V O L U M E 2 2 , N O . 1, J A N U A R Y 1 9 5 0
61
Light Hydrocarbon Mixtures," Southwest Regional hleeting, AM.CHEM.Soc., Shreveport, La., 1948. Lappin, G. R., J . Chem. Education, 25, 657 (1948). Love, R. M., Padgett, A . R., Seyfried, IT. D., and Singleton, H . >I., ANAL.CHEM.,19, 3i-42 (1947). Machemer, H., Chemie-Ing.-Tech., 21, 58-60 (1949). Mallory, 0 . E. and Love, R. F.. A N A L . CHEM.,20, 94 (1948). Martin, K. J. L.. .lustralia. ('oiinril 8ci. Ind. Researrh, Bull. 197 (1946).
Miller, A. J., Psfroleiim Eugr. (Heferenve .\nnual), 21, ('40-44 (July 1949). Miller, G. H., and Woodle. It. A , "n-Heptane-2,2,4-Trimettiylpentane as a Test Mixture for Fractionating Column Evaluation," Division of Petroleum ('hemistry, 116th Meeting, AM.CHEM.Soc., 1949. Miller, P. G., Zinimerman. P. Id.,and Oberg, E. B., J . Dairy S c i . . 31. 189-98 11948).
Mirel, 'SlL., Kouba, D. L.. and Brrkrr, W.IT., A s v a t . . CHEM.. 20, 1065-6, (1948).
Moore, R. G. D., Chemist-Analyst, 37, 66 (1948). hIol,ris, H. E., Lane, W.H.. and Stiles. R . B., AN.AI..CHEM., 21, 998-9 (1949).
Mueller, J. H., J . Am. C'hem. Soc., 71, 1505-6 (1949). Murhead, G. S.. Indicstria y gidmica (Biienos A i r e s ) , 10, 4 (1948).
Myles, >I., Feldnian, J., Wender, I.. and Orchin. M.,"Fractionating Efficiency of Various Packingh in Operating a t Reduced Pressure," Di Chemistry, 116th Meeting, AM.CHEX.So(.., 1949. Nord, M., C'hem. Eng., 55, No. 11, 154 (1948). Phillips Petroleum Co., Chrm. Eng. S e w s , 27, 3240 (1949). Picon, AI ., B u l l . soc. chim. Fvance. 1949, 296-300. Ponierantz, P., Mears, T. W., and Howard. F. L., J . Research S a t l . Bur. Standards, 42, 617-32 (1949).
Quaife, M. L., and Harris, P. L., AN.AI..('HEM., 20, 1 2 2 L 4 (1948).
Reavell, J. A.,
(69) Robey, R. F., and Wiese. H. K.. A ~ Y A L CHEM., . 20, 926-33 (1948). (70) Rolfaon, F . B., Penther, C. J., and Pompeo, D. 6 . , Ihid.. 20, 1014-9 (1948). (71) Rose, Arthur, Ibid.. 21, 81b4 (1949). (72) Rossini, F. D., Frontirrs in Chemistry, 7, 157-82 (19401 (73) Rozengart, M .I., Csprkhi Khim., 17, 204-33 (1948). (74) Santiago. E. B., and Gonzales-Montes, L. M., Ion, 9, 27:i X i (1949). (75) Scallet, A. L., and E;hlr, O., Cereal Chem., 26, 174-81 (1949). (76) Scientific Glass Apparatus Co., Chem. Eng. .Yeic's, 26, 3790 (1948). ( 7 7 ) Sekino, M.,BuII. T7zs:t. P h y s . Chein. Research ( T o k y n ) ,22, 81i47 (1943). (78) Stnittenberg, J.. K e c . trac. chim., 67, 70.7-19 (1948) (in Engl (79) Starr, C . E.. J r . , .4nderson, J. S., and Davidson, V. M., A CHEM., 21, 1197-200 (1949). (80) Star!., C'. E., Jr., and Lane, Trent, Ibid., pp. 572-82. (81) Techtiicon (lo., ("hem.Eng. Seu.s, 26, 3269-70 (1948). (82) Ueno, S., and Tsuchikawa, H., J . SOC.Chem. I d . J a p u n 45. 203-6 (1942). (83) Ueno. S., and Yorozu, K., Ibid., 47, 680-1 (1944). (84) V. S. Technical Oil Mission, "Analytical and Practical Pre-
cision Fractionation of Hydi,ocarbon Mixtures," tr. fro111 Reel 170 by Consultants' Bureau. T P 690; by title only in U. S. Bur. Mines, Swthetic Liquid Fuels Abstracts, Noreniber 1948. (85) \'andoni, R., and C ' h a z t ~ r i ,M., MUBm. services ehim. &at ( P a r i s ) , 32, 25-30 (1945j.
