry state, aging may occur sometimes a t relatively high temperatures, sometimes (as with silver halides) a t room temperature. Aging is not entirely limited to physical processes; hydrous oxides and hydroxides afford examples of chemical aging through the mutual chemical interaction of primary particles. J R . .T. DUORAnalytical Chemistry of Astatine. -1.H. \V..ITEN. G. HOLLSTEIS, A N D H . P. MOEKEN.
GEEST,
The preparatiou of astatine by bombardment of hismntli oxide by helium ions in the Anisterdam cyclotron was described, and methods for rarrying. separating, and coiinting the 211.4t mere discussed. Determination of Small Quantities of Uranium in Rocks and Minerals by Radioactivation. .L A. SY%LES. The determination of microgram amounts of uranium in mineral& and rocks by neutron irradiation followed by radiochemical separation and measurement of the fission product barium mas described. The method hab been applied t o a number of different types of mineral containing as little as 0.0003% uranium in samples weighing less than 0.5 gram. Results show good agreement with those obtained on larger samples by accepted methods of analysis. The method may be of value where the available sample is smallin bome examples of geological age determination 011 individual minerals separated from parent rocks. The advantage.? of the iiew method over existing techniques were outlined.
Use of Fungi for Determining Trace Metals in Biological Materials. D. J. D. NICHOL.AB. The trace-metal requirements of Aspergillus niger (Mulder strain) and Penicillium glairrum (Keilling strain) have been studied in pure liquid culture. I t was shown that iron, copper, zinc, manganese. and molybdenum werc essential micronutrients, but no evidence was obtained that gallium, vanadium, or cobalt was necessary for the optimum gro~vthof either fungus. Experimental methods have been developed for preparing standards for iron, copper, zinc, manganese, and molybdenum. The addition of graded amounts of one of these metals, from deficiency to sufficiency levels, t o a culture solution containing all the other essential nutrients resulted in increased growth of the test fungi. The growth was assessed visually by taking into account mycelial characters, including the extent and type of sporulation, and quantitatively by determining the dry weight yields of the felts. The pure-culture methods included purification of culture solutions by chemical or ion exchange procedures, and the yreparation of water, glassware, and inocula free from trace metals. A . niger, in particular, has been used as a test organism to determine copper, zinc, manganese, and molybdenum in soils, ash of plants, homogenates of fresh plant tissues, and fruit extracts. To determine the trace metals available t o plants in soils, 0.5 gram of the soil was added to culture solutions having the following pH values: 3 to 4 for copper and zinc; 2 for molybdenum; 7.5 for manganese. .It these pH values maximum differences were usually shown betaeeu normal soils and those deficient ill the particular trace metal. The assay method has confirmed deficiencies of copper. zinc, manganehe, or molybdenum in British soils where crop plants mere deficient in the micronutrienta. Differences between the amount of iron in normal soils and those that give rise to iron deficiency in fruit trees (lime-induced chlorosis) were not detected by this method, although the p H of the culture solutions to which the soils were added was varied between 2 and 7.6. The iron contents of normal and irondeficient leaves were similar, so that the element is immobilized within the plants. The bioassay method is better than chemical procedures for determining copper, zinc, molybdenum, and mangaiiebe in soils because of its greater sensitivity, its higher accuracy a t low concentrations of metal, and the close agreement of the results with crop performance. A study of the derangement of metabolism of A . niger by tracemetal deficiencies has shown that free amino acids, vitamins B? and
B12,
Solvent Extraction of Group IIIB Metal Halides. H. M. IRVING F. J. C . ROSSOPTI. With the aid of the radionuclides 7*Ga, Il‘In, and 204T1, the extraction by ether of gallium bromide and iodide, indium chloride and iodide, thallic iodide, and thallous chloride, bromide, and iodide from the corresponding halogen acids has been studied for a range of acid iiormalities. Liquid counting was used throughout. Although a simple density correction proved adequate with the pure @-emitter thallium, a special procedure had t o be devised for gallium and indium t o correct for variations in the counting rate with changes in the average atomic number of the nuclear species present in solution. The new data supplement existing information on the extraction of metal halides and