Columns cation exchange

Accurately weigh about 6 g NaCl and dissolve in distilled water. Pass the solution through a well-rinsed cation exchange column (Dowex 50W) in the hydrogen form. The equivalent amount of HCl is washed from the column (in 10 column volumes) into a volumetric flask and made up to volume. Equivalent weight is the formula weight. 

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

In a different set of experiments solutions of Pu(III) or Pu(VI) in H2O (Ar saturated, pH adjusted to 7, 2 x 10-5 M in Pu) were irradiated in the ANL 60Co-y source at a position where the dose was 1 megarad/hr (Jj) 1 mM H2O2 produced/hr. Cation exchange column behavior was used in an attempt to identify Pu oxidation states, see Table III. The results obtained after an irradiation of 1 hr. were indistinguishable from the "blank", i.e. a solution not subjected to irradiation. The irradiation for a 24 hr. period failed to demonstrate a marked increase in the amount of Pu(IV) produced that could be ascribed to the effects of radiolysis. 

AE was purified from orange peels. After homogenization, precipitation with 30 - 60% (NH4)2S04 followed by dialysis, the sample was applied to a cation exchange column (CM-Sepharose CL-6B). AE binds strongly to a cation exchange column material at pH 6.8... 

In order to remove the residual PME the AE fraction was further fractionated on Mono S cation exchange column. Unlike the DEAE-Sepharose column, where PME elutes after the AE activity, the order of elution was reversed on the Mono S column (Fig. 1). The last step in the purification was a gel filtration (Sephacryl S-200) column. 

Figure 8.24 Separation of the major deoxyribonucleosides and their 5 - monophosphate deoxynucleotides on a strong cation exchange column (column one) and a reversed-phase column. The unseparated nucleosides. A, on the ion- exchange column were switched to the reversed-ptose column. Pe2dc Identification A = nucleosides, B d-CMP, C d-AMP, D - d-GJIP, E - d-CVD, P d-UKO, G THD, and H = d-AOO. (Reproduced with permission from ref. 298. Copyright Preston Publications, Inc.)...

Multiple electrodes have been used to obtain selectivity in electrochemical detection. An early example involved the separation of catecholamines from human plasma using a Vydac (The Separation Group Hesperia, CA) SCX cation exchange column eluted with phosphate-EDTA.61 A sensor array using metal oxide-modified surfaces was used with flow injection to analyze multicomponent mixtures of amino acids and sugars.62 An example of the selectivity provided by a multi-electrode system is shown in Figure 2.63... 

Figure 5 Separation of pharmaceuticals, including amines, on strong cation exchange. Column 0.46 x 15 cm Merckosorb SI-60-SCX, 5 p. Eluent 50 mM aqueous ammonium formate-10% ethanol, pH 4.8. Flow 1 ml/min. Temperature 50°C. The peaks are (1) aspirin, (2) paracetamol, (3) phenacetin, (4) caffeine, (5) phenylephrine, (6) salbutamol. (Reproduced with permission of Elsevier Science from Cox, G. B., Loscombe, C. R., Slucutt, M. J., Sugden, K., and Upheld, J. A., /. Chromatogr., 117, 269, 1976).

The polyamines putrescine, cadaverine, spermidine, and spermine, which are seen at elevated levels in some victims of cancer, were separated on a Technicon (The Technicon Company Chauncey, NY) TSM Amino Acid Analyzer packed with an 8% divinylbenzene-co-polystyrene sulfonated resin with post-column ninhydrin detection.111 Amines such as ethanolamine, noradrenaline, hexamethylene diamine, methoxytryptamine, spermine, and spermidine were separated from amino acids on a DC-4A cation exchange resin.112 A similar approach, using a Beckman Model 121M amino acid analyzer equipped with an AA-20 column, was also successful.113 A Polyamin-pak strong cation exchange column (JASCO) was eluted with a citrate buffer for the detection of putrescene, spermine, cadaverine, and 1,5-diaminohex-ane from rat thymus.114 A post-column o-phthaldehyde detection system was used. 

Togami, D. W., Poulsen, B. J., Batalao, C. W., and Rolls, W. A., Separation of carbohydrates and carbohydrate derivatives by HPLC with cation-exchange columns at high pH, BioTechniques, 10, 650, 1991. 

One attempt to overcome these disadvantages has been to use multidimensional liquid chromatography (LC) followed directly by tandem mass spectrometry to separate, fragment and identify proteins (Link et al., 1999). In this process, a denatured and reduced protein mixture is digested with a protease to create a collection of peptides (Fig. 2.6). The peptide mixture is applied to a cation exchange column and a fraction of these peptides are eluted based on charge onto a reverse-phase column. The... 

After sample loading, the cation-exchange RAM-column was placed in-line with the analytical cation-exchange column and analytes were eluted with a salt gradient. A total of 24 fractions of 4 min duration (2 mL of eluent) were transferred to the... 

Dehairs et al. [78] describe a method for the routine determination ofbarium in seawater using graphite furnace atomic absorption spectrometry. Barium is separated from major cations by collection on a cation exchange column. The barium is removed from this resin with nitric acid. Recoveries are greater than 99%. 

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