(86) Vanossi, R., Anales asoc. quim. argentina. 36, 155 (1948). ( S i ) Wenger, W.J., and Ball, J. S., U. S. Bur. Mines, Rept. Incent. 4517 (1949). (88) Willits, C. O., John, 11. J., and Rose, L. R., J . Assoc. Offic. Agr. Chemists, 31, 432-8 (1948). (89) Ynfiesta, J. L., and Achon, M. .4.,Anales real soc. espafi. fis. y quim., Ser. B , 44, 689-94 (1948). (90) Zaukelies, D.. and Frost, A . A , , ANAL.CHEM.,21, 743M (19491.
Soc. C'hem. I n d . (Lortrlon), Chem. Eng. G r o u p ,
Proc., 26, (1944).
RECEIVED Sorrriil,rr It?. 194Cr
EXTRACT10N LYMAN C . CRAIG The Rockefeller Institute f o r Medical Research, .Yeu 1-ororh-,S. Y .
T
tlE prebent ieview is an attempt t o continue along the lines initiated by last year's review. Although in the main the wveragr is intended for papers dealing with analytical estraciions which appeared during the past year, no claim is made for canpleteness. dlmost any paper in the field of biochemistry or ot ganic, physical, analytical, or inorganic chcniistry potentially i*ould1ia\ e sectionb dealing lyith extraction which would be suit.il)lr for inclusion in the review. If refereiwe t o extraction has not 1)ccw made in the title and the article has not appeared in the in~lv\rsof Ciieinical Abstracts as a paper on ?.;traction, it ill prohI hlv not be mentioned herr EXTRACTION FOR RE\.IOVAL PURPOSES
Ikllatively few papers dealing with simple extraction for renioval purposes have appeared during the past. year and these h : L w been concerned mostly with apparatus. On the other hand, :i l:argei, number of papers have appearcd in which simple step\\ire countercurrent rstraction has been employed to advantage i l ir the separation of mixtures of closely related substances and as :I criterion of purity for a given prrparation. Unquestionably t.liis latter type of extraction will receive the greatest attention f i ) r t h c nest few years. The basis of this prediction is that app:tratu* have noxy been developed whereby thousands of quantit:tt,ive cxxtrartinns can be performed with but little labor. 31oreover, the past ycw has seen several cases where extraction has rezolved rnistur,rs of substances whose physical and chemical propcartics have made thrm unsuitable for fractionation hy nthrr kiiown procedurrs. Thr first, ronsider:ttion i n :tttrmptiny to use extraction for :t
given purpose is the choice of a suitable solvcnt. A favorable solvent greatly simplifies the procedure by making complicated apparatus unnecessary because a few simple extractions can then accomplish the purpose. The properties of solvents can be modified greatly by addition of the proper solutes. ,4n excellent example of this is provided by the interesting paper of Smith antl Page ( 3 5 ) . The possibilit,y of the use of simple extraction for rrmoving strong acids such as hydrochloric or sulfuric from aqueous solution would not occur to most chemists. Yet when the solvent is a chloroforni solution of a long-chain tertiary amine, such a~ dioctylmethylamine, rhlnride or sulfate ion can be removed t o the extent of 9870 bq- a single extraction provided strongly basic ions such as sodium or potassium are absent. Indeed, the method should prove t o be the nnc of choice for removing chloridc~nt'. sulfate ions from protein or peptide hydrolyzates. The unique dist,ribution is based on the fact that the amint. forms a salt which is preferentially soluble i n chloroform antl gives a water-chloroform partition ratio which greatly favors tfir organic phase. S o t all tertiary amines are able to do this. Thus triamylamine did not give the effect but, trioctylamine served thc. purpose. Alkaloid chemists have long kn0w.n that the hytlrochlorides of certain arom:ttica amines were more soluble in cIilori>form than in water. Streptomycin, a basic sugar derivative and a strongly h y h phylic substance, can be made t o part,ition preferentially in faror of an organic phase I)>- the use of a solution of one of the anionic. detergents. These agents have been called carriers by O'Keeffe, Dolliver, and Stiller ( 2 7 ) . .lmong the agents tested and found to he carriers were fatty a d s , alkylsulfonic acids, alkylsulfuric acids, and nrylsulfonic*:iclidr. Thr pH of the aqueous layer TV:~.;
