THE CHEMICAL WORLD THIS WEEK reported the results of a number of column separations of substances with similar properties. He said that this method is unique in its ability to produce extremely pure preparations of members of the lanthanide and actinide rare earth series. Also it has been used successfully in separating and purifying zirconium and hafnium, the alkaline earth elements, scandium, and man)· other metallic ions as well as a number of organic substances.
Evils a n d Advantages Detailed For Separations Procedures C & E N REPORTS: T h i r d Summer Symposium on A n a l y t i c a l
C O L l ' M B L S , O H I O . - T h c hist thing to do about separations procedures in analytical problems is to get rid of them. This was the advice of M. G. Mellon, keynoter for the third summer symposium held here June 16 and 17, eosponsorcd by the ACS Division of Analytical Chemistry and Analytical Chemistry. Setting the scene for the two-day session at Ohio State* University on the "Hole of Separations in Analytical Chemistry," Dr. Mellon pointed out that in recent years analysts have begun to follow the lead of chemical engineers in referring to different steps in various kinds of chemical and physical procedures as unit operations. So considered, any method ot analysis consists always of at least one, and usually of several, unit operations. Their number and nature depend upon the characteristics of the sample material and upon the kind and quality of information wanted. Separation, if used in a method, is one of these unit operations. It is safe to say, Dr. Mellon continued, that no analyst would voluntarily select a method involving a separative operation if an otherwise equally satisfactory nonseparative method were available. Separations take time and money. The equipment required may b e expensive and require skilled operators. Finally, analysts of wide experience recognize that, with the probable exception of sampling heterogeneous materials, separations are likely to be the seat of the most numerous and serious errors in many methods of analysis. Obviously it is impossible to get rid of all separations. Dr. Mellon stated, and as long as they are with us they offer an almost inexhaustible supply of analytical research problems aimed at improving or eliminating separative operations. One striking example of progress in avoiding separations is found in many recent adsorptimetric methods, especially those based on measurements in the infrared region of the spectrum. Routine infrared work, particularly in the petroleum industry, regularly yields data for half a dozen constituents in a multieomponent distillation fraction. Following Dr. Mellon's address the symposium was devoted to papers reviewing the latest developments in specific methods of separation. Among them was a paper on partition chromatography and countercurrent distribution by Lyman C. Craig of the Rockefeller Institute for Medical Research. He reported that recent work in his and other laboratories has confirmed the fact that this process is indeed highly effective for fractionating small amounts of certain solutes, but it
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also lias been shown that the process is by no means so simple as was originally thought. Adsorption effects appear to play a considerable if not the main role, both directly and indirectly. Aside from this uncertainty. Dr. Craig stated, all the A Tool of Analytical Chemistry other variables inherent in Tswett chromaMr. Schubert's paper pointed out that tography also must be considered. the chief service of ion exchange techTheories of chromatography, or of any niques to analytical chemistry is to provide continuous fractionation process, must of a simple, rapid, and effective tool for necessity be based on evidence obtained separating, concentrating, and isolating by rate studies and by attempts to corsubstances so that a direct gravimetric, relate· and explain separation effects. Divolumetric, or radiometric operation will rect evidence is difficult to obtain and a complete the analysis. He discussed a theory satisfactory in every respect has number of specific analytical uses of ion not been obtained. However, if the effect exchange re-actions to illustrate general is to be explained by analogy to a disprinciples and methods. Some of these continuous liquid-liquid extraction process were: isolation of radioéléments from an excellent basis for comparison is preurine, determination of traces of copper sented by the results of countercurrent in milk, composition of atmospheric condistribution which is a strictly discontaminants by concentration of the ions in tinuous process operating at equilibrium, rain water, determination of phosphorus he said. Here each equilibrium cell will in phosphate rock, determination of total contain a fraction of the original solute base in blood, preparation of carbonatewhich will coincide exactly with a cerfree sodium hydroxide, and many others. tain term of the appropriate binomial exAnother important method of separapansion. According to Dr. Craig, calculation, distillation, was reviewed by Arthur tions have been checked with a train up Hose of Pennsylvania State College. Coverto 2 2 0 extraction cells in length and with ing both theory and practice, h e outlined many different systems. Thus, he said, the methods of obtaining and using basic there cam be no question as to the theorx data such as the relative volatility of a when ideal solutes are involved. material, the number of theoretical plates Another paper on some theoretical asin a column, the reflux ratio, and the pects of adsorption chromatography was charge composition. He also suggested presented by Arthur Le Rosen, Louisiana methods for dealing with complicating State University. He described his work effects of procedures such as variable relain studying the interaction between solute, tive volatility, presence of multiple comsolvent, and adsorbent. He proposes that ponents, or changing reflux ratio. chromatographic adsorbents b e characterized in terms of flow rate and in terms of T h e formation of solid solutions in adsorption affinity for various molecular precipitation reactions was discussed by structural features. Dr. Le Rosen reported that in the W m . L. Evans, professor emeritus at OSU and former adsorption of organic com- ACS President; C. W. Faulk, professor emeritus at pounds from solution on O S U , toastmaster at dinner meeting; and G. T. Wernimont, chairman, Division of Analytical Chemistry noncarbon adsorbents, the main interactions are due to electron-sharing reactions, including hydrogen bond formation as an especially important case. According to the author, these principles should permit the selection of the most suitable absorbent for a given purpose. Ion exchange separations were discussed in two papers by Edward R. Tompkins of Scientific Service, Inc., and by Jack Schubert of Argonne National Laboratory. In the first the author reviewed the properties and laboratory applications of some of the commercially available exchangers. Mr. Tompkins also
