Ion gradient elution

Adenosine 5"-[P-thio]diphosphate tri-lithium salt [73536-95-5] M 461.1. Purified by ion-exchange chromatography on DEAE-Sephadex A-25 using gradient elution with 0.1-0.5M triethylammonium bicarbonate. [Biochem Biophys Acta 276 155 7972.]... 

Another ion profile often encountered from background ions is one in which the intensity increases or falls at a regular rate throughout the analysis. This often occurs in LC-MS during gradient elution when the ion is associated with only one component of the mobile phase. 

The HPLC system used consisted of a 30 x 2 mm Luna CN column with linear gradient elution employing two mobile phases A and B (A, 90% H2O 10% acetonitrile B, 10% H2O 90% acetonittile) with both phases containing 5 mM ammonium acetate and 0.2% formic acid. The hnear gradient commenced with 50 50 A B increasing to 100% B after 1 min of the analysis this composition was maintained for 1 min before returning to 50 50 A B after 4 min. Positive-ion ionspray (pneumatically assisted electrospray) was used to obtain mass spectra, with the spectrometer operating at a resolution of 5000. 

Diluted in neutraUzed water, separation on CIS Novapak using gradient elution using methanol and phosphate buffers at pH 7 Formation of ion pairs with cetylpyridinium chloride (CeCl) in water and extraction in butanol, separation on C8 Spherisorb using gradient of acetonitrile, methanol, CeCl/phosphate buffer... 

The popularity of reversed-phase liquid chromatography (RPC) is easily explained by its unmatched simplicity, versatility and scope [15,22,50,52,71,149,288-290]. Neutral and ionic solutes can be separated simultaneously and the rapid equilibration of the stationary phase with changes in mobile phase composition allows gradient elution techniques to be used routinely. Secondary chemical equilibria, such as ion suppression, ion-pair formation, metal complexatlon, and micelle formation are easily exploited in RPC to optimize separation selectivity and to augment changes availaple from varying the mobile phase solvent composition. Retention in RPC, at least in the accepted ideal sense, occurs by non-specific hydrophobic interactions of the solute with the... 

Figure 4.21 Exploded view of a nlcroaeBbrane suppressor and gradient elution separation of a aixture of inorgemic and organic anions by ion chromatography employing conductivity detection with a mlcromembrane suppressor.

Murren, C., Stelling, D., and Felstead, G., An improved buffer system for use in single-column gradient-elution ion-exchange chromatography of amino acids, /. Chromatogr., 115, 236, 1975. 

Wade, H. E., The fractionation of phosphate esters on ion-exchange resin by a new system of pH-gradient elution, Biochem.., 77, 534, 1960. 

Malmquist, G. and Lundell, N., Characterization of the influence of displacing salts on retention in gradient-elution ion-exchange chromatography of peptides and proteins, J. Chromatogr., 627, 107, 1992. 

Hallgren, E., Prediction of protein retention at gradient elution conditions in ion-exchange chromatography, /. Chromatogr. A, 852, 351, 1999. 

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