Cation-exchange separation metals

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. 

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). 

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. 3-152. 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+.

Aluminium and other cations can be sorbed on cation exchangers, whereas phosphate and other interfering anions are eluted. The anionic fluoride and sulphosalicylate complexes of A1 can be separated by cation exchangers from metals that do not form the corresponding complexes. 

J. S. Fritz and B. B. Garralda, Cation exchange separation of metal ions with hydrobromic acid. Anal. Chem. 34,102,1962. 

J. S. Fritz and L. H. Dahmer, Cation exchange separation of molybdenum, tungsten, niobium and tantalum fiom other metals, Anal Chem., 37,1272,1965. 

S. Fritz and J. E. Abbink, Cation exchange separation of vanadium from metal ions. Anal. Chem., 34,1080,1962. 

Figure 4.40 Separation of aikaiine-earth metals on a sulfonated silica-based cation exchanger. Separator column Nucleosil 5 SA eluent 3.5 mmol/L oxalic acid -I- 2.5 mmol/L ethylenediamine -l-50mL/L acetone, pH 4 ...

Figure 10.7 Separation of small amounts of ammonium in the presence of alkali and alkaline-earth metals in drinking water on a high-capadty weak acid cation exchanger. Separator column lonPac CS16 column dimensions 250 mm X 5 mm i.d. column temperature ...

Dowex 50W-X8 1.7 0.80 Strongly acidic cation exchanger with S-DVB matrix for separation of amino acids, metal cations, and cations. Molecular weight exclusion is <1000. 100-200 mesh is standard for analytical applications. 

Dowex 50W-X12 2.1 0.85 Strongly acidic cation exchanger with S-DVB matrix used primarily for metal separations. 

The applicability of induced pH gradients for separation of metal ions within anion- and cation-exchange columns was verified. 

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

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