Chromatographic separation of some alkali metals

The chromatography of the alkali metals is described using 5% 15 N NH₃ in methanol as solvent and bromophcnol blue to identify the spots. Interfering elements have been studied. The method gives a rapid and more positive method of separation and identification than previously possible.     

Quantitative analysis of monoclonal antibodies by cation-exchange chromatofocusing

A robust cation-exchange chromatofocusing method was developed for the routine analysis of a recombinant humanized monoclonal IgG antibody. We compare the chromatofocusing method to the conventional cation-exchange chromatography (CEX) employing a salt gradient and show clear advantages of chromatofocusing over CEX. We demonstrate the suitability of the present chromatofocusing method for its intended purpose by testing the validation characteristics. To our knowledge, this is the first chromatofocusing method developed for the routine analysis of monoclonal antibody charge species.     

Analytical separation of amino acids on a cation-exchange resin cross-linked with m-divinylbenzene.

The elution bands of acidic and neutral amino acids of protein hydrolysates, emerging from the column of a cation-exchange resin cross-linked with pure m-divinylbenzene, are narrower than those from a resin prepared from styrene and technical divinylbenzene. As a result of these narrower bands, a more complete resolution of the critical pairs threonine-serine, glycine-alanine and tyrosine-phenylalanine is obtained. The most probable reason for the narrower elution peaks is the more rapid diffusion of the exchanged components through the bulk of the resin as a result of a more regular arrangement of cross-linkages in the cation-exchange resin prepared from m-divinylbenzene.     

Scope,limitations and mechanism of nucleotide separation by thin-layer chromatography with strong cation-exchange resin containing layers

Summary The scope and limitations of the application of the commercially available cation-exchange thin-layer chromatoplate (Fixion 50-X8) for the resolution of nucleotide mixtures is presented. A possible separation mechanism is proposed and discussed.Publication No. 11 in the series dealing with the separation of nucleic acid bases, nucleosides and nucleotides on thin-layers consisting of strong cation-exchange resins.     

Ion chromatography on chelating stationary phases: separation of alkali metals

Analytical 250x4.6 mm I.D. columns packed with iminodiacetic acid (IDA) derivatised silica were used to separate alkali metal ions and the ammonium ion in combination with non-suppressed conductivity detection. The addition of 2.5-10 mmol/l of the macrocyclic crown ether 18-crown-6 to the nitric acid eluent resulted in a change in the elution order and a significant improvement in the resolution between potassium and ammonium because of selective complexation of potassium. However, the admixture of 15-crown-5 did not improve the resolution of lithium and sodium, although 15-crown-5 is a selective complexing agent for sodium. Retention and resolution of lithium, sodium, ammonium, cesium, rubidium and potassium ions increased at lower temperatures down to 1 degree C. The simultaneous separation of alkali and transition metals under isocratic conditions was achieved with an eluent comprising 10 mmol/l 18-crown-6, 1.5 mmol/l dipicolinic acid, and 1.9 mmol/l nitric acid. The chromatographic system enabled the quantitation of alkali metal ions with detection limits in the low ppb range and excellent linearity. Finally, the applicability of the method was approved by quantitation of sodium, ammonium and potassium in different water samples.     

Ligand sorption and chromatographic separation of metals with XAD-2 resin

Summary A macroreticular adsorbent (crosslinked copolymer of styrene and divinylbenzene) is used as the solid support. Ligands immobilized to the resin via physical forces selectively form complexes with metal ions in the solution, thus achieving separation or preconcentration. The compounds studied are sodium tetraphenylboron, 1,10-phenanthroline, 8,8(ethylenediimino)-diquinoline, 8-hydroxyquinoline and 5-chlorobenzotriazole. Since these agents possess properties of acids and bases, the pH of solution exerts great influence on the adsorption of ligands on the resin. pH-dependent studies on the distribution coefficient shows that, when conditions favor the existence of neutral species, the adsorption reaches maximum.

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Zusammenfassung Ein grobmaschiges Adsorptionsmittel (Copolymerisat aus Styrol und Divinylbenzol) wurde als feste Trägersubstanz verwendet. Daran durch physikalische Kräfte gebundene Liganden bilden selektiv Komplexe mit Metallionen in der Lösung und ermöglichen so deren Trennung oder Anreicherung. Als derartige Verbindungen wurden Bortetraphenylnatrium, 1,10-Phenanthrolin, 8,8-(Äthylendiimino)-dichinolin, 8-Hydroxychinolin und 5-Chlorbenzotriazol untersucht. Da es sich hierbei um Zwitterionenbildner handelt, hat das pH der Lösung großen Einfluß auf die Adsorption von Liganden an das Harz. Die Untersuchung der pH-Abhängigkeit des Verteilungskoeffizienten zeigt, daß die Adsorption ihr Maximum erreicht, wenn die Lösungsbedingungen die Bildung neutraler Formen begünstigen.

     

Concentration and separation of trace metals with an arsonic acid resin

Macroporeus arsonic acid resins with different pore sizes and surface areas were prepared and the properties compared. One of the resins was used for concentration of trace metal ions from dimineralized water, tap-water, and sea-water. The effect of pH and complexing agents on the recovery of metal ions was studied. A method for separation of uranium(VI) and thorium(IV) from each other and from other metal ions was developed.     

