Dynamically coated stationary phase

Model makers named the technique solvent generated ion exchange [7] and hydrophobic chromatography with dynamically coated stationary phase [8], thereby emphasizing a dynamic ion exchange model. 

Ghaemi Y. and Wall R.A. Hydrophobic chromatography with dynamically coated stationary phases. J. Chmmatogr. 1979, 174, 51-59. 

J. Chromat., 1981, 209, 203-210). Hydrophobic quaternary ammonium ions are strongly adsorbed on silica giving a dynamically coated stationary phase. Retention may be controlled by varying the concentration or nature of the quaternary ammonium ion, changing the ionic strength or pH of the buffer, or changing the concentration or nature of the organic component. 

Y. Ghaemi and R.A. Wall, Hydrophobic Chromatography with Dynamically Coated Stationary Phases, J. Chromatogr., 174 51 (1979). 

Kimura, K., Hayata, E., and Shono, T. (1984) Convenient, efficient crown ether-containing stationary phases for chromatographic separation of alkali metal ions dynamic coating of highly lipophilic crown ethers on octadecylsilanized silica, Chem. Commun., 271-272. 

M. Pawlowska, Separating anatiomers by HPLC on silica dynamically coated with a chiral stationary phase of permethylated-cyclo-dextrin, Chirality, 5 136 (1991). 

In this reversed phase high performance liquid chromatographic method for neutral and cationic metal chelates with azo dyes, tetraalkylammonium salts are added to an aqueous organic mobile phase. The tetraalkylammonium in salts are dynamically coated on the reversed stationary support. As a result of the addition of tetraalkylammonium salts, the retention of the chelates is remarkably reduced. Tetrabutylammonium bromide permits rapid separation and sensitive spectrophotometric detection of the vanadium(V) chelate with 2-(8-quinolylazo)-5-(dimethylamino)-phenol, making it possible to determine trace vanadium(V). 

When strongly hydrophobic cationic surfactants are present in the mobile phase the hydrophobic surface of the stationary phase becomes dynamically conditioned with respect to the adsorption of the surfactant. This confers an ion-exchange capability on the stationary phase. Cassidy and Elchuk (32, 33) reported use of cetylpyridinium chloride to coat the stationary phase "permanently", but used tetrabutyl and tetramethylammonium salts in the mobile phase. Their equilibration procedure also employed the use of acetonitrile in the initial conditioning step, thus increasing the overall cost of the analysis. Knox and Hartwick (36)... 

Shimbo et al. used a chiral 18-crown-6 (Figure 22-17) dynamically coated on a reversed-phase stationary phase [71, 72], This crown ether is commercially available under the trade name Crownpak CR. 

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