CHEMICAL
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THE CHEMICAL WORLD THIS WEEK Siniultanroxisly, a S3.5 million plant for stitute of Technology explained the diffiI. M. Kolthoff of the University of Minprocessing phosphorus into t h e usual culties of separating very small amounts nesota. I le explained that when a constitugrades of s o l u b l e phosphates will b e of radio elements or the preparation of ent in a solution is soluble in a given solid, erected at Lawrciur, Kan. carrier-free isotopes. H e described the coprecipitation of this constituent takes Engineering-construction contract for procedure devised for the quantitative place during the r>reeipitation of the solid detailed design and construction of t h e s e clectroseparation of 10 ° grams of silver from the solution. Dr. Kolthoff said that units has bee^n let to Bechtel Corp., San as a useful model on which to base future this type of coprecipitation has been a Francisco. Responsibility for basic d e studies. nuisance. He believes an understanding sign is in the hands of John D. Anderson, of the fundamental laws governing solid T h e final two papers of the symposium chief engineer of the division, and his solution formation is essential to minimize were devoted to extraction. G. II. Morstaff. Completion of both units is c o n errors caused b y it. Not only that—but rison of the U. S. Atomic Energy Comtemplated by late spring of 1951. coprecipitation by solid solution formamission reviewed the general role of this tion can be used to great advantage in technique in analysis. Therald Moeller Colgate-Palmolive-Peet t h e quantitative precipitation of traces of and Dale Jackson of the University of Completes Major Improvements certain constituents from a solution. Illinois described a method for the exDr. Kolthoff gave examples in which traction of rare earth elements. T o keep p a c e with the continued growth t h e solubility of a precipitate is of a much of its business on the West Coast, Colgate1951 Symposium higher order of magnitude than correPalmolive-lVft Co. is now modernizing and sponds to a simple mass action law calT h e symposia committee has announced expanding i t s West Coast manufacturing culation. In order to precipitate such that the 1951 summer symposium will b e plant in Berkeley, Calif, Mr. E. H. Little, traces quantitatively, it is not sufficient to held in Washington, D . C , June 14 to 16. president, h a s announced. The new buildadd a carrier, h e indicated. Unless there The program will b e jointly arranged with ings already completed include a new is solid solution formation, the solubility the National Bureau of Standards which ofiice and toilet article plant, a new plant will be the same as in the absence of a will be celebrating its fiftieth anniverfor manufacture of Colgate's synthetic decarrier. sary then. The subject of the symposium tergents Vel and Fab, a dispensary buildOther phases of precipitation were is "Standard Samples and Standard ing, and warehouse extensions. covered by ïî. II. Willard in his paper Methods." Charles E. White. University T h e Vcl-jPab project reached its final o n separation by precipitation from homoof Maryland, has been named program stage recently when a shakedown run was geneous solution and by P. J. Elving and chairman and II. A. Bright, National made. This new spray-products plant conR. E. Van Atta in their discussion of t h e Bureau of Standards, local arrangements sists of five stories and basement. It is separation and determination of alkaline chairman. built of architectural reinforced concrete earth metals. In the latter paper t h e and structural steel throughout and conauthors reported that barium, strontium, W e s t v a c o Elemental Phosphorus tains 53,000 sciuare feet of floor space. and calcium can b e quantitatively sepaFacilities Being Increased Instrument controls are widely used to rated as readily filterable sulfate precipikeep the plant's precise standards of operatates by digestion of an aqueous methanol Westvaco chemical division of Food tion at a high level of efficiency. solution containing dimethyl sulfate. Machinery & Chemical Corp., whose headT h e new toilet article building and S. E. Q. Ashley of the General Electric quarters are in the Chrysler Building, office has total floor s p a c e of 6-1,000 feet Co. reported that electrolytic separations N e w York City—headquarters of the parand contains equipment for the manufacin the past have been to a large degree ent corporation being in San Jose, Calif.— ture and distribution of the Colgate line nonselective. T h e y have been specific in will construct a third electric furnace unit of toilet articles. As a result of the new method and generally empirical. Their for manufacture of elemental phosphorus and improved facilities, the Colgate plant reproducibility has not been good and at its Pocatello, Idaho, plant, where t w o at Berkeley provides m a n y new permanent their use therefore limited. He said, h o w phosphorus furnaces are presently in job opportunities; 950 persons are now emever, that recent and current developoperation. Power will come from the» ployed. T h e plant operations absorb more ments are showing the means by which hydroelectric system of the Idaho Power than $2.5 m i l l i o n worth of western raw selective results may b e achieved. Co., phosphate rock from the near-by d e materials euch ν ear. posits on the Fort Hall Indian reservation. L. B. Rodgers of the Massachusetts InLeft. W m . B. MacNevin, head of the division of analytical addressed dinner meeting on "Seeing Light and Color." Right. chemistry at O S U and chairman of committee o n local arH. A. Laitinen, University of Ellinois and general chairman rangements. Center. Ralph M. Evans. Eastman Kodak C o . , of symposium, with M. G. Mellon who gave keynote address
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