confirm the prediction that indium iodide can be extracted quantitatively from hydriodic acid of low normality (0.5 to 2.5 :V), where the extraction of gallium iodide is negligible. Potassium bromide, cyanide, or fluoride, citric acid, and disodium hydrogen phosphate in concentrations up t o 0.5 N do not reduae the efficiency of extraction, but chloride ions have a slight effect, the percentage of indium extracted from 1.5 f i f hydrochloric acid made 1.5 1M with respect to potassium iodide falling t o 99.5%. The extraction by ether of ferrous and beryllium iodides from 1.5 .TI hydriodic acid was found t o be essentially zero, so t h a t a simple procedure for the determination of indium in the presence of gallium, iron, and beryllium (among other metals) can be based on the solvent extraction of indium iodide. It is shown that free hydriodic acid can be conveniently replaced by sulfuric acid (1 t o 7 N) containing sufficient potassium iodide t o give a concentration of 1.5 M , and a preliminary spectrographic survey has been made of other elements whose iodides might be extracted by ether under these conditions. AND
Determination of Fluorine by the Lead Chlorofluoride Method in Compounds Containing Halogens, Sulfur, Phosphorus, and Arsenic. R.BELCHER, E. F. CALDAS, A N D S. J. CL4RK. When organic compounds containing bromine, iodine, sulfur, arsenic, and phosphorus besides fluorine are decomposed with sodium or potassium in the nickel bomb, ions are likely to be formed t h a t might interfere with the subsequent precipitation of fluoride as lead chlorofluoride. Bromine and iodine would furnish halide ions, which, i t was thought, might form lead halofluorides more insoluble than the chlorofluoride; the remaining elements after treatment of the bomb leachings with hydrogen peroxide would furnish sulfate, phosphate, arsenate, and arsenite ions, and give insoluble lead salts that would interfere with the gravimetric determination. It was found, however, t h a t the bromofluoride was more soluble than the chlorofluoride, and an iodofluoride could not be precipitated under any condition tried. Accordingly, the original method could be operated without modification in t h e presence of bromide and iodide ions. Lead arsenite did not precipitate under the conditions used, but lead arsenate, phosphate, and sulfate interfered seriously. When a titrimetric finish was used there was no interference, but the original precipitation method required modification. Because of the removal of lead ions from solution by the foreign ions, insufficient were left t o give complete precipitation of lead chlorofluoride. A solution of lead nitrate in place of a saturated solution of lead chloride was used as the precipitant. -4n examination was also made of the lead bromofluoride method, but it offered no advantages. Fractionation of Ozokerites and Separation of Optical Isomers. Two Examples of Applicability of Inclusion Compounds to Analptical Problems. W. YCHLENK, 51%. Crea is k n o ~ i to i form inclusion compounds wit,li a wide variety of straight-chain aliphatic compounds of suitable length, which lie enclosed in cliilnnels of diameter -4.5 A. in the crystal lattice of the adduct. Thiourea gives similar adducts, but the channels are wider (-6 A.) and are capable of selectively including certain branched chain and cylic compounds. This selective behavior is utilized in the fractionation of ozokerites, the complex mixtures of hydrocarbon waxes that occur naturally. Four fractions are obtained, comprising hydrocarbons that, respectively, form adducts with urea only, with hoth urea and thiourea, with thiourea only, and with neither substance. The characteristics of various frartions from -4meriran and Russian ozokerite8 were briefly discussed. A further analytical applicatioii of urea adducts depends on their possessing as does quartz, a screw axis of symmetry. When a racemic, compound forms an adduct, four crystal lat,tices may appear-& (or 1-) compound, right-hand urea lattices and d- (or L) compound. lefthand urea lattices. If, however, a suitable seed is present, the urea
ANALYTICAL CHEMISTRY
1522 crystals will grow predominantly according to, e.g., the right-hand screw pattern, and, as the d- and 2-adducts are not mirror images and differ in physical properties such as solubility, a crop of crystals will form t h a t contains a predominant amount of the adduct of one or other optical isomer of the compound. The other isomer is enriched in the mother liquors. Repetition of the procedure will permit the resolution of a racemic mixture without the use of any optically active partner. This novel procedure, which is not confined t o urea adducts, is illustrated by the resolution of 2-chloro-octane. Complexes Formed by Thorium and Uranyl Ions with Complexones.