62
found to be an important factor in the numerical value of the partition ratio. The same group of workers have also been able to partition heparin (28) by using laurylamine as the complexing agent. Heparin is a complex polysulfuric ester of a pol>-saccharide of high niolecular weight. One cannot help but wonder if certain proteins might not be partitioned with the appropriate solvents. Weizmann, Bergmann, Chandley, Steiner, Sulzbacher, and Zinikin ( 4 3 ) have made a study of the selective extraction of ethylene chlorhydrin. They found a distinct, dependence of the selective solvent poxer on the molecular size of the solvent. The effect could not be ascribed to a definite compound formation such as a hemiacetal when ketones or aldehydes were the solvent, but represented a more complex balance. Derivatives of furan were found useful for renioving fatty acids from aqurous solution (15). .1number of papers on the use of extractioii in the inorganic ficld have appeared recently. The method has been applied to the separation of certain compounds of iron (20, 44),mtimony (8), rhenium ( 4 1 ) , gold (23), uranium (go),zirconium and hafnium (4,18), cerium (,@), nickel and cobalt ( 1 1 ) , and thorium (33). Reasoning on the basis of the progress which has been made in related the field of organic chemistry in the separation of c1osc~l~homologs or isomers, one can predict that much xi11 I)e done by suitable countercurrent extraction and n-ith the proper understanding of solvents. From the data in t,he literature, a problem would appear to be the working out, of systems Lvhich give reasonably linear partition isotherms. I t is surprising that a more serious attempt has not already been made along this line. The correct evaluation of a continuous extraction process is not ah-ays easy and frequent,lyis oversimplified by the use of certain assumptions which in actual practice do not hold. How-ever, when the partition ratio remains nearly constant over a wide range of concentration, evaluation in terms of tin analogous ideal discontinuous process is not too difficult. But in practice often the partition &io changes so that extraction is f:tvored as the solute is progressively extracted and the solutiori beconics more dilute. The opposite also may occur. In either case, calculations become involved. Bewick, Currah, and Heamish (2) proposcd a method for the rapid evaluation of continuous extraction processes which includes a new value, the half extraction volume. They described an apparatus for carrying out comparative extractions and for gett’ing the data from lyhich the new value may be derived graphically. Tsai and Fu (40) have extended the mathematics and approach required for the analysis by simple extraction of mixtures of the lower fatty acids. Apparatus. Iisiao ( 1 7 ) and Lajh (21) have described niicroextractors which use a cold finger type of condenser. Hsiao found his design to be excellent for the estimation of the fat content in biological materials and to be much more rapid than the Soxhlet extractor. Kolb (19)encountered difficulty in applying the estractor of Hsiao to pulverized mouse muscle. He described a stepwise procedure and an apparatus which overcame the difficulties. When very small amounts of material are to be extracted, it is customary to use a small standard extractor. Evcii so, a much larger volume of solvent relative to the material to be extracted is necessary. Certain disadvantages such as introduction of impurities and promotion of transformation often accompany the use of too much solvent unless special prerautions are taken. Stern and Kirk (37) described an efficient microextractor which not only is suitable for cstracting small amounts of substance but also employs only a small volume of the extracting liquid. I t is designed so that the ensuing operations such as evaporation are most convenient. Chute and Wright (3)have developed a small laboratory continuous ext,ractor which is designed to operate under a pressure of .one or more atmospheres. Higher temperatures often contribute to more efficient extraction if the solute has sufficient solubility.