The separation of silver from mixtures by cation-exchange chromatography

Summary The cation-exchange behaviour of milligram amounts of silver on Dowex 50 W-X 8 has been studied, with nitric acid, sulphuric acid, ammonium acetate, ammonium nitrate, sodium nitrate, citric acid, tartaric acid, and acetic acid as eluents. A volume of 200–300 ml of 3M nitric acid, sulphuric acid, ammonium acetate, ammonium nitrate, or sodium nitrate was adequate for quantitative removal of 26 mg of silver from a 1.4×19 cm column of resin. Methods are described for the separation of silver from Ce, Zr, Th, Bi, and Fe by conversion of these elements into anionic complexes; from Cu, U, Al, and Zn by selective elution with nitric acid; from Ba, Sr, Sb, and As by elution with specific eluents.

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Zusammenfassung Das Verhalten von Milligrammengen Silber am Kationenaustauscher Dowex 50 W-X 8 bei Verwendung von Salpetersäure, Schwefelsäure, Ammoniumacetat, Ammoniumnitrat, Natriumnitrat, Zitronensäure, Weinsäure und Essigsäure als Eluenten wurde untersucht. 200 bis 300 ml 3-m Salpetersäure, Schwefelsäure, Ammoniumacetat, Ammoniumnitrat oder Natriumnitrat waren hinreichend für die quantitative Elution von 26 mg Silber aus einer Harzsäule von 1,4×19 cm. Methoden zur Trennung des Silbers von Ce, Zr, Th, Bi und Fe durch Überführung dieser Elemente in Komplexanionen wurden beschrieben. Die Trennung von Cu, U, Al und Zn gelingt durch selektive Elution mit Salpetersäure, von Ba, Sr, Sb und As durch Elution mit spezifischen Eluenten.

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Résumé On a étudié le comportement de quantités d'argent de l'ordre du milligramme du point de vue échange cationique sur Dowex 50 W-X 8, avec différents éluants: acide nitrique, acide sulfurique, acétate d'ammonium, nitrate d'ammonium, nitrate de sodium, acide citrique, acide tartrique et acide acétique. Un volume de 200–300 ml d'acide nitrique 3M, d'acide sulfurique, d'acétate d'ammonium, de nitrate d'ammonium ou de nitrate de sodium est nécessaire pour l'élimination quantitative de 26 mg d'argent d'une colonne en résine de 1,4×19 cm. On décrit des méthodes de séparation de l'argent d'avec Ce, Zr, Th, Bi et Fe par conversion de ces éléments en complexes anioniques; d'avec Cu, U, Al et Zn par élution sélective par l'acide nitrique; d'avec Ba, Sr, Sb et As par élution avec des éluants spécifiques.

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We wish to thank Dr.R. A. Chalmers for helpful discussion and suggestions.     

A group separation based on anion- and cation-exchange from hydrofluoric acid medium Application to multielement neutron-activation analysis of niobium

A group separation procedure for the determination of 33 elements has been developed and applied to the neutron-activation analysis of niobium. It is based on cation- and anion-exchange chromatography in HF media and separates the elements into five groups suitable for gamma spectrometry. The recoveries and their reproducibilities have been studied by the radiotracer technique. Recovery 95% (mean deviation 3%) was obtained for all the elements tested. For a 12-hr irradiation at a thermal neutron flux of 8 x 10(13) n.cm(-2).sec(-1), the limits of detection for a niobium matrix vary between 0.6 pg (for Mn) and 0.6 mug (for Fe).     

Separation of selenite,sulkate and iron by cation-exchange resin

Selenite, sulfate and iron(III) are separated by cation-exchange resin. Microgram amounts of selenite in iron(III) sulfate solution at pH 2 are completely adsorbed on the resin together with the large excess of iron(III). while sulfate passes through. Selenite is eluted with 0.5 N hydrochloric acid, leaving iron(III) in the resin. The procedure is applied to the determination of these elements in natural iron sulfides.     

Quantitative separation of calcium from magnesium,aluminium, iron(III) and many other elements by cation-exchange chromatography in methanolic hydrochloric acid on a macroporous resin

Calcium can be separated from Mg, Al, Cu(II), Fe(III), Ga, Zn, Mn(II), Co(II), U(VI) and Ti(IV) by cation-exchange chromatography on a column of AG MP-50 macroporous resin. Sr, Ba, Sc, Y, the lanthanides, Zr, Hf and Th are retained together with calcium. The separation factor for the Ca—Mg pair in 3 M HCl containing 50% methanol is about 20 which is considerably larger than those obtained by other ion-exchange procedures. Separations with the cation-exchange resin are sharp and quantitative. A column containing only 2 g (5.4ml) of resin is sufficient to separate up to 0.2 mmol of calcium from 2 mmol of magnesium and larger amounts of Fe(III), Cu(II) and Zn. On a 10-g column, up to 2.5 mmol of calcium can be separated easily from similar and larger amounts of other elements. Distribution coefficients for calcium and magnesium with variation of cross-linkage and variation of methanol concentration are presented, together with relevant elution curves and results for synthetic mixtures.     

Quantitative separation of lanthanides and scandium from barium,strontium and other elements by cation-exchange chromatography in nitric acid

The lanthanides plus yttrium and scandium are separated from Ba, Sr, Ca, Mg, Pb(II), Bi(III), Zn, Mn(II) and U(VI) by eluting these elements with 2.0 M nitric acid from a column of AG50W-X8 cation exchange resin (200-400 mesh). The lanthanides are retained and can then be eluted with 4 M nitric or hydrochloric acid. Separations are quantitative and applicable to microgram and millimolar amounts of the lanthanides and the other elements. Elements such as Cu(II), Co(II), Ni(II), Cd. Hg(II), T1(I). Ag, Be, Ti(IV) and the alkali metals should accompany barium quantitatively according to their known distribution coefficients. Relevant elution curves and results of analysis of synthetic mixtures are presented.