M. J. CABELL. The Calvin-Bjerrum method has been used t o study the formation of complexes of thorium and uranyl ions with nitrilotriacetic acid (trilo) and ethylenediaminetetraacetic acid (enta). With thorium the formation of definite stable ionic species is indicated. The uranyl complexes are much less stable, hydrolyze more readily, and the uranium is readily precipitated. The results were discussed in relation t o the stability of the complexonates of uni-, bi-, and trivalent cations. Inorganic Chromatography on Cellulose. Quantitative Determination of Tantalum and Niobium in High- and Low-Grade Complex Minerals and Ores. F. H. BURSTALL AND A. F. WILLIAMS. A new chromatographic method, based on cellulose as adsorbent and ethyl methyl ketone containing hydrofluoric acid as solvent, was described for the quantitative separation of tantalum from niobium and for their determination in minerals, ores, and synthetic materials. From a solution of the sample in hydrofluoric acid containing ammonium fluoride, tantalum is extracted first in a volume of 250 ml. of ethyl methyl ketone saturated with water. The column of cellulose is then washed with ethyl methyl ketone containing 1% v./v. of hydrofluoric acid (40% w./w. aqueous solution of hydrogen fluoride), which arrests the movements of titanium, tin, and zirconium. Niobium is then extracted with the same organic solvent containing 12.5% of hydrofluoric acid. After removal of solvent, the tantalum and niobium are usually determined in the appropriate fractions by ignition t o pentoxides. If phosphate ions are present in the original sample, phosphoric acid is extracted by the solvent used for extraction of niobium, so that the procedure for the final determination of niobium involves a separation of niobium from phosphate ions. Ammonium hydroxide has been successfully used for this purpose. Owing to the large amount of sample that is necessary for the analysis of a low-grade ore, chemical treatment of such samples is made prior t o chromatographic extraction. This treatment involves the separation of the earth acids together with s m d l amounts of other ions by hydrolytic precipitation in acid solutions. The procedures are simple and accurate and have been used for the analysis of a wide range of natural and synthetic materials. Countercurrent Microrotary Extractor a s an Analytical Tool.
R.
SPENCE AND R. J. W.STREETON. A micro form of rotary solvent extractor was described. Quantitative extraction of uranium has been attained with columns from 10 to 15 cm. in length, b t h on a cox?tinuous basis and from samples of 1 or 2 ml.
