titration of cadmium and zinc using naphthyl azoxine indicator by comparing the visual end point n ith the stoichiometric end point obtained by photometric titration a t 440 mp. With one observer the visual and photometric end points were found t o differ by 0.02 nil. in a 6.0-ml. titration. This error is cancelled by taking the same end point color for both standardization and for actual saniplcs, providing that about the same volume of titrant IS used for each. However. the existence of this error should be rwilled nhen changing from oiic rhelomctric indicator to another. LITERATURE CITED
(1) Xsit, IC. It., S c i . and Culture 19, 568 1 1951). (2) Assoc. Offic. Agr. Chemists, Washington, D. C., "hlethgds of Analysis," 7th ed., p. 758, 1950. (3) Barcza, L., Acta Pharni. Hung. 25, 102 (1955). (4) Blaedel, W.J., Knight, H. T., -4x.k~. CHEM.26.741 il954i. ( 5 ) Brandybpadhayay; D., Sei. and Culture 20, 146 (1954).
( 6 ) Budesinsky, B., Cheni. listy 49, 1726
(1955). ( 7 ) Chena. K. L., ASAL. CHEM.27, 1582 ' (1955).(8) Cheng, K. L., Kurtz, T., Bray, R. H., Zbid., 24, 1640 (1952). (9) Courtney, R. C., Gustafson, R. L., Chaberek, S., Jr., Martell, A. E., J . Anz. Chem. Soc. 80, 2121 (1958). 110) Flaschka. H.. Mikrocheniie z'er. fiikrochim. Acta 39, 38 (1952). (11) Flaschka, H., Hrtditz, F., Ruder Rundschuu 1952, 181. (12) Fritz, J. S., Lane, W. J., Bystroff, 4. S.,A K A L . CHEhf. 29, 821 (1957).-. (13) Hall, J. L., Gibson, J. .A,, Jr., I T ilkinson, P. R., Phillips, H. O., Z3id., 25, 1483 (1954). (14) Hoffmann, 0. F. h.; Q ~ t i n z . ind. (Montevideo) 2, 210 11952). (15) Jones, S. S., Long, F. A., J . Phys. Chem. 56, 25 (1952). (16) Keywort,h, D. A , , Hahn, R. B., AXAL.CHEM.30, 1343 (1958). (17) Lheureux, M.,Henri, S., Haniset, P., Ind. chim. belge. 21, 695 (1956). (18) Lott, P. F., Cheng, K. L., Chemist Analyst 4 7 , s (1958). (19) Malat, ll., Suk, \-., Ryba, O., Collection Cmchoslov. Cheni. Conimuns. 19, 258 (1954). (20) llalinek, AI,, Rehak, B., Chem. lisly 49, 765 (1955). (21) llilner, G. IT. C., Barnett, G. h.,
Atomic Energy Research Establ. (Gt. Brit.) C/R 1865 (1956). (22) Milner, G. W. C., Woodhead, J. L., Ibid., C/R 1400 (1954). ( 2 3 ) Naumann, C. K., Chenz. Yech (Berlin) 6. 545 119541. (24) Povikl1,'J. E.,'Hiller, M. A., ,I. Chem. Educ. 34, 330 11957). (25) Pribil, R.. Koudela, Z., llntyska, B., Cheni. listy 44, 222 (1950). 126) Saito, K., Terrev. H., J . C'heni. Soc. 1956, 4701. ( 2 7 ) Schw arzenhach, G., "Die Komplexometrische Titration," Ferdinand Enke, Stuttgart, Germany, 1955. (28) Shead, -4. C , A\xk~,.CHEJI.24, 1451 (1952). (29) Smirnov-Avern. -1 P., Krot, S . S . , Sokolov. A . B., J .Inal. Chem l'.S.S.R. 13,280 (1958): 1:30) Smith, G. F., Kilkins. I). H.. d n a l . C h l ' ? ~Acta . 8 , 209 (1953). (31) U. S. Atomic Energy Conim., Rept. ISC-596 (1955). (32) I'restal, J., Havir, J., Branstetr, J., Kotrly, P.,Chem. listy 51, 2033 (1951). (33) Wagner, I\*. F., Wuellner, J. .4., Feiler, C. E., ANAL. CHEX 24, 1491 (1952). RECEIVEDfor review May 11, 1959. Accepted A-lpril 13, 1960. Contribution KO. 750. Work performed i n Ames Laborstoy of thi. P.8. Atomic Energy Coninnssion.
Ion Exchange Separation of Metal Cations JAMES S. FRITZ and SHIRLEY K. KARRAKER lnstifufe for Atomic Research and Department o f Chemistry, Iowa State University, Ames, Iowa
)Metal cations can b e conveniently separated into groups by elution of a cation exchange column with an ethylenediammonium perchlorate solution. Most divalent ions are eluted from the column with 0.1M eluent. Then trivalent metal ions (plus barium and lead) are eluted with 0.5M ethylenediammonium perchlorate. Bismuth, thorium, and zirconium remain quantitatively on the column after this treatment. The effect of temperature and of certain complexing anions on the separations was studied.
T
affinity of ion exchange resins for metal cations increases appreciably as the csharge on the ion increases. Other factors such as the hydrated ionic radius also affect the uptake of a givcn ion by the resin ( 4 ) . Differences in affinity of a n ion exchange column for various metal ions can he made the basis of n chromatographic separat'ion. In gcneral, ions of different charge can bc separated rather easily; ions of like charge usually require a much longer elution. I n most separations of this type hydrochloric acid has been used :is the eluting agent ( 2 , 11, 23, 16). I n a recent paper, the authors re-
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Figure 1. Elution of metal ions from 8-cm. column with 0.1M ethylenediammonium perchlorate
-Room temperoture - - - 70' C.
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ported the cahroniatographic scparation of lanthanum and zinc using a n ethylenediammonium salt as the eluting agent (6). In this paper, the elution of a number of di-, tri->and quadrivalent
metal ions is discussed. By elution with a solution of a n ethylenediammonium salt, most of the ions studied can he conveniently separated into groups according to charge. VOL. 32, NO. 8, JULY 1960
957
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Figure 3. Elution o f metal ions from 8-cm. column with 0.5M ethylenediammonium perchlorate at room temperature
EXPERIMENTAL
The most essential experimental details are given below. Additional details have been published (6). Ion Exchange Resin. Dowex 50XS or Dowes 50W-X8, 100 t o 200 mesh, in t h e ethylenediammonium form. Ion Exchange Column. Fill conventional ion exchange columns 12 mm. in inside diameter with resin t o a height of 8 or 16 cm. For work a t elevated temperatures, use a column 12 mm. in inside diameter, surrounded bv a condenser-type jacket, through t