ANALYTICAL CHEMISTRY Nolan ( 2 5 ) gave the details for a continuous multiple extraction apparatus in which any number of analytical extractions up to 54 could be made simultaneously. I t could be used for liquidliquid ext.raction as well as for the extract,ion of solids. 1Iicaelli and Desnuelle (24) found a stepwise extraction of oil cakes to be more rapid and complrte than a Soxhlet extraction. They used a separatory funnel with a sintered filter sealed into the funnel so that the ext,ract could bc withdrawn from the solid k)y surtiori. EXTRACTION FOR FRACTIOh ATION PURPOSES
The success of extraction for fractionation purposes depends 011 a favorable state of affairs with regard to a number of factors nhich may be considered in three groups as follom: (1) mechanical considerations (apparatus); (2) availability of suitable systems and the required specificity or selectivity; (3) analytical and isolation procedures. All three bear a certain relationship or dependence on each other. Thus, if an unlimited number of quantit,ative extractions or their equivalrnt Jvere easily attainahle, the second consideration would be minimized, as a highly selective system would not be required to achieve separations. Conversely, if a sufficiently high selectivity can be found, tht. mechanical aspects are greatly simplified since only a few stages are required for separations and the apparatus can be very simple. The analytical difficulties depend on the systems chosen as \vel1 as on the number of estimations which may be involved. Where incomplete separations arc to be treated, both general and highly selective analytical method,? are desirable. During the past year progress has been made iii each of the three groups. Two of these will be treated separately. The third would include a review of the progress made in spectrophotometers, balances, and quantitative color reactions aud is too broad a subject to be covered here. Apparatus. Raymond ( 3 2 ) described a mechanically shaken countercurrent distribution appariit us for smaller numbers of trnnsfcrs which employed especially designed separatory funnel>. O’Keeffe, Dolliver, and Stiller ( 2 7 ) gave a useful separatory funnel procedure for larger volumes and for continuous introduction of solute. In this procedure a mixture is resolved into two fractions on a single passage through the series of funnels. Craig and Post (8)gave it description of several types of countercurrent distribution apparatug. The details of construction of a 54-tube steel apparatus with glass plates on each end and instructions for regrinding the surfaces were given. The 5Ptube apparatus can be operated so that it, is analogous to a continuous column with 54 theoretical stages in it. Several methods of operating the apparatus have proved useful for different separation These are the “fundamental” procedure, the “single withdra\val procedure, and the “alternate n-ithdranal” procedure. An all-glass type of distribution apparatus made with individual interlocking units was only briefly described ( 8 )since it had not been extensively tested. -in extraction train containing 108 such units was suhsequently built. This was immediately successful in separal ing polypeptides of bacterial origin ( 6 ) . However, esperience gained in this work snon suggested improvements. The present stage of development in the author’s laboratory includes a train containing 220 units of improved design. I t is fully automatic with electric niotoi’s and time clocks attached. If thtz single withdrawal technique is desired, provision is made for this by use of an automatic filling device and by integration of the Steiir and Moore chromatographic fraction collector (36) at the effluent end of the train. Thus the apptiratus can be operated in a manner entirely analogous to chromatography. The advantages of such equipment are obvious and inclucle the possibility of considerable expansion in regard t o both the number of units and the sim or capacity of each unit in the train. Systems. rllthough one can gain a fair idea from the study of individual partition ratios and partition isotherms whether or not the separation of a given niixtiirt, is possible, actual resolutiorr (11
