Cation Exchange-Reversed Phase

This instrument was used to analyze mixtures of intact proteins, including protein standards and a cell lysate of the bacterium Escherichia coli. A UV 

FIGURE 8.4 2D chromatogram of a AEX x RPLC separation of reduced porcine thyro-globulin. Reprinted from Holland and Jorgenson (2000), by permission of John Wiley Sons, Ltd. 

FIGURE 8.5 2D chromatogram of a CEX x RPLC separation of an E. coli lysate. Reprinted with permission from Opiteck et al. (1997), copyright 1997, American Chemical Society. 

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Basic Cation-exchange Reversed phase ion-pair... 

Fig. 13.18 Reversed phase HPLC-ESI-MS ion chromatograms of the strong cation exchange solid phase extract of an Echium vu/gore-derived honey, (a) Total ion chromatogram, (b) base ion m/z 200-500) chromatogram, and (c)-(f) reconstructed ion chromatograms displaying m/z 414, 398, 374, and 332, respectively.

The extensive use of reversed phase ion-pair HPLC in peptides has meant that some aspects of ion-exchange HPLC are not being exploited, e.g. for peptide mapping. The isocratic separation of the two desired components from a tryptic digest of an epidermal factor fusion peptide can be achieved using a cation-exchange stationary phase in combination with a step-wise gradient of sodium chloride in... 

Leicunaite J, Klimenkovs I, Kviesis J, Zacs D, Kreismanis JP (2010) Liquid chromatography and characterization of ether-functionalized imidazoUum ionic liquids on mixed-mode reversed-phase/cation exchange stationary phase. C R Chim 13(10) 1335-1340... 

Recovery and Purification. The dalbaheptides are present in both the fermentation broth and the mycelial mass, from which they can be extracted with acetone or methanol, or by raising the pH of the harvested material, eg, to a pH of 10.5—11 for A47934 (16) (44) and A41030 (41) and actaplanin (Table 2) (28). A detailed review on the isolation of dalbaheptides has been written (14). Recovery from aqueous solution is made by ion pair (avoparcin) or butanol (teicoplanin) extraction. The described isolation schemes use ion-exchange matrices such as Dowex and Amberlite IR, acidic alumina, cross-linked polymeric adsorbents such as Diaion HP and Amberlite XAD, cation-exchange dextran gel (Sephadex), and polyamides in various sequences. Reverse-phase hplc, ion-exchange, or affinity resins may be used for further purification (14,89). 

Sugar analysis by hplc has advanced greatly as a result of the development of columns specifically designed for carbohydrate separation. These columns fall into several categories. (/) Aminopropyl-bonded siHca used in reverse-phase mode with acetonitrile—water as the eluent. (2) Ion-moderated cation-exchange resins using water as the eluent. Efficiency of these columns is enhanced at elevated temperature, ca 80—90°C. Calcium is the usual counterion for carbohydrate analysis, but lead, silver, hydrogen, sodium, and potassium are used to confer specific selectivities for mono-, di-, and... 

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.)...

Strong cationic-exchange extraction and reversed-phase extraction (eliminates ion pairing when used in place of octadecyl silica. 

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