Cation exchange columns separation

Ion Exchange Chromatography—Separation mode for ionized compounds on charged columns. Anion-exchange columns attract and separate anions cation-exchange columns separate cations. 

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

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... 

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%. 

Ash the tissue and extract the residue with HC1 solution. Separate Ca, Mg and Zn by retention on a cation exchange column followed by elution with HC1 (5 mol dnr3). Titrate Ca using murexide, Ca plus Mg using eriochrome black T, then add chloral hydrate to give a further end point with Zn. 

The analysis time for protein hydrolysates is 85 min using standard columns. For extra high resolution a high-resolution lithium cation exchange column is recommended which achieves baseline separation of virtually all 40 amino acids (Fig. 1.3). 

In this group, Lj and L2 represent symmetrical terdentate ligands, which may be identical. The main product from the reaction of [Co(NH3)5Cl]Cl2 with dien is the s-fac Co(dien) + isomer 5 a. On heating solutions of this isomer for long times, small quantities of the other isomeric forms, u-fac and mer, result, 5b, and c (R, =R2=H). Separation of the three forms is carried out by using Sephadex cation exchange columns. Characterization of the isomers is possible by nmr which together with absorption spectroscopy, is used to study the interconversions. 

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