63
V O L U M E 22, NO. 1, J A N U A R Y 1 9 5 0 I k i t , niixture by countercurrelit distribution is much more convincing and at the same time gives more pertinent information. Thc,refore the subject will be covered in this rcvieLv by referring to a c ~ u a lseparations madc with tht: countercurrent distribution t vchnique. C'ountercurrent distribution has been extensively used in 3eparating and characterizing the streptomyces antibiotics (27, S$? 31,58,39) following the discovery of certain solutes to promote the desired partition as mentioned. Fortunately from the standpoint, of separation, considerable specificity or selectivity appears to have been attained despite the complex equilibrium involved. Titus and Fried (39) made an interesting observation in regard io t antomerization. Theoretically tautomerization should give a 11isti.ibution curve wider than the theoretical for a single sub*tame, if the time of establishing equilibrium between t,he tautomers is greater than the time between transfers in the machine and provided the pure tautomers have different partition ratios in the qysteiiis employed. Since determination of purity with the distribution technique involves an experimental curve which coincides with the normal curve of error, one must consider the possitiility of tautomerization ith certain curves which consistently come t,oo broad. Titus and Fried were able to show that streptomycin can exist i l l several forms involving a change of st'ructure connected with thr aldehyde group in the streptose portion of the molecule. The uiilj- method used for detecting the tautomers Tvas their distribution curves. Yet clear evidence was presented and one of the rr~idily int,erconvertible forms was isolated in a high state of piiiity by use of the proper system and temperature. O'Keeffe, Russo-Alesi, Dolliver, and Stiller (28) studied the ilistribution of heparin by using laurylamine as the carrier. Two fractions were completely separated from each other. Both had heparin activity. With the start made on this type of substance, t l i c question as to how far such a n approach can be carried i? iol.en1ost. Saturally occurring compvunds of phosphorus such as the phosphatides have long been difficult t o fractionate and charact erize. Promise in the use of countercurrent distribution for this purposc is given by the Lvorl; of Scholfield, Dutton, Tanner, and C'omn ( 3 4 ) on so-called s o y h a n lecithin. ,iltliough the work ropoi~tedgave only a preliminary idea of the complexity of the mixture, it v a s sufficient to wiise considerable revision of the J.i(Sw3 previously held. A h x h e rt ~ a n i p l e dealing with a compound ot phosphorus is the purification of cozymase, the diphosphopyriiliiic nucleotide, by Hogehooni and Barry (16). I n this work :I Iliiinher of experimental difficulties were skillfully overcome. .\It hough the lack of a method for fractionatingand characteriziiig naturally occurring peptides has prevented the type of study tlie structural chemist prefers to do, nonet,heless the importance c:1' the field to biochemistry is well recognized. There are now :i vi1 ilable rapid methods (chromatography ) for determining c1ii:intitatively and qualitatively the amino acid content in hytlrolyzates but only laborious methods for isolating the amino ncidr i n more than micro amounts and no suitable methods for isolating peptides from partial hydrolyzates. I t ~vould seem onable, if not certain, that polypeptides occur ~videlyin natnre even if few have been isolated in the pure state. .\ degree of cautious hope appears to be warranted from the r r w l t s of a number of papers dealing with the use of countercurrc*iit distribution together with chromatography. Gorley ( 1 4 ) purified the polypeptide antibiotic, bacitracin, by countercurrent distribution. Craig, Gregory, and Barry ( 6 ) applied many more t runsfers to the purification and shoa-ed that it is perfectly posd d e to hydrolyze such a polypeptide and isolate the component, :iniino acids in an analytically pure form by extraction. The mounts isolated are sufficiently large so that unequivoral identication may be made by the classical procedures. Craig, Gregory, and Barry ( 5 ) were able t o fractionate gramii.itlin. tyrocidine. and gramicidin-s ench into familips of poly-