Electrokinetic Ultrafiltration Analysis of Polysaccharides. New Approach to the Chromatography of Large Molecules. D. L. MOULDAND R. L. M. SYNGE. Much of the difficulty encountered in the chromatographic separation of members of polymeric series is due to the inability of the larger molecules t o enter the porous materials used for chromatography. Electrokinetic ultrafiltration was proposed to circumvent this. A preliminary account was given of experiments with collodion ultrafiltration membranes, where this principle gave useful separations of a series of enzyme-synthesized straight-chain polysaccharides. The data suggest that each membrane excludes molecules exceeding a certain length and that molecules penetrating a membrane undergo simple adsorption on its internal surfaces. Precision Counting of Alpha Particles with Special Reference to Determination of Standard Sources. R. HURSTASD G. R . HALL. Methods of alpha counting were discussed and special reference was made t o the absolute determination of standard sources by the use of alpha proportional counters of known low geometry. Operating details of one such counter were discussed in detail. Gas-Liquid Partition Chromatography. A Technique for the AnalyAND A. J. P. MARTIN. sis of Volatile Materials. A. T. JAMES
The theory of the partition column was extended t o include a compressible mobile phase of a pesmanent gas and a method of determiu-
ing the height equivalent t o a theoretical plate of such a partition column was given. A convenient apparatus making use of a gasliquid partition column for the separation of volatile acids or bases and a n automatic recording buret for their detection and estimation by titration were described. With 4-foot columns having a stationary phase consisting of a mixture of a liquid silicone and stearic acid, all n- and iso-acids from formic t o hendecanoic acid can be separated, and by the use of an 11-foot column all the isomers of valeric acid can be resolved. I n the separation of volatile bases advantage is taken of their different hydrogen-bonding power, so that by the use of hydrogenbonding and nonhydrogen-bonding stationary phases many amines can be separated and the types of amine distinguished. The relationship between chemical structure and chromatographic behavior is discussed on the basis of the nature of the interaction with the stationary phase. Some factors influencing column efficiency were described. Quantitative Assay of Pyrogens by the Febrile Response ili Rabbits. DAVIDM. TENNENT AND WALTHER H. OTT. The amount of bacterial pyrogen in an unknown sample can be quantitatively determined by injecting it into rabbits and measuring the rise in their temperatures. The factors that influence the rabbit's response to pyrogens are normal temperature, body weight, individual sensitivity, excitation, and the tolerance phenomenon. The effect of these on the pyrogen assay can be minimized by a selection process. Rabbits should have normal temperatures between 37.8' and 39.0' C., and should weigh 2 to 4 kg. Their response to a dose of 1 unit of pyrogen standard per kg. should fall between O.liD and 1.6' C., and their response should not exceed 0.3' C. when they are given pyrogenfree water. The effect of tolerance is reduced by a rest schedule. When rabbits are given graded doses of pyrogen the average febrile response in degrees Centigrade is a linear function of the logarithm of the dose. The regression determined for the authors' pyrogen standard is Y = 1.00 0.78X,where Y = average maximum temperature rise in degrees Centigrade and X = log dose per kg. in pyrogen units, one unit being defined as 0.1 mg. of prepared standard. As the numerical values in the equation may change from time to time, the response of the rabbit colony to the standard must be redetermined a t intervals. Routine samples are assayed for pyrogenicity by injecting them into a t least one group of three rabbits whose temperatures are measured twice before and three times at hourly intervals after the injection. The results are calculated by comparing the average of the maximum temperature rises with the standard dose-response relation. Pyrogenic samples are assayed by injecting a series of dilutions of them into several groups of rabbits. The temperature rises are compared with those of similar groups given the standard pyrogen preparation.
+
Use of Ion Exchange Resins for Separation of Nitrogenous and Other Extractives of Plant and Animal Tissue. S. M. PARTRIDGE. A systematic procedure was outlined whereby the water-soluble extractives of plant and animal tissues are separated into groups for identification by paper chromatography or for quantitative estimation. Individual members of the groups are then separated by displacement chromatography on ion exchange resins on a scale large enough to permit the chemical characterization of new or unexpected components. After prior removal of substances of high molecular weight, the extract is passed through a cation exchange column and an anion exchange column connected in series. The neutral substances pass through the assembly unabsorbed and the organic bases and organic acids can be recovered in a salt-free condition by development of the columns. Fractionation of the group consisting of the organic bases and amino acids by displacement chromatography with a variety of resins has been studicd in detail, and the results of a moricl experiment were described in which sixteen amino acids were isolated in a crystalline condition from the hydrolysis products of a protein. Recent Advances in Infrared Spectroscopic Techniques with Reference to Analytical Applications. N. SHEPPARD. An account was given of some recent advances in the design of infrared spectrometers that seem likely to be incorporated in the future in instruments designed for analytical work. Particular emphasis was given to the use of double or multiple monochromaton and echcllette diffract,ion gratings for the improvement of the dispersion of conventional instruments. Trends in the design of multislit, double-beam, and fast-scanning spectrometers were discussed, and the properties of the available detectors of infrared radiation were indicated in relation t o these various applications. Some recent developments in microspectroscopy and high- and low-temperature infrared spectroscopy were briefly enumerated. and some effects of the change of state on the infrared spectrum were meiitioned.
