Review of Fundamental Developments in Analysis
Ion Exchange Chromatography Robert Kunin and
F. X.
McGarvey, Rohm & Haas Co., Philadelphia, Pa.
0
of the most useful applications of ion exchange in analytical chemistry is the field of ion exchange chromatography. In many ways, ion exchange chromatography differs very little from the general area of solution adsorption chromatography and it may be considered as a special case of adsorption chromatography. In preparing this review on ion exchange chromatography, which covers the period November 1959 through KOvember 1961, the authors had the choice of including published material in which only ion exchange phenomena were involved during the chromatographic process or including published material in which ion exchange substances are used as the sorbent regardless of whether or not an ion exchange process is involved during the chromatographic process. The latter would then include gas chromatography on Molecular-Sieve zeolites and various solution chromatographic processes on ion exchange resins involving ion exclusion, salting-in, and solubilization principles. Except for the case of the gas chromatography on hfolecular-Sieve zeolites, all phases of chromatography on ion exchange media will be considered. NE
THEORY
The various general theories of chromatography, particularly the mathematical treatments, can be applied to ion exchange chromatography. However, application of the general theory demands an appreciation of the equilibrium and kinetic behavior of ion exchange material. Application of ion exchange to chromatography also demands a working knowledge of the relationships between the structure, both physical and chemical, of ion exchange materials and their behavior. Some tests of the chromatographic theory to the separation of isotopes on ion exchange materials have been made. Knyazev (JA) has found that the separation of isotopes as cations on cation exchange resins depends largely upon the degree of cross linking of the resin and the nature and concentration of the electrolyte. Lee (4A), investigating the separation of the lithium isotopes on various inorganic and organic cation exchangers, had con48 R
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ANALYTICAL CHEMISTRY
cluded that the carboxylic acid resins and the inorganic exchangers are as efficient as the sulfonic acid resins but that the phosphorous and phosphoric acid resins are inferior by an order of magnitude. Lee postulates that the degree of hydration of the lithium ion in the resin phase determines the magnitude of the isotope separation factor and that any factor that m-ill dehydrate the ion will increase the factor. Studies on the plate theory as applied t o ion exchange chromatography were made by Toshikiko, Okazaki, and Hiroe (7A) for ions of unequal valence and by Meleshko, Blekhina, and Pal’kina (5A) for ions of the same valence. Thomas (BA) has adapted Watter’s chromatographic equations to ion exchange chromatography. Theoretical approaches to the chromatographic separation of amino acids on a cation exchange resin were studied by Feigelson ( I A )and Hamilton, Bogue, and Anderson (2-4). NEW ION EXCHANGERS OF CHROMATOGRAPHIC INTEREST
The availability of many ion exchange materials suitable for ion exchange chromatography has been a vital factor in the growth of this technique. Most of these materials are readily available from most laboratory supply houses. New ion exchangers of interest to the analytical chemist are continually being developed. A review of interest to the biochemists is that of Guthrie and Bullock (SB) on the preparation and properties of the various anion and cation exchange celluloses now being used for the chromatography of proteins and related peptides. Paper chromatography and ion exchange chromatography have been wedded by the incorporation of ion exchange activity into paper by various techniques. Smillie (4B) has described the use of paper modified with finely divided ion exchange resins. Testa (BB) has modified paper by the addition of a liquid anion exchanger such as tri-n-octylamine. Caplan ( I B ) ,Yamabe, Seno, and Takai (7B), and Street and Niyogi (6B) have developed the use of ion exchange papers in electrochromatography. DaCosta and Jeronimo (gB) have added zirconium selenite to the list of inorganic