peptides. The iiidividual members of a family differed slightly b3 their amino acid components, but in some cases only by the stoichiometric proportions of the amino acids. 4 beginning has been made in the application of extraction for the proof of purity in the polymyxin antibiotics (1). Livermore and du Vigneaud (22) have purified the oxytocic hormone from the posterior lobe of the pituitary by countercurrent distribution and have given evidence for the purity of their prrparation. The substance is quite unstable and thrrefore estraction viould appear t o be the most promising approach. Perhaps this work represents a beginning toward a bettw understanding of such hormones. Woolley ( 4 5 ) isolated crystalline yellow peptides from the partial hydrolysis of insulin which had been reacted with dinitrofluorobenzenr. This approach t o unraveling the structure of proteins should become more promising n-it h thr. frasihility of' very high numbers of transfers. The separation of the individual phenolic substmces prevent in coal tar is a prohlem which has always been difficult. Golumbic, Orchin, and IYeller (13) and Golumbic ( 1 2 ) have taken up the study of the sepmition of the complex mixture of phenols produced during the liquid phase hydrogenation of coal. Their results show th:it t h P trchnique is ideally suited, in many respects, to the problcin. Phenols have characteristic- absorption spectra in the ultraviolrt, ii point which makes the analytical work easy and which contributes greatly to the specificity. The type of data these authors give is the type needed for all classes of organic substuices. Reasoning on the basis of the experience wit,h the quinoline synthetic antinialarials ( 7 ) , a countercurrent distribution should be ideal for separating the individual members of t,he closely related alkaloids which exist so commonly in nature. Fried, White, and Wintersteiner (IO)readily separated two new veratrine alkaloids by this techiiique from the amorphous residue which remained after the known alkaloids had been separated by the older published methods. A very interesting study in the separation of the :tzulene hydrocarbons has heen made by Plattner, Heilbronner, and Keber (30). Satisfactory partition ratios were obtained by using a system with a hydrocarbon such as petroleum ether or toluene for the one phase and a strong mineral acid such as vulfuric or phosphoric acid for the other. The strength of the mineral acid controlled the value (if the partition ratio. Lincar pwtition isotherms could be obtained a t Io~vcrccncentrations and equilibrium was established in less thnn :i minute as has been found with the different classes of suhst:trices studied elsewht~re. Data were given with the isomeric methyl azulenes to slioa- that separation would he easy particiil:rrly with the equipment now available in this counti'y. Brt:i values of the order of 2 or more were obtained. Shifting the ph:~sepair, for instance, from petrolic ether-sulfuric acid to tolueiie-sulfuric acid caused a consitlcr:ihlt~shift i n the p value for R giwn pair of isomers. LITERATURE CITED
(1) Bell, P. H., Bone, J. F., English, J. P., Fellows, C . E., Howard,
K. S.. Rogers. M. M..Sheoerd. It. K.. T17iiiterhottom. R.. Doinhubh, -1.C . , Kushner, S., and Suhbnltow. T.,Ann. S.Y . Acad. Sei.. 51,89i (1949). (2) Bewick, H. A , Currah, J. E., and Beamidi, F. L., A Y L I CHEY., , 20, 740 (1948). (3) Chute. TI7. J.. and Wright, G. F., Ibid., 21,193 (1949). (4) Connick. R . E., and McT'ey, W ,H., J . Am. Chem. Soc., 71,3182
(1949).