V O L U M E 2 4 , NO. 9, S E P T E M B E R 1 9 5 2 Some Factors Controlling the Selectivity of Organic Reagents. H . A N D R. J. P. WILLIAMS. M. IRVING
The formation of a complex, ML,, from a cation, M , and an acidic reagent, H L , was discussed in terms of the stability constants, kn = (ML,]/ [MLn-l] [L],governing equilibria between intermediate species M L , MLz, . . . . ML,-I present in solution, and cases corresponding to normal behavior, steric hindrance, and orbital stabilization were considered in relation to analytical determinations involving absorptiometry, precipitation, and the solvent extraction of complexes. Sensitivity tests for the preliminary investigation of new reagents were discussed, and correlations noted between the stability of metal complexes and their intrinsic solubility, the nature of the metal, the nature and acid dissociation constant of the reagent, and the pH of precipitation or extraction. Irrespective of the nature of the ligand, a definite order Mn < Fe < Co < Ni < Cu > Zn holds for the stabilities of bivalent transition metal complexes (but not for other valencies or elements), so that some mutual interference of these elements is inevitable in tests with ordinary ”selective” reagents. A class of more specific reagents was discussed, for which the name “singular” was proposed. Examples were given of singular reagents that induce absorption bands of an unusual character that may be analytically useful, and the singular properties of 2,2’-dipyridyl and its derivatives as reagents for ferrous iron were emphasized. Reagents so constructed that the ferroin reaction is inhibited by reason of steric hindrance mere quoted as singular reagents for cuprous copper, and a theoretical explanation of the highly specific character of reagents such as “neocuproin” was proposed. New reagents containing the cinnoline (2-azaquinoline) ring were cited as more sensitive reagents for iron and copper than any hitherto described. Neutron Activation Analysis. Determination of Trace Quantities of the Alkali Metals. M. T. KELLEY, G. W. LEDDICOTTE, AND S. A. REYNOLDS. Nuclear science has created a new analytical procedure for the determination of trace quantities of many elements. This procedure, activation analysis, is a method in which nuclear reactions in a chainreacting pile (or an accelerator) produce an artificially radioactive isotope of the element to be determined. This radioisotope has its own characteristic radiations and mode of decay. Activation analysis is unique because (1) it has great sensitivity of detection for most elements, ( 2 ) other elements do not interfere because each radioisotope has its own decay constant and type of radiation, and (3) contamination as experienced in most conventional methods is negligible unless present before activation. The nuclear reactions that take place in the Oak Ridge National Laboratories, graphite reactor now form the core of an analytical service for the determination of trace elements in many different materials, This paper discussed the techniques of the method, its sensitivities, and applications. Special attention was directed to the determination of trace amounts of the alkali metals by neutron activation analysis. Direct Microdetermination of Oxygen in Organic Substances. JOSEF USTERZAUCHER. A historical survey of the development of the direct microdetermination of oxygen in organic substances on the principle of a reduction with carbon, together with a list of the literature that has been published on this subject, was followed by a detailed description of the micromethod developed by the author in 1940, consideration being given to long years of experience in daily operation. The method consists of the thermal decomposition of the substance in nitrogen that is free from oxygen, conversion of the oxygen into carbon monoxide wit>hthe aid of carbon a t 1 1 2 0 O C., and determination of the cttrbon monoxide by iodine titration: 1 mg. of oxygen corresponds to 7.50 ml. of 0.02 N sodium thiosulfate. The standard sample weight for the determination of the constitutional oxygen is 3 to 5 mg., the accuracy is *0.2% absolute. Satisfactory results are still obtained wit,h sample quantities down t o 0.3 mg. Sample weights of 20 nig. and more are used for the determination of small quantities (traces) of oxygen. The accuracy is then approximately 270 relativc. An oxygen determination carried out as one of a series lasts approximately 30 minutes. The method works without any blank values-i.e., without the subtraction of a blank value from the result. The apparatus and the functions of the individual parts were described in detail: the carrying out of an analysis and the operation and supervision of the apparatus for practical use were also described comprehensively. The materials and reagents used, such as quartz tube, nitrogen, copper, carbon, and anhydroiodic acid, were dealt with in particular detail with reference t o their preparation and their