precipitates that have heen found useful in ion exchange chromatography. APPARATUS
Although the equipment used in ion exchange chromatography differs little from that employed generally throughout the field of chromatography, some useful mechanical devices have been devised for use with ion exchange materials. Lundgren and Loeb ( I C ) have developed an automatic device for the ion exchange chromatographic analysis of condensed phosphate mixtures normally present in detergents. BASIC TECHNIQUES
As noted above, ion exchange materials may serve as chromatographic substrates for separations which do not involve an ion exchange mechanism. Under these circumstances, the ion exchange materials serve as immiscible concentrated electrolytes for conducting separations based upon Donnan membrane equilibria (ion exclusion), salting-out phenomena, solubilization, etc Shi (7D) has made a general relierv of this topic and Rieman (6D) has reviewed his own work on saltingout chromatography. Lireyer and Rieman (20) have studied the influence of the nature of the organic substance being separated and the properties of the ion exchange resin upon salting-out chromatography. Jakob, Park, Ciric, and Rieman (50) h a w studied the separation of mixtures of phosphoric and phosphonic acids by this technique. Cesarano and Lepscky ( S D ) have studied the separation of mono- and dibutyl phosphate by ion exclusion. Helfferich ( 4 0 ) has suggested the use of ion exchange materials as ligand exchangers for the separation of ammonia and amines, polyhydric alcohols, organic acids, ete., by employing the ion exchange resin with a suitable complexing metal (Cu, Ni, Co) in its structure. The use of ion exchange resins in thinlayer chromatography has been suggested by Bobbitt ( I D ) . INORGANIC SEPARATIONS
Ion exchange chromatography is widely used throughout the world in inorganic analysis and, except for the in-
ert rare gases, procedures have been devised for the separation of all of the elements of the periodic chart. Wish (2SE) has developed a radiochemical ion exchange procedure for the determination of sodium and cesium. Various analytical procedures for the separation of magnesium and calcium on a cation exchanger have been developed by Charreton and Marie ( S E ) . hlajumdar and Dc (Is’E).Povondra et al. (18E), and Wade and Seim (%E) have studied similar techniques fur the separation of calcium and strontium. An ion exchange procedure for the determination of strontium-00 in milk has been developed by Porter et al. (176). -4multitude of papers, too numerous to rcvieTT properly here: appeared during the past two years on the ion exchange chromatography of the rare earth and actinide elements. Of analytical interest, hon-ever, are the reviews on this subject by Choppin and Chatham-Strode (@) and Ryabchikov and Terent’eva (19E). Separations of Zn, Cd, Ea, Zr, Fe, etc., using the complex elution technique developed for the rare earths have been studied by Khopkar ( I I E ) , hfarhoul (16E), Sagortschew (ZUE), Koslova, Ch’eng, and Scnyavin (12E), and Tsitovich (,%E). Of general interest in the chromatography of inorganic cationic species on sulfonic acid cation exchange resins are the studies of Mann and Swanson (14E) on the elution of A h j Fe, Ni, Cu, Zn, Cd, and Hg with HC1; of Strelow (2SE) on the elution of Be, Al, Fe, Y , Ce, and rare earths with HC1 and HSO,; of Fritz, Garalda, and Karraker ( 7 E ) on the elution of a series of cations that form complexes with H F ; and of Strelow (RQE) on the separation of trace elements in plant materials from ferric iron. lienge resins are also widely used in ion exchange chromatography of inorganic substances. Hague and Machlan ( 9 E ) have developed an analytical proccdure for the separation of Hf and Zr as the sulfate complexes on an anion exchange resin. A similar procedure has been developed by Bandi et al. (2E) for the analytical srparation of Zr, Ti, Kb> Ta, IT, and M o . The separat,ions wcre enhancpd n-hen complexing agents such as peroxide, citrate, or pyrogallol were added. hliyamoto (16E) has separated sulfate from selenate by anion exchange chromatography prior to the determination of sulfur in high purity selenium. Edge ( 6 E ) , JlXiins and Smith (,WE), Fritz and Pivtrzyk (RE), and Janauer and Korkisch (201;) have found that the addition of an organic solvent such as alcohol enhances the separations of various metallic complexes on anion exchange resins. Analytical chromatographic proce-
