excitation temperature of a low level (VI = 0.966 eV) is measured, this level being much less liable to deviations from Boltzmann equilibrium than the higher excitation levels. On the other hand, it should be mentioned that the typical advantages of a null method [i.e., measurements at log (F20/ FZ1)= 01 have not been realized, However, according to Snelleman and Alkemade (3, this goal can be achieved by
means of an additional calibrated attenuation filter placed in front of the excitation source. This filter, by suitably modifying the ratio E A ~ ~ / E would A ~ ~permit , the realization of low color temperatures with high real source temperatures,
(5) W. Snelleman and C . Th. J. Alkemade, Utrecht University, Utrecht, The Netherlands, personal communication, 1972.
for review January 3 1 3 1972. Accepted 1972. Research supported by AF-AFOSR-70-1880C.
18,
~
Combined Ion Exchange-Solvent Extraction (CIESE) Studies of Metal Ions on Ion Exchange Papers Synergistic Effects and Chromatographic Separations Ani1 K. De and Chitta R. Bhattacharyya Department of Chemistry, Visva-Bharati, Santiniketan, West Bengal, India
THECONCEPT OF combined ion exchange-solvent extraction (CIESE) was introduced by Korkisch and collaborators (1). Literature reports on combined ion exchange-solvent extraction (CIESE) studies of metal ions using mixed aqueous organic solvents have pointed out greatly increased selectivities (2-18) of the technique. In our previous papers (8, 9), we have described the use of 2-thenoyltrifluoroacetone, tri-n-butyl phosphate, acetyl acetone, methyl ethyl ketone, and methyl isobutyl ketone for the CIESE separation of many metal ion mixtures generally associated with ores and minerals. In this paper, SA-2 and SB-2 ion exchange papers have been used to describe several selected chromatographic systems. No such work has yet been reported. EXPERIMENTAL Amberlite SA-2 (H+ form) and SB-2 (Cl- form) ion exchange paper strips (25 cm X 2.5 cm.) (H. Reeve Angel Co.,
Clifton, N. J.) have been used. The former contains Amberlite IR-120 sulfonic acid cation exchange resin and the latter contains IRA-400 quaternary ammonium anion exchange resin. 2-Thenoyltrifluoroacetone (TTA) (Columbia Organic Chemicals, Columbia, S. C.,) and tri-n-butyl phosphate (TBP) (Matheson Coleman & Bell Company, Rutherford, N. J.) have been used throughout the work. Initial zones of the solutions (containing 1 mg of each metal per milliliter of the solution) were spotted with fine glass capillaries and the chromatographic runs were carried out in 30-cm X 5-cm glass jars by ascending paper chromatography technique. The developed zones were quite well defined, development being carried out by spraying with suitable reagents as follows: (1) Trisodium pentacyano aminoferrate rubeanic acid : Mn (light blue), Fe(II1) (deep blue), Co (yellowish brown), Ni(I1) (blue), Cu(1I) (apple green), Zn (red); (2) Alizarin Red S : La(II1) (brown), Ce(IV) (violet), Zr(IV) (red), Th(1V) (reddish violet), In(II1) (violet), A1 (reddish violet) ; (3) KI SnClz: Pt(I1) (yellow t o brownish yellow), Pd(I1) CHsCOOH: (pink t o dark purple); (4) K4Fe(CN)G U(V1) (light brown), Mo(V1) (deep brown), V(V) (yellow) ; ( 5 ) K I (aqueous): TI(1) (yellow); (6) Oxine: Nb(V) (pink), Ta(V) (brown); (7) NH4SCN SnClz: Cr(II1) (red), W(V1) (red); (8) Rhodamine B: Ga(II1) (red); (9) Dithizone: Z n (red), C d (purple), Hg(I1) (pink), As(II1) (yellow), Sb(II1) (red), Bi(II1) (purple). Before spraying with reagents Numbers 1 and 9, the papers were exposed t o ammonia vapor. The paper after spraying with reagent number 2 was exposed to ammonia vapor.
