JOURNAL OF CHEMICAL EDUCATION
INORGANIC PAPER CHROMATOGRAPHY II. Separation of Groups III, IV, and V JOHN G. SURAK, NORMAN LEFFLER, and ROBERT MARTINOVICH Marquette University, Milwaukee, %cousin
INVIEW of its ever increasing importance chromatographic analysis is being introduced to a greater extent to students of qualitative analysis as a supplement to the conventional method of analysis for the cations (1,Z, S,4,6,6). I n the preceding papers (1,4), cations of Groups I, IIa, and IIb were separated and identified by means of paper chromatography. This paper concerns itself with the separation and identification of the cations of Groups IIIa, IIIh, IV, and V. The equipment used was of the type previously reported (4). The only variation in the technique was that the ions were applied on the filter paper by means of a camel's hair brush. It was found that more uniform bands were obtained by this method than by the capillary pipet method. In the case of Groups I and 11, a single chromogenic reagent sufficed to identify the cations, namely, 0.2 per cent K2Cr04for the Ag group and Hi3 for the
Cu-Sn group. However, in the case of Groups 111and IV, individual chromogenic reagents will have to be used for the identification of the respective cations. I n the preparation of the solutions, the chlorides of the metals were used. For Group 111, the solutions were made 0.2 per cent (W/V); those of group IV were made 0.2 N. The solvents were made up on a percentage basis (V/V). The pH was determined by means of a pH meter, although Hydrion paper may he used as in the previous paper. The following technique is utilized for the determination of the bands: After the development of the chromatogram and subsequent drying for the removal of the solvent, a camel's hair brush dipped in the identifying reagent is touched along the edge of the paper in order to reveal the location of the bands. When the position is located, that area is then brushed with the reagent to bring out the entire band.
JANUARY, 1953
The ratio of the movement of the solute to that of the solvent is defined as the Rf factor. Although this is consistent for a given set of variables, such as temperature, pH, time, solvent, complexing agents, etc., it loses its usefulness as a means of identification when any of the previously mentioned variables are changed. The conditions must always be the same for any reproducibility of Rf values. Group IIIa (Aluminum Group)
TYPEOF PAPER: Whatman's Pmm. TIMEOF DEVELOPMENT: 24 hours DEVEWPING SOLVENT 70% Tertiary butyl alcohol 30% Water pH adjusted to 2 3 with HCI Rr's @ PH 3 RF's @ PH 2 Al 0.232 0.382 Zn 0.416 0.540 Cation A1 Zn
Identifyin Reagat Aurin triear%oxyliemid Dithizone in CCll
Color Light red Pink
Oroup IIIb (hon Gmup) TYPEOF PAPER: Whatman's Smm. DEVELOPING SOLVENT 87% Acetone 8% HCl(6 N ) 5% Water TIMEOF DEVELOPMENT: 3 hours Rr's Fe . . . . . . . . . . . . . . . . . .1.000 Co. . . . . . . . . . . . . . . . . .0.326 Mn . . . . . . . . . . . . . . . .0.113 Ni . . . . . . . . . . . . . . . . . .0.048
DEVEWPING SOLVENT (7) 97% Aoetone 3% HCI (6 N ) TIMEOF DEVELOPMENT: 23 hours RF'S
Cation Fe Fe Co Mn Ni
Zdatifying Reagat Potassium ferroeyanide 0.2% Nitroso-8-naphthol 0.2% Nitroso-@-naphthol 0.05% Beneidine base (standard method) 1% Alc. D~methylglyoxine
Color Blue Grayish-black Reddish-brown Blue Red-pink
Group IV (Alkaline Earth Gmup) TYPEOF PAPER: Whatman's Smm. TIMEOF DEVELOPMENT: 6-7 hours DEVELOPING SOLVENT DEVELOPING SOLVENT 40% Isopropyl alcohol 40% Isopropyl alcohol 40% Water 30% Water 20% HCI (6 N ) 30% HCl (6 N ) RF'S RF'S Ca 0.93 Cs. 0.63 Sr 0.61 Sr 0.55 Ba 0.48 Ba 0.40
Cation Ca Sr Ba
Identifying Reagent 2% Alc. alizarin 0.2% Potassium rhodizinate 0.2% Potassium rhodieinate
Color Violet Yellow-orange Red
Group V (Alkali Metals Gmup)
Group V has been separated by several investigators (7, 8, 10). S. Chakrabarti and D. P. Burma (10) suggest the following: TYPEOF PAPER: Whatman's No. 1 Neutral solution of their chlorides (1%) DEVELOPING SOLVENT DEVELOPING SOLVENT Methyl Alcohol Ethyl Alcohol-Water (7:3)
The positions of the cations are found by spraying with a mixed solution of silver nitrate and fluorescein (7) and then drying the strip. Characteristic dark bands reveal their presence. Additional work needs to be done on certain of the cations, especially in the field of identifying reagents. In the case of benzidie base for manganese, the color fades in about 5 minutes; also, the spot with the indicator must be made alkaline to bring out the color. V. Hovorka and Z. Holybecker (9) suggest the use of 2,3-butanedione oxime thiosemicarhazone as a sensitive microchemical test for manganese. A red-violet color indicates the presence of manganese when made ammaniacal. The test for calcium must be conducted in the absence of ammonia fumes as the latter will also give a violet color with alizarin. While the scheme of analysis presented in these two papers is based on the conventional qualitative analytical groups, some investigators (11) have suggested a classification of the cations into qualitative chromatographic groups based on the separation of these ions by means of specified selective solvents. LITERATURE CITED (1) FRIERSON, W. J., AND M. J. AMMONB; J. CAEMEDUC.,27, 27 1195Il~~ -. - - - - ,. (2) PAWN, A. R., Ibid., 27.60 (1950). (3) PAWN, A. R., Ibid., 27, 574 (1950). (4) SUUK, J. G., AND D. P. SCHLUETER, Ibid., 29, 144 (1952). H. H., AND L. A. TRAFTON, Ibid., 29,285 (1952). (5) FILLINGER, C. N.. AND H. E. ROGERS. Zbid., 29.404 (1952). (6) TRUMBORE. \
~. WELLS,~ a t & e(London), 163, 64 (1949).
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(8) POLLARD, F. H., J. F. W. MCOMIE,AND I. I. M. ELBEIH, J. Cham. Soc., 1951, 466. n , AND Z. HOLYBECKER, Collection Czeehoslou. (9) H o v o ~ ~ V., Chem. C m u n s . , 15, 281, No. 5-6 (1950). S., AND D. P. BURMA, Sn'ence and C U ~ T ~ (10) CEAKRABARTI, (India), 16, 485 (1951). (11) F~rEnsoa,W. J., Paper presented to Analytical Chemistry Division, 121st A. C. 5. Meeting, Buffalo, March, 1952. P