1523 purification with a view to a working method that is free of blank values. The range and the limits of the application of this method were given. Statistical Methods in Radiochemistry. L. MARTIN. The author emphasized the interest of the design of experiment and the statistical analysis of experimental results. He pointed out the methodological difference between a model or scientific (in this instance, radiochemical) hypothesis and a statistical hypothesis. Mention was made of two applications by C. I. Bliss of statistical analysis to radiobiological data. From data on irradiation of methylene blue solutions in aerated water at various concentrations, the author tests the radiochemical hypothesis of constancy of the ionic yield a t the 50% level, y,/*. An original method of analysis of variance, made with Bartlett’s help, together with the introduction of an “operational dose,” shows that the equivalent statistical hypothesis (in Neyman’s sense to the radiochemical one) of constancy of a suitable regression coefficient @ is rejected a t the 1% level. The origin of the heterogeneity between the five concentrations that were irradiated is found in the most concentrated series. Two tentative explanations are given of this fact, one of these relating to Dainton and Miller’s work. Applications of Ion Exchange to Analytical Chemistry. EDWARD R. TORIPKINS. Ion exchange resins consist of a network or matrix made up of cross-linked long polymer chains with substituted functional groups. A number of types of exchange resins are available from commercial sources. Of these, the sulfonated polystyrene cation exchangers and the quaternary amine polystyrene anion exchangers have found the widest applications in analytical chemistry. The selectivity that an exchanger exhibits for one ion over another has been shown to depend upon the radii of the hydrated ions and the charges of the competing ions. For conditions under which exchangers usually are used in analytical procedures-Le., solutions less than 6 N in concentration in contact with the exchanger-the higher the valency and the smaller the ionic radius, the more preferentially will the ions be taken into the exchanger. The molal exchange constant, Km,for a system with two competing ions can be estimated by determining the concentration of each ion in each of the two phases. Hon-ever, this is not constant for wide variations in the ratio of one ion t o the other in the resin. To obtain a “true” constant, K , it is necessary to determine the activities of the ions in both phases. Ion exchangers are used in analytical chemistry to prepare samples for analysis by removing interfering ionic substances, by stoichiometrically substituting an ion in solution with a more readily determined ion on the resin, and by isolating one or more substances for analysis by selectively eluting them from an exchange column. Also, they may be used t o determine physical chemical properties of ionic solutions. For the latter application it is customary to use an equilibrium or batch method. The other uses involving separations are usually performed by flowing the ionic solution through a column of exchanger. Ion exchange has found its widest application in analytical chemistry for the removal of interfering ions prior t o a determination of a substance. I n many precipitation reactions the weight of the precipitate may be affected by the presence of certain other ions. The yield may be either too high if the coprecipitate or too low if they form a complex with the ion being determined. Usually these interfering substances can be separated easily from the substance being determined by passing a solution of the sample through a column of exchanger. If the interfering ions are of opposite charge to the ion being determined, they can be exchanged on the column, and replaced by noninterfering ions. I n this case the effluent solution and washing water are collected and analyzed in the usual manner. When the interfering ions have a charge of the same sign as the substance being determined, it is necessary to exchange both on the column and selectively elute them. This is somewhat more difficult to do, particularly when the two ions are similar. I n some instances it is possible to substitute an easily determined ion in the exchanger for one difficult t o