dures for the separation of uranium, thorium, and the trans-uranic elements on anion exchange resins have been developed by Edge ( 6 E ) , Adloff ( I E ) , Starik and Ginzburg (22E),and Starik and Amplelogova (22E ) . BIOCHEMISTRY
To a considerable degree, much of the published literature on the analytical use of ion exchange chromatography is in the field of biochemistry. A comprehensive review of this field has been prepared by Rotman (10F). The use of ion exchange chromatography for the analysis of amino acids has become so routine that this review Kill consider only new developments that are of general interest. For example, Hamilton ( S F ) has demonstrated t h a t with the aid of high pressures and very fine cuts of micron-sized sulfonic acid cation exchange resins, one can perform the automatic chromatographic analysis of amino acids a t high flow rates. Buchanan and Markiw ( Z F ) were able to separate several amino acids on a sulfonic acid resin with water elution. Knight ( 7 F ) has been able to apply the classic work of Moore and Stein to paper chromatography employing chromatographic paper “loaded” with finely divided sulfonic acid ion exchange resins. During the past two years, there have been developed several procedures for the ion exchange chromatography of proteins. Of particular interest have been the studies of Jackson et al. (4F), Anderson, Lepper, and Winzler ( I F ) , Steinbuch and Quentin ( 1 1 F ) , Yaguchi, Tarassuk, and Heinziker ( 1 4 F ) , and Jones and Parsons ( 6 F ) on the use of ion exchanger celluloses, particularly the anion exchange diethylaminoethyl cellulose (DEAE). Randerath (8F)has developed a procedure for the thin-film Chromatography of nucleic acid derivatives on strong base anion exrhangers. Wade ( 1 2 F ) , Rindi and DcGuiseppe ( 9 F ), and Jones and Curt (6F)have developed analytical anion exchange chromatographic procedures for the fractionation of sugar phosphatcs and other phosphate esters. Watanabe ( 2 W ) has demonstrated that several alkaloids of pharmaceutical interest such as berberine and strychnine can be analyzed by ion exchange chromatography on a carboxylic cation exchange resin. O R G A N I C CHEMISTRY
The analytical separation of various organic acids such as succinic, malic, tartaric, and citric acids on anion exchange resins has been studied by Dimotaki-Kourakou ( I G ) and Stinson, Subers, and Petty (6G). Skelly (6G) has developed a gradient elution tech-
nique for the separation of the isomers of tetrachorophenol. Jones, Wall, and Pittet (SG) have separated various oligosaccharides on the lithium form of a cation exchanger and Hallen (ZG) has developed a chromatographic method for the analysis of sugars based on the separation of the sugars as the borate complexes on an anion exchange resin. A chromatographic analytical procedure using cation exchange resin impregnated paper has b e m developed by Lewandowski (4G) for the sulfonamides. ACKNOWLEDGMENT
The authors acknowledge the assistance of Erich Ueitzner, Helen Tucker, and their associates of the library staff of the Rohm 8: Haas Co. K i t h o u t tnis assistance i t would have been impossible to obtain, review, or translate the many articles processed during the past two years. LITERATURE CITED
Theory (1A) Feigelson, J., J . Phys. Chena. 6 5 , 975 (1961). (2A) Hamilton, P. B., Bogue, D. C.,
Anderson, R. A., ANAL.CHEM.3 2 , 1782
( I 960). (3.4) Gnyazev, D. A., Zhur. Fzz. I i h i ~ n . 3 5 , 612 (1961). ( 4 h ) Lee, 1). .4.,J . Chem. Eng. Data 6 , 565 (1961). (5A) Meleshko, V. P., Alekhina, V. A., Pal kina, N. S., Trudy Voronezh. Gosundarst. Unav. 57, 47 (1959). (6.4) Thomas, G. W., Soil Sci. SOC.Am. Proc. 24,422 (1960). ( 7 h ) Toshikiko, hI., Okazaki, hl., Hiroe, K., Kagaku Kogaku 2 5 , 104 (1961).
New Ion Exchangers of Chromatographic Interest (1B) Caplan, S. R., J . Electrochem SOC. 108, 577 (1961).
(2B) DaCosta, 31. J. N., Jeroniino, X. A. S., J . Chronzaioq. 5 , 546 (1961). (3B) Guthrie, J. D., Bullock, ,4.L I Ind.