+
+
(1) J. Korkisch and S . S . Ahluwalia, ANAL.CHEM.,38,497 (1966). (2) J. Korkisch, Progr. Nucl. Energy Ser. I X , 6, 1 (1966). (3) K. Korkisch, Separ. Sci., 1, 159 (1966). (4) J. Sherma, Talanta, 11, 1371 (1964). (5) J. Korkisch, Separ. Sci.,1, 154 (1966). (6) J. Sherma, Chemist-Analyst, 55, 86 (1966). (7) J. Sherma and K. M. Rich, J. Chromatogr., 26 327 (1967). (8) A. K. De, S . K. Sarkar, and C. R. Bhattacharya, Ind. J . Chem., in press. (9) A. K. De and C. R. Bhattacharya, Anal. Chim.(Warsaw)(communicated). (10) J. Korkisch and S. S. Ahluwalia, Anal. Chim. Acta, 34, 308 ( 1966). (11) J. Korkisch, Nature, 210, 626 (1966). (12) J. Korkisch and K. A. Orlandini, ANAL.CHEM.,40, 1127 (1968). (13) J. Musich, K. A. Orlandini, and J. Korkisch, U.S. At. Energy Comm. Rept. ANL, January 1968. (14) K. A. Orlandini and J. Korkisch, Separ. Sci., 3, 255 (1968). (15) J. Korkisch and K. A. Orlandini, Talanta, 16,45 (1969). (16) J. Korkisch and K. A. Orlandini, ANAL.CHEM.,40, 1952 (1968). (17) K. A. Orlandini and J. Korkisch, Anal. Chim. Acta, 43, 459 (1968). (18) W. Wahlgren, K. A. Orlandini, and J. Korkisch, ibid., 52, 551 (1970) 1686
+
+
RESULTS AND DISCUSSION Cation Exchange Systems. SEPARATION OF METALIONS. The separations of several metal ion mixtures are summarized in Table I, the metal ions being arranged in order of increasing atomic numbers. A combination of 0.10M solution of TTA in acetone with 6 N hydrochloric acid has been used as the developing solvent. A variation in TT4 concentration (90 to 70%) and hydrochloric acid (10 to 30%) has been found sufficient for the effective separations. A 0.1M TTA solution in acetone mixed with 6 N aqueous hydrochloric acid
ANALYTICAL CHEMISTRY, VOL. 44, NO. 9,AUGUST 1972
Table I. Rf Values of Metal Ions on SA-2 Paper Time of development: 1hour Solvent system Separation achieved metal ion mixtures 0,10MTTA:HC1(6N) 1. Mn (0.22), Fe (l.O), Co (0.42), = 8.0:2.0 (VjV) Ni (0.06), Cu (0.66), Zn (0.80); 2. A1 (0.76), Cr (0.87), Fe (1.0); 3. V (0.16), Cr (0.80), Fe (1.0) 4. Nb (0.48), Ce (0.60), La (0.74); 5. As (0.80), Sb (0.63), Bi (0.72). 6. Zr (0.00), Ce (0.43), Th (0.64); 0.10M TTA:HC1(6N) = 9.0:l.O 7. Zn (0.72), Cd (0.88), Hg (1.0). O.lOMTTA:HC1(6N) 8. V (0.20), Nb (0.59), Ta (0.86). = 7.0:3.0
Table 111. Separation of Metal Ions of Mn-Bronze Alloy (Bureau of Analyzed Samples No. 10e) on SA-2 Paper Solvent system: 0.05MTTA in acetone:HC1(6N) = 9.0 :1.0 (V/V) Time of development = 35 minutes Metal ions Fe Cu Zn Mn Ni A1 Ri 0.90 0.80 0.86 0.39 0.00 0.47 Table IV. Rf Values of Metal Ions on SB-2 Paper Solvent system: 0.10M TTA:HCl(6N):LiCI(SM) = 8.0: 1.0: 1.0 (V/V) Metal ions R, Metal ions Rf Metal ions R, Ag 0.93 As 0.55 Zr 0.42 Hg(1) 0.04 Bi 1.0 Th 0.16 W) 0.00 Sb 0.13 Ce(1V) 0.13 Zn 0.04 Cr 0.70 Sn(1V) 0.10 Cd 1.0 Ga 0.98 Pt 0.12 Hg(I1) 0.83 Ce(II1) 0.20 Nb 0.43 Uo2(II) 0.02 In 0.90 Ta 0.70 Ca 0.88 Tl(II1) 0.20 W 0.68 A1 0.58 Mo 0.60 Mn 0.95 Pb 0.93 La 0.77 Pd 0.04 Sn(I1) 0.10
Table 11. Synergistic Effects in CIESE Using 0.10M TTA0.10M TBP System at Constant 10% 6 N Overall Acidity Solvent system TTA :TBP
cu
9.0:0.00
8.0:1.00 7.0:2.00
0.69 0.62 0.62
6.0:3.00
0.60
5.0:4.00 4.0:5.00 3.0:6.00 2.00:7.00 1.0:8.00
0.68 0.74 0.71 0.68 0.65 0.63
0.00:9.00
Rf co
0.48 0.36 0.38 0.40 0.50 0.50 0.52 0.54 0.50 0.42
Table V. Separation of Different Valency States on SB-2 Paper Solvent system: TTA(O.lOM):HC1(6N):LiCI(5M) = 7.0:1.0:2.0 ( V R ) Time of development: 1hour