determine in a solution. Since all exchange reactions are stoichiometric, the quantity of the ion originally in the solution can be calculated after the amount of the replaced ion in the effluent has been determined. Several theories have been proposed to explain the behavior of solutes being selectively eluted from exchange columns. The plate theory, although limited in the range of conditions t o nThich it applies, is the most useful one for predicting easily the degree of separation of solutes. Special devices for recording the concentration of various substances in the effluent are useful when a series of similar ions such as rare earths or amino acids is being separated. I n many instances the elution curves f r o g these recorders can be analyzed by application of the plate theory, and the quantity of each solute
ANALYTICAL CHEMISTRY
1524 may be estimated even when they have not been completely separated Approaches Utilized in the Development of Spot Tests. PHIIJI’ 15;. TV E ST
-1 diccussion was presented that summarized sonic of the approaches that have been used in the development of spot tests. It wac pointed out that it is desirable to have specific reagents where possihlr and that such reagents should be sensitive. I t was also pointed out that by noting the type of reactions that are undergone by a giveii reagent, it is possible to appraise its general usefulness and anticipate possible limitations. PPomising reagents can be improved in many instances by preparing derivatives of the parent compound. By proper conditioning of test reactions, it is possible to obtain specific, reactions, although the reagents used may not themselves be specific in their action. In connection with the development of conditioned reactioiib, it was suggested that there is more hope for the improvement of analytical tests through this approach than there is through the immediate development of new reagents that are entirely specific. The cvonditioning of reactions is ordinarily accomplished by means of controlled pH, the oxidation or reduction of interfering substances, and the selection of special reaction environments. Conditioning technique$ may also include separation procedures such as complexation, rapillary scparations, extraction, precipitation, chromatographic separations. and volatilization. I t is often possible t o include separations in such a way that they become an integral part of the spot-test procedure and do not cause undue complication of the test itself.
Instrumental Approaches to Paper Chromatography. M~~LLER
n u d e between assays of adrenaline carried o u t o n hexamethonium-treated cats with those carried o u t on spinal cats. T h e spinal cat gave a greater precision. Results obtained o n a numbcr of commercial preparations of adrenaline cream were described. 9 niceting of the society d l IJV held October 1 in London when t h e following papers will be presented: Spectroscopic Properties of Vitamin A?. Application to t h e Assay of Cod Liver Oils. H. R. C A M AASD R. A. MORTOX. Chromatographic Method for Determination of Cholesterol in Urine. RONALD A. bICALLISTER .iKD KENKETH HOWELLS. Simultaneous Determination of Pentose and Hexose. IT. T i .
m.
FERSELL AND H. K. KING.
T h e fifteenth sunimer meeting of the North of England Section
{vas held in Llandudno from June 13 t o 16. A paper was read by
J. Haslam on “The Analyst, in the Plastics Industry,” incorporating exhibits of plastics products in common use. A t t h e meeting of the section held in Manchester, April 25, R. Belcher discussed “Some Kew Methods in Analytical Chemistry,” including some n e x redox indicators, oxidimetric and reductimetric reagents as new titrants, some recent organic reagents as new precipitants, and advances in the determination of a few selected elements.
DORISC L E G ~ ,
The theoretical aspects of paper chromatography caii he Jtudietl with the aid of semiautomatic instruments. Recent instrument.. used by the author have been based on the square-law behavior oi the ascent or descent of liquid in a strip or sheet of paper. .In iniproved optical scanner for examining chromatograms has proved aucceseful in these studies-for example, in delineating the shape of :L band and evaluating Rj values more closely. Adequate information is now available on the factors determining the flox of a single liquid through paper. The outstanding problem is the application of this information to binary mixtures, as pya(’tioal chromatographic separations depend on the distribution ot solutes between two solvents, or on selective adsorption on the papet fibers, which is controlled by the composition of the binary solvent.