Eng. Chem. 5 2 , 933 (1960). (4B) Smillie, ST., J . Chronmtog. 4, 494 (1960).
(5B) Street, H. V., Xiyogi, S.K., Yature 190, 587 (1961). (6B) Testa, C., J . CIiro,natoy. 5 , 236 (1961). (7B) Yamabe, T., Seno, LI, Takai, N., Bull. Chern. SOC. Japan 34, 738 (1961).
Apparatus (IC) Lundgren, D. P., Loeb, N.P., .\NAL. CHEM.33,366 (1961).
Basic Techniques (1D) Bobbitt. J. >I Chem. ., Eno. N e u s ‘ 39,42 (1961). (2D) Breyer, A. C., Rieman, W.,111, Tolmntn - .... ..- 4. 67 - - (1960).(3D) Cesarano, C., ‘ Lepscky, C., J . Inorg. & Nuclear Chnn. 14, 276 (1!%0). (4D) Helfferich, F., Nature 189, 1001 (1961). (5D) Jakob, F., Park, E;. C., Chic, J., Rieman, W., Talanfa 8,431 (1961). (6D) Rieman. W.. 111, J . C h e n . Educ. 38, 338(1961).’ ’ ’ (7D) Shi, H. C., J . Agr. Chem. ( T a i w a n ) 9,40 (1960). - I
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VOL. 34, NO. 5. APRIL 1962
49R
Review of Fundamental Develonments in Analvsis
Distillation Analysis R. T.
Leslie and
E . C. Kuehner, National Bureau of Standards, Washington 25, D. C,
T
HE present revieLv covers the period from 1960 to 1962. The two preceding biennial reviews of distillation analysis began with reference to the importance of gas-liquid chromatography because of its great resolving power. I n the last biennium a t least two stills of very high srparating power have been described. A still with 450 transfer units (31-1) has been constructed and the possibility of constructing one equivalent to 1000 theoretical plates is predicted (26-4). If -these figures are squared (the approximate equivalence of still plates to gasliquid chromatograph plates) , the separating power of such stills becomes respectable compared to chromatography. Such complicating factors as azeotropism and thermal decomposition still remain.
LABORATORY FRACTIONAL DISTILLATION
An unusual method of analytical distillation, and one which can possibly be claimed by chromatography, is that of Eggertsen, Groennings, and Holst (%A). Samples of a few milligrams of 50R
ANALYTICAL CHEMISTRY
petroleum distillate are srparated into constituents by passing the material through a gas-liquid chromatograph column with a stationary phase which separates in order of boiling points. The temperature of the column is programmed and either the retention time or the temperature of emergence can be used to determine the presence or the boiling point of a constituent by the appropriate calibration. ilnalytical results in half an hour comparable to those obtained Tvith a 20-plate still are claimed. A somewhat similar use of chromatography is the determination of the vapor pressures of constituents of a mixture by calibration with reference materials (%A). A related procedure for separating hydrocarbons has been disclosed in a patent. The mixture is adsorbed on certain organic condensation products from which the constituents can be distilled off in fractions (69il). Another unusual method for separating constituents which boil close together is reported in a German patent (4A). The distillation is done at a temperature between the melting point of the lowest
and highest melting constituents. The residue from the distillation is solid. The still with 460 transfer units which was mentioned in the introductory paragraph was 9 meters long and constructed of parallel, unpacked channels. Such stills have lower pressure drop and holdup and greater flexibility of throughput and reflux ratio than packed columns. This type of still has been described frequently in recent years (L4,S9d, 41L4,42A) and is apparently very effective. The prediction that columns equivalent to 1000 theoretical plates are possible was based on an inirestigation of a packed column over a n ide range of throughput. Such a still would be 5 meters high and would be packed x i t h long sections of very fine wire mesh (26A). Descriptions of stills with rotating members in the columns are numerous. Columns with multiple-blade rotating bands are more effective than singleblade types (34.4). A review of stills with rotating members has been published by a Russian investigator, who also tested one Kith a smooth cylindrical
