| Anotácia | Two kinds of retention models describing a behaviour of ionogenic substances in reversed-phase chromatographic systems were compared. Model A utilises a concept of limiting retention factors and is especially suitable for the prediction of retention of compounds co-existing in several forms in mobile phase. An effect of the concentration of organic modifier (e.g., methanol) on the magnitudes of the limiting retention factors and equilibrium constants (dissociation constants of the separated substances) can be expressed with the aid of various, more or less sophisticated, relationships. A stoichiometric displacement model (model B) in its original form simply relates the analyte retention to the content of organic modifier in the mobile phase. In this work, it was modified to also express an effect of the mobile phase pH introducing side equilibria (acid-base) into the model. Both models predict a sigmoidal dependence of the analyte retention factor on the mobile phase pH in accordance with experimental data, and allow among others, to estimate dissociation constants from those data. Experimental dependencies between the analyte retention and the concentration of methanol in the mobile phase comply well with model A, whereas the stoichiometric displacement model could be used only in a limited range of the methanol concentrations. (C) 1999 Elsevier Science B.V. All rights reserved.
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GAGLIARDI, Leonardo G. - CASTELLS, Cecilia B. - RAFOLS, Clara - ROSES, Marti - BOSCH, Elisabeth. Modeling retention and selectivity as a function of pH and column temperature in liquid chromatography. In Analytical chemistry. ISSN 0003-2700, 2006, vol. 78, no. 16, pp. 5858-5867.
GAGLIARDI, LG - CASTELLS, CB - RAFOLS, C - ROSES, M - BOSCH, E. Effect of temperature on the chromatographic retention of ionizable compounds II. Acetonitrile-water mobile phases. In Journal of Chromatography A. ISSN 0021-9673, 2005, vol. 1077, no. 2, pp. 159-169.
BARANOWSKA, I. - ZYDRON, M. Effect of mobile-phase pH on the chromatographic behavior of biogenic amine neurotransmitters and their metabolites. In JPC : Journal of planar chromatography - modern TLC. ISSN 0933-4173, 2004, vol. 17, no. 4, pp. 297-299.
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