Cation exchange separations

Another material based on the crown ether extractant 4,4 (5 )-bis(t-butyl-cyclohexano)-18 crown-6, marketed under the name Sr-Spec, is useful for separations involving divalent cations including Pb, Ba, and Ra (Horwitz et al. 1991). For Ra analysis by TIMS, Ra-Ba separations are required because the presence of Ba drastically decreases the ionization efficiency of fg Ra samples from 10% to <1%. This material has been widely used for separations of Ra from Ba (e.g., Chabaux et al. 1994 Lundstrom et al. 1998 Rihs et al. 2000 Joannon and Pin 2001 Pietruszka et al. 2002) and is a complement or alternative to cation exchange separations for EDTA complexes of these elements (Volpe et al. 1991 Cohen and O Nions 1991). Sr-Spec material would also be useful for °Pb analysis, since Pb has a greater distribution coefficient than Sr with this extractant. 

HPLC Separation of Histamine. There are three possibilities for separation of histamine by HPLC normal phase on silica, reversed phase on a bonded silica column, or an ion-exchange separation. Perini (16) demonstrated that a cation-exchange separation is possible, but the analysis time was lengthy for examination of histamine in animal biofluids (70 min). Histamine is freely soluble in water, is slightly soluble in hot chloroform, and is insoluble in less polar solvents, making a... 

Ishii, D., Hirose, A., Hibi, K., and Iwasaki, Y., Studies on micro high-performance liquid chromatography. 5. Design of a microscale liquid chromatograph and its application to cation-exchange separation of alkali-metals. Journal of Chromatography 157(Sep), 43-50,1978. 

Parallelly, if OH ions can be added, the suppression is feasible also for cation-exchange separations. 

In Figure 26-3, an [H+l gradient was used for a cation-exchange separation. The column for this separation has nitrilotriacetic acid groups that bind lanthanide cations in the order... 

Figure 5 Analysis of selected fractions from SP column by 2-D PAGE. Fractions I through IV from the cation-exchange separation of rat serum (Fig. 4) were analyzed by 2-D PAGE. Low-abundance proteins enriched by fractionation are noted with arrowheads.

Small and co-workers [6] at Dow Chemical discovered that alkali and alkaline earth metals could be separated and determined analogously to anions with a cation exchange separation and an anion stripper now commonly known as a suppressor. With the latest developments in high efficiency columns and high capacity suppressors, it is possible to determine the common alkali and alkaline earth metals along with ammonia in a single injection run of less than 15min (Fig. 2.1). 

K. E. 0degard, W. Lund, Multi-element speciation of tea infusion using cation-exchange separation and size-exclusion chromatography in combination with inductively coupled plasma mass spectrometry, J. Anal. Atom Spectrom., 12 (1997), 403-408. 

Benker, D. E. Chattin, F. R. Collins, E. D. Knauer, J. B. Orr, P. B. Ross, R. G. Wiggins, J. T. "Chromatographic Cation Exchange Separation of Decigram Quantities of Californium and Other Transplutonium Elements", paper presented at Symposium on Industrial Scale Production-Separation-Recovery of Transplutonium Elements, 2nd Chem. Congr. North American Continent, Las Vegas, NV, 1980. 

Chromatographic Cation Exchange Separation of Decigram Quantities of Californium and Other Transplutonium Elements... 

Figure 3-26. Two-dimensional separation of tryptic digest of BSA by simple 2D-HPLC. First-D cation exchange separation (horizontal axis), MCI CQK-31S 5-mm (50 mm, 2.1-mm i.d.) column, 2nd-D reversed-phase separation (vertical axis), monolithic silica-C18 Chromolith Flash (25 mm, 4.6 mm i.d.) column. The fractionation at the Ist-D was done every 2min. (Reprinted from reference 98, with permission.)...

Fia. 15. High-resolution chromatogram of the ninhydrin-positive compounds in 0.5 ml of human urine. This was a single cation-exchange separation using step elution that required 65.5 hours. From Hamilton (HI, H3), Handbook oj Chemistry, 2nd Ed., p. B-92, with permission. 

Korkisch, J., Sorio, A. The determination of beryllium in geological and industrial materials by atomi-absorption-spectrometry after cation-exchange separation. Anal. Chim. Acta 82, 311 (1976)... 

Wheelwright has developed a cation exchange separation of americium from the lanthanides using DTPA as eluent (24). Nakamura et al. have improved the process by incorporating a porous-type cation-exchange resin and a pressurized column (25). The effect of radiation damage of the resin has been also investigated on operation modes. 

Fig. 3-132. Separation of alkali metals on a latex cation exchanger. - Separator column Fast-Sep Cation I chromatographic conditions see Fig. 3-129.

Fig. 3-134. Separation of alkaline-earth metals on a silica-based cation exchanger. - Separator column Nucleosil 5 SA eluent 0.0035 mol/L oxalic acid + 0.0025 mol/L ethylenediamine + 50 mL/L acetone, pH 4.0 flow rate 1.5 mL/min detection direct conductivity injection volume 100 pL solute concentrations 2.5 ppm magnesium, 5 ppm calcium, 20 ppm strontium, and 40 ppm barium.

Fig. 3-138. Amperometric detection of hydroxylamine after separation on a cation exchanger. -Separator column IonPac CS3 eluent 0.03 mol/L HC1 flow rate 1 mL/min detection amperome-try on a Pt working electrode oxidation potential +0.85 V injection volume 50 pL solute concentration 10 ppm.

Fig. 3-152. Separation of heavy and transition metals on a surface-sulfonated cation exchanger. -Separator column IonPac CS2 eluent 0.01 mol/L oxalic acid + 0.0075 mol/L citric acid, pH 4.2 flow rate 1 mL/min detection photometry at 520 nm after reaction with PAR injection volume 50 pL solute concentrations 5 ppm Fe3+, 0.5 ppm Cu2+, Ni2+, and Zn2+, 1 ppm Co2+, 10 ppm Pb2+, and 5 ppm Fe2+.

Fig. 3-153. Separation of heavy and transition metals on a polymethacrylate-based cation exchanger. - Separator column Sykam LCA A02 eluent 0.1 mol/L tartaric acid, pH 2.95 with NaOH flow rate 2 mL/min detection photometry at 500 nm after reaction with PAR and ZnEDTA injection volume 100 pL solute concentrations 2 ppm Fe3+ and Cu2+, 4 ppm Pb2+, 1 ppm Zn2+, 2 ppm Ni2+ and Co2+, 4 ppm Cd2+, 1.8 ppm Fe2+, 1 ppm Ca2+ and Mg2+.

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