(5) Craig, L. C., Gregory, J. D., and Barry, G. T., "Amino Acids and Proteins," Cold Spring Harbor Symposia Quant. Biol. (1949). (6) Craig, L. C., Gregory, J. D., and Barry, G. T., J . Clin. Inaest.,
28,1014 (1949). (7) Craig, L. C., Mighton, H., Titus, E., and Golumbic, C., ds.4~. CHEY.,20,134 (1948). (8) Craig, L. C., and Post, O., Ibid., 21,500 (1949). (9) Ed%-aids,F. C., and Voigt, -4. F.,Ibid., p. 1204. (10) Fried, J., White, H. L., and Wintersteiner, O., J . A m . Chem. Soc.. 71,3260 (1949)
ANALYTICAL CHEMISTRY
64 (11) (12) (13) (14) (15) (16)
Garwin, L., and Hixon, A. N., I n d . Eng. Chem., 41, 2298 (1949). Golumbic, C., J . Am. Chem. Soc., 71, 2627 (1949). Golumbic, C., Orchin, M.. and Weller, S., Ibid., 71, 2624 (1949). Gorley, J. T., U.S. Patent 2,457,887 (1949). Guinot, H. M., and Chassaing, P., Ibid., 2,437,519 (1948). Hogeboom, G. H., and Barry, G. T., J . Bid. Chem., 176, 935
(1948). (17) Hsiao, S. C., Science, 107, 24 (1948). (18) Huffman, E. H., and Beaufait, L. J.. .J. A m . C’hem. Soc., 71, 3179 (1949). (19) Kolb, J. J., Science, 109, 378 (1949). (20) Kuznetsov, V. I., J . Gen. Chem., (C7.S.S.R.),17, 175 (1947). (21) Lash, J. J . , Am. J . Clin. Pathology, 18, 584 (1948). (22) Livermore, A. H., and du T’igneaud, Y.,,J. Biol. Chem., 180, 365 (1949). (23) McBryde, W.A. E., and Yoe, J. H., A s i i . . (’HEY., 20, 1094 (1948). (24) Micaelli, O., and Desnuelle, P., Bull. meus. ITERG, 1948, No. 7 , 31-3. (25) Nolan, L. S . , ANAL.CHEY.,21, 1116 (1949). (26) Norstrom, 9., and Sillh, L. G., Snensk. Kern. Tid., 60, 227 (1948). (27) O’Keeffe, 9. E., Dolliver, M.A., and Stiller, E:. T., J . Am. Chem. Soc., 71, 2452 (1949). (28) O’Keeffe, -4.E., Russo-Alesi, F. M., Dollirer, M.A . , and Stiller, E. T., I b i d . , 71, 1517 (1949). 129) Peck, R. L., Hoffhine. C. E., Jr.. Gale, P.. and Folkers. K., Ibid.. p . 2590.
(30, Plattner. A . Heilbronner. E.. and Weber. S.. H e h . Chim. d c t u . 32,574 (1949). 131) Plaut. G. W. E., and Mr Coinlack, R. B.. J . .Im. Chem. Soc., 71, 2264 (1949). (32) Raymond, S., ANAL.CHEY.,21, 1292 (1949). (33) Rothschild, B. F., Templeton, C. C., and Hall, 9.I . , J . /’h,ys. and Colloid. Chem.. 52, 1006 (1948). (34) Scholfield, C . K., Dutton, H. J., Tanner, F. W.,J r . , and (‘owati, J. C . , J. Am. Oil Chemists’ Soc., 25, 365 (1948). (35) Smith, E. L., and Page, 6.E.. 6.Soc. Chem. Ind. ( L o n d o n ) ,67, 4h (1948). (36) Stein, W. H., and Moore. S..J . Bid. Chem., 176, 337 (19481. (37) Stern, H., and Kirk, P. L., Ibid., 177, 43 (1949). (38) Swart, E. A., J . Am. f‘hrm. Soc., 71, 2942 (1949). (39) Titus, E., and Fried, J.. .I. B i d . Chem., 174, 57 (1948). (40) Tsai, K. R., and Fu. Y . , As.LI,. CHEM., 21, 818 (1949). (41) Vanossi, R., Annlrs. sor. c i e n t . Argrnfinn, Seccidn Santu F e , 145, 207 (1948). (42) Warf, J. C., J . Am. (‘hem. SOC., 71, 3157 (1949). (43) Weizmann, Ch., Bergmatin, E., Chandley, E. F., Steitier, €1.. Sulzbacher, M., arid Zirnkin. E., J. Snc. Chem. I d . (London), 67,203 (1948). (44) Wells, J. E., and Hunter, D. P., AnaZUst, 73, 671 (1948). (45) Woolley, D. IT., J . B i d . Chem., 179. ,593 (1949).
