Liquid chromatography ion exchange

Anacardio, R., Cantalini, M.G., De Angelis, F., and Gentile, M., Quantification of S-carboxymethyl-(R)-cysteine in human plasma by high-performance ion-exchange liquid chromatography/atmospheric pressure ionization mass spectrometry, /. Mass Spectrom., 32, 388, 1997. 

Hanai, T., Miyazaki, R., and Kinoshita, T., Quantitative analysis of human serum albumin-drug interactions using reversed phase and ion-exchange liquid chromatography, Anal. Chim. Acta, 378, 77, 1999. 

The separation of mono-, di-, and tributyltin species in seawater by isocratic ion exchange liquid chromatography coupled to hydride generation AAS has been reported by Schulze and Lehmann [107]. Reported detection limits are 31,40, and 27 mol/1, respectively. 

Spherical porous silica gel is the easiest stationary phase material to handle however, although it is physically strong it is chemically unstable. Surface modification can expand its capability for different modes of chromatography, such as normal-phase, reversed-phase, size-exclusion, and ion-exchange liquid chromatography. These stable modifications are performed by chemical deriva-tization of the surface silanol groups. 

The selection of the counter-ion and its concentration are important for the separation of ionic compounds in reversed-phase and ion-exchange liquid chromatography. The addition of hydrophobic ions is an especially powerful method and several surfactants can be used as hydrophobic counter-ions. The theoretical column efficiency of ion-pair liquid chromatography is much better than that of an ion-exchange column, and the regeneration of a column is much faster. Thus, if we can control ion-pair liquid chromatography, we can solve a separation problem. (The important background sources in this area are listed at the end of the chapter.)... 

Ion-pair liquid chromatography can be applied to compounds separated by ion-exchange liquid chromatography, and mixtures of ionic and non-ionic compounds are easily separated. The latter separation is difficult by ion-exchange liquid chromatography. Anions can be separated by reversed-phase ion-pair liquid chromatography (Figure 4.18). 

SEC is a useful tool for monitoring enzyme reactions, as seen in Figure 4.21, where the speed of decomposition of /Mactoglobulin by a-chymotrypsin is shown. SEC is widely used for purification of proteins, but the separation is due only to the difference in molecular mass. Therefore, ion-exchange liquid chromatography is combined with SEC to improve the selectivity. 

To increase Vs, the chromatographer can increase the surface area of the stationary phase materials in normal-phase liquid chromatography, increase the stationary phase volume in reversed-phase or partition liquid chromatography, or increase the ion-exchange capacity in ion-exchange liquid chromatography. In general, if the internal diameter of a column is constant, the retention time... 

G. J. Dear, R. S. Plumb, B. C. Sweatman, P. S. Parry, A. D. Roberts, J. C. Lindon, J. K. Nicholson, and I. M. Ismail, Use of directly coupled ion-exchange liquid chromatography-mass spectrometry and liquid chromatography-nuclear magnetic resonance spectroscopy as a strategy for polar metabolite identification, J. Chro-... 

Analyses of phase boundaries reveal evidence for polymer saturation in the presence of excess protein. Phase boundaries also facilitate comparisions of the behavior of various proteins. The failure of net surface charge density as a universal parameter for protein-polyelectrolyte interaction is believed to be related to the existence of "charge patches" on the protein surface. The determination of a more realistic protein charge parameter possesses great importance, since the ionic interactions of proteins are exploited in a variety of applications, including protein purification via ion exchange liquid chromatography. 

Dear, G.J. Plumb, R.S. Sweatman, B.C. Parry, P.S. Roberts, A.D. Lindon, J.C. Nicholson, J.K. Ismail, I.M. Use of Directly Coupled Ion-exchange Liquid Chromatography-Mass Spectrometry and Liquid Chromatography-Nuclear Magnetic Resonance Spectroscopy as a Strategy for Polar Metabolite Identification, J. Chromatogr. B 748(1), 295-309 (2000). 

Chromatographic patterns and data on the identity, homogeneity, and purity can be obtained by size exclusion chromatography, reverse-phase liquid chromatography, ion-exchange liquid chromatography, affinity chromatography, or other suitable procedures. 

M. Hay and P. Mormede, Determination of catecholamines and methoxycatecholamines excretion patterns in pig and rat by ion-exchange liquid chromatography with electrochemical detection, J. Chromatogr. B, 703, 15-23 (1997). 

Zbllner, P., Zenker, A., Galanski, M., Keppler, B. K., Lindner, W. Reaction monitoring of platinum(n) complex 5 -guanosine monophosphate adduct formation by ion-exchange liquid chromatography/electrospray ionization mass spectrometry. J Mass Spectrom 2001, 36, 742-753. 

Loughlin AF, Skiles GL, Alberts DW, Schaefer WH. An ion exchange liquid chromatography/mass spectrometry method for the determination of reduced and oxidized glutathione and glutathione conjugates in hepatocytes. J Pharm Biomed Anal 2001 26 131-142. 

The coefficient of correlation between the calculated individual molecular interaction (MI) energies and the logarithmic capacity ratio indicated the contribution of individual factors to the retention. MIVW was the main contributor to the interaction in reversed-phase liquid chromatography, and MIES was the main contributor to the retention in ion-exchange liquid chromatography. Steric hindrance affected the molecular interaction in enantiomeric separation. ... 

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