in the ratio 8:2 by volume has been used to separate La-CeNb, As-Sb-Bi, Fe-Al-Cr, Fe-Zn-Cu-Co-Mn-Ni, Fe-Cr-V. The metal ions in the mixtures Ce-Zr-Th, Zn-Cd-Hg(1I) have been separated with the solvents mixed in the ratio 9:1, and V-Nb-Ta in the ratio 7:3 by volume. Combined ion exchange properties of the resin in the papers and the solvent extraction properties of TTA are responsible for these metal ion separations. SYNERGISTIC EFFECT. Table I1 shows the synergistic behavior of the TTA-TBP mixed solvent system in CIESE using SA-2 cation exchange papers. The mixture of TTA (a chelating agent) and TBP (a solvating solvent) exhibits synergistic solvent extraction properties. This property is combined with the ion exchange properties of SA-2 paper for the selective separation of metal ions. Keeping the overall acidity of the mixture at 0.6N, the relative concentration of TTA and TBP are varied such that the total number of moles of TTA and TBP in the mixture remains the same. The increases in the individual Rf values from 0.60 (TTA:TBP = 6:3) to 0.74 (TTA:TBP = 4:5) in case of copper and 0.36 (TTA:TBP = 8 : l ) to 0.54 (TTA:TBP = 2:7) in case of cobalt indicate synergistic effect. This synergistic effect can be used with equally good results in ion exchange column separation. APPLICATION TO MN-BRONZE ALLOY. Table 111 shows the application of the above procedure to separations of the constituents of manganese-bronze alloy (Bureau of Analyzed Samples No. 10e) on SA-2 paper. A combination of 0.05M TTA in acetone and 6N hydrochloric acid in the ratio 9:l by volume has been used as the developing solvent, the time of development being 35 minutes only. This provides a rapid method .for the detection and qualitative separation of the metal ions present in the alloy.
Metal ion separated Ce (111), Ce (IV Sn (W, Sn (IV) T1 (I), T1 (111) Hg (11) Hg (11,
Rl
0.40, 0.15, 0.00,
0.00,
0.05 0.00
0.34 0.85
Table VI. Separation of Metal Ion in Alloy Steel Sample (Bureau of Analyzed Samples No. 64a) on SB-2 Paper Solvent system: TTA(O.lOM):HC1(6N):LiCI(5M) = 8.0: 1.0: l.O(V/V)
Metal ions
Rj
Time of development: 1hour. Cr V W 0.70 0.43 0.62
Fe 1.0
Anion Exchange Systems. Table IV gives the Rj values of the metal ions on SB-2 anion exchange paper using TTALiC1-HC1 mixed aqueous-organic solvent system. Cd, Bi move with the solvent fronts and Hg(I), Zn, Pd(II), and UO:! (11) remain at the origin of the spot. An examination of the R, values of the different metal ions suggests that one metal ion can be separated from several other metal ions. Thus Bi or Cd can be separated from Sb(III), Ce(IV), Al, Ce(III), TI(I), Zr, Th, Pt(IV), Sn(IV), V, Mo, Hg(I), and Zn. These separations may also be carried out in anion exchange column using the technique of CIESE. SEPARATIONS OF METALSIN DIFFERENT OXIDATION STATES. Several oxidation states of the same metal such as Ce(II1, IV), Sn(I1, IV), Tl(1, 111), and Hg(1,II) have been separated on SB-2 paper (Table V) using a solvent composition of 0.01M TTA in acetone, 6N hydrochloric acid, and 5M lithium chloride mixed in the ratio 7.0:1.0:2.0 by volume. In case of Tl(1) and Tl(III), separation is rather easy as the precipitation of
ANALYTICAL CHEMISTRY, VOL. 44, NO. 9, AUGUST 1972
1687
Tl(I) Occurs in chloride m.dum. Ce(III) and Ce(IV) are well separated, whereas Sn(I1) and W I V ) do not differ much in their R, values. APPLICATION TO ALLOYSTEEL. An attempt has been made to detect and separate different metal ions present in a standard alloy steel (Bureau of Analyzed Samples No. 64a). Standard solution of alloy steel sample was chiomatographed (Table VI) using a solvent system containing TTA, LiCI, and HCI. The constituents Cr, V, W, and Fe could be separated in one hour. Since the spots can be eluted with appro-
priate reagents, separation can be followed by quantitative spectrophotometric determination. This method can be fruitfully utilized for ready column separation, All the chromatographic data (Tables I to VI) seem to indicate higher selectivities which may be due to both ion exchange and partition mechanism of CIESE ( I ) . RECEIVED for review March 9, 1971. Accepted June 1 1 , 1971. The authors thank the Council of Scientific and Industrial Research, New Delhi, for awarding a Junior Research Fellowship to one of the authors (CRB).