RECEIVEDNovember 23,
1H49
ION EXCHANGE ROBERT KUNIK Resinous
I
I’rodiicta Diitsion,
Rohm & Haas Company, Philadelphia, Pa.
p\’ LAST year’s review ( 1 4 ) of the application of ion exchange
techniques to analytical chemistry, the basic principles of ion cxchange and the general nature of ion exchange materials were reviewed, in addition to the analytical applications. During the past year, considerable progress has been made in the use of ion exchange as a n analytical technique. I n particular, ion exchange materials have provcd themselves to be useful both in chromatography and in conventional analytical methods. I n the latter case, the removal of interfering elements has been simplified in sclveral conventional analytical procedures. LITERATURE REVIEWS
In a chapter of a recent book on ion exchange, Rienian (18) has reviewed and classified the analytical applications of ion exchange. Its use in the laboratory, in particular, the chromatographic te*chniques,has been reviewed by Tompkins (27, 28). The usefulness of ion exchange in rare earth and radioisotope chemistry has been discussed critically by Cohri, Parker, and Tompkins (6) and Steacie and Cambron (23).
ions was accomplished on the sanie resin, utilizing identical chromatographic techniques. The separation of the ribosr nucleosides, purine, and pyriinidiiw fragments of yeast nucleic acid has been accomplished in a most spectacular manner by Cohn ( 3 , 6 )using both anion and cation cxchange resins. Utilizing a sulfonic arid cation exchanger, Cohii found i t possible to separate completely the purine and pyriniidine bases, uracil, cytosine, guanine, and adenine. I n order t o separate the nonionized bases, t,hymine and uracil, as well as the other bases, Cohn employed a strong base anion exchanger as the adsorbent. The separation of the nionoribosenucleic acids (uridylic, guanylic, cytidylic, and adenylic acids) has been accomplished by Cohn on a sulfonic acid exchanger. Bzcause the acids exhibit but slight basicity, their elution from the column was effected with a weak acid. The method perfected by Cohn ( 4 ) is suitable for most laboratories, as the chromatographic development can be readily followed and traced by means of spectrophotometric ahsorption techniques in the ultraviolet (260 to 265 mp) region. Refinements in the ion exchange separation of amino acids have been made by Rauen and Felix (21) and by Partridge (bo), the lattcr utilizing the Tiselius displacemcAnt techniqur.
IOh E X C H 4 h G E CHROM4TOGRAPHY
The separation of closely related ionic species by chromatographic techniques utilizing an ion exchange resin adsorbent has been applied successfully t o several interesting inorganic and organic mixtures. Utilizing radioactive tracers, Tompkins (16)has shown that radium and barium can be fractionated in a manner similar t o the rare earth separations. The citrate complexing technique has been used t o develop into bands the constituents previously adsorbed on a sulfonic acid cation exchanger. Similarly, Street and Seaborg (24) have separated the closely related ionic pair, hafnium-zirconium. Kraus and Moore (12, 13) have employed a most interesting technique for the separation of the pairs, zirconium-hafnium and columbium-tantalum, utilizing anionic complexes of these ions. Oxalate and fluoride complexes of zirconium and hafnium were chromatographically separated on an anion exchanger of the strong base type. The complete separation of columbium and tantalum as the CbF,-- and TaF;,--
REMOVAL OF INTERFERING ELEMEETS
Of considerable interest has been the utilization of ion escliange methods for removing intprfering constituents. In many convcntional methods of analvsis, anions interfere in the analysrs of several cations. Inasmuch as oppositely charged ions can be separated by means of ion exchange, these interfering ions can be removed readily. Sodium cannot be determined as either the zinc or magnesiuni uranyl acetate in the presence of phosphates, molybdates, and ot,her anions that are capable of forming irisoluble precipitates with the uranyl acetate reagent. Klement and Dmytruk (11)recommend the removal of phosphates by means ot an anion exchange resin prior to the precipitation of the sodium. Linqvist (16) suggests the adsorption of sodium on a cation t:xchanger in order to separate the interfering elements. FIowrwr. this latter method requires the additional acid elution str,p prior to thc sodium precipita,tion.