Society of Public Analysts summer meeting of the Biological Methods Group, Society of Public Analysts a n d Other Analytical Chemists, June 12 a n d 13, the following demonstrations of work in progress were shown at. the laiuoratoria of Roots Pure Drug Co., L t d . , West Britlgford, England. T THE
A
Pharmacology Division, Research Department. Cheniotherapy Section. Methods used in investigating new drugs for the treatment of some tropical diseases; Cartesian-diver micrometabolism apparatus for investigation of protozoan metabolism. Pharniacology Section. Guinea pig bronchioles, antihistamincx assay; drtection of local tissue damage; testing local anesthetics. Physiology Section. Granuloma test for cortisone activity. Tumor Section. Screening tests for tumor inhibitors. Bacteriology Division. Antibiotic Section. Antibiotic screening; experimental fermentation units; metabolic studies on antibiotic producing microorganisms. TB Chemot,herapy Section. I n vitro screening of antitubercular agents a n d morbid histology. General Chemotherapy Section. Bacterial a n d fungi screening of new chemotherapeutic agents; phage tests as a guide to selecting new viricides; vaccinia and Rous sarcoma in egg. Bioassay Division, Standards Department. Work in progress oil insulin for potency using mice a n d for delay activity using rabbits; heparin using sulfated ox blood, vitamin D using rats, gonadotrophin using rats, pituitary (posterior lobe), and pyro-
grns.
At the scientific section a paper on “Assay of Adrenaline in Adrenaline Cream,” by G. F. Somers, was presented.
.4 method was described for the extraction of adrenaline from adrenaline cream prior to biological assay. A comparison was
Pittsburgh Conference on Analytical Chemistry T h e Analytical Chemistry Group of the Pittsburgh Section of t h e AXIERICAK CHEMICAL SOCIETY and the Spectroscopy Societj of Pittsburgh have announced a Pittsburgh Conference on Analxtical Chemistry a n d Allied Spectroscopy, to be held a t t h e \\‘illiam Penn Hotel, Pittsburgh, Pa., March 2 to 6, 1953. Contributed papers are welcome on all phases of analytical (*hemistry, emission spectroscopy, infrared and ultraviolet spectroscopy, mass spectrometry, and x-ray diffraction a n d fluorescence analysis. Abstracts should be sent before December 1, 1952, t o L. E. Pitzer, Chairman, U. S. Steel Co., 525 Wm. Penn Place, Pittsburgh 30, Pn. During t h e conference regular meetings of the following ASTM committees are planned: D-2 on Petroleum Products and Lubricants, Research Division I V on Hydrocarbon Analysis, Section F, E-2 on Emission Spectroscopy, E-13 on Absorption Spectrosc.opy, a n d E-I4 on Mass Spectrometry. Mass spectrometry groups will meet, a n d Coniniittee D-14 is sponsoring papers on this subject. An enlarged exhibit of chemical and spectrographic 1:it)or:itorv equipmpnt n d l hr a feature of the conference.
Tenth Annual Pittsburgh Diffraction Conference. Mellon Institute, Pittsburgh, Pa., November 0 and 7 American Institute of Electrical Engineers. Technical Conference on electrically operated recording and controlling instruments, Benjamin Franklin Hotel, Philadelphia, Pa., November 17 and 18 Society for Experimental Stress Analysis. Annual meeting and exhibition, Hotel McAlpin, New York, N. Y . , December 3 to 5 Sixth Annual Symposium on Modern Methods of Analytical Chemistry. Louisiana State University, Baton Rouge, La., February 2 t o 6, 1963 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. William Penn Hotel. Pittsburgh, Pa., March 2 t o 6, 1953 Sixth Annual Summer Symposium. Rensselaer Polytechnic Institute, Troy, N. Y . , June 1953