Quantitative Determination of Olefinic Unsaturation by Measurement of Ozone Absorption Martino M. Smits and Dirk Hoefman KoninkIijkelShell-Laboratorium,Amsterdam (Shell Research N . V.), The Netherlands MANYANALYTICAL TECHNIQUES exist for the determination of olefinic unsaturation. Most chemical methods used for this purpose are based on addition reactions to the double bond. An attractive titrimetric reagent for olefins is ozone, although of course many others are available. Ozone attack on ethylenic bonds is fast and fairly selective; no substitution takes place. In ozonolysis, the double bond is cleaved and fragments are formed of different nature, depending on the reaction conditions. As one mole of ozone adds quantitatively to one equivalent of double bond, the olefin content of a given sample can be calculated directly from the ozone consumption. Several analytical methods, varying in experimental details, are based on ozonization ( I , 2). The present paper describes a modification which is claimed to have advantages in speed and convenience over the other methods. As will be shown by the results, it is accurate and widely applicable. The procedure is as follows. A mixture of oxygen and ozone of constant composition is passed at constant flow rate through the sample solution, to which a colored indicator has been added. Immediately after the ozone has converted the olefins present, the color of the indicator changes, marking the end point of the analysis. The olefin content of the sample is then calculated by comparing the reaction time with that required by a calibration standard compound. The flow rate is controlled by a precision valve and a rotameter. Ozone is supplied by a commercial “dry” ozone generator, which has a very constant output. A potential source of error is the end-point detection. Visual observation of the fading of the indicator is subjective and, in colored samples, often difficult. Besides, it requires very close attention from the analyst. For this reason, we now use a photometric device with recorder. The reaction vessel is placed between a light source and a photocell. The absorption of the solution drops rapidly during discoloration of the indicator, resulting in a change in resistance of the photocell, which is recorded continuously. With the curve thus ob( 1 ) H. Boer and E. C. Kooyman, A d . Chim.Acta, 5, 550 (1951). (2) K. F. Guenther, G . Sosnovsky. and R . Brunier, ANAL.CHEM., 36, 2508 (1964). 1688
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ANALYTICAL CHEMISTRY, VOL. 44,
I b
Figure 1. Assembly of apparatus for ozonolysis tained, the time required for the ozonolysis can be defined accurately. EXPERIMENTAL
Apparatus. The ozonolysis equipment is assembled as shown in Figure 1 and consists of the following parts: (a) A high-pressure flow regulator (Brooks Instrument Division, Emerson Electric Co., Hatfield, Pa. 19440). (b) The ozone generator with built-in rotameter(c). A suitable instrument is that manufactured by “Fischer Labortechnik” (53 BonnBad Godesberg, Heerstrasse 35-37, Germany). On the front panel a calibration curve is sketched, giving ozone output in grams per hour rs. oxygen flow in liters per hour. As ozone is highly toxic and may cause severe irritation of the respiratory tract and the eyes, the instrument should be placed under a well-ventilated fume hood. (4 The reaction vessel, consisting of two parts connected by ground-glass joints held in position by springs. ( e ) The stirrer, bell-shaped in order to ensure thorough mixing of gas and liquid. It rotates at approximately 1200 rpm. Figure 2 shows the photometric circuit. Light source El and light-dependent resistor (LDR) R1both belong to a photoelectric relay (N.V. Instrumentenfabriek H. M. Smitt, Mid-
NO. 9, A U G U S T 1972
