Influence of the concentration of adsorbate and modifier in the mobile phase on retention in high-performance liquid chromatography

• Published in: Journal of Chromatography A 1998-02, Vol.797 (1-2), p.3-9
• Main Authors: Lanin, S.N, Ledenkova, M.Yu, Nikitin, Yu.S
• Format: Article
• Language: English
• Subjects: Anisole
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(97)01206-5

A method for the determination of the monomolecular adsorption constants from binary (adsorbate–eluent) solution directly from chromatography data (retention volume and concentration) is suggested. The constants of the adsorption equation are calculated from an anisole chromatogram measured on hydroxylated silica using n-hexane in the low concentration region. The adsorption isotherm of anisole is constructed. Good agreement between isotherms calculated by the suggested and by Glueckauf's methods is shown. The influence of the modifier concentration on retention of benzene derivatives is studied for the chromatographic system: n-hexane–tetrahydrofuran–aminopropyl silica. The deviation from linear dependence of the reciprocal of the retention volume on mole fraction of the polar modifier is explained by molecular modifier–modifier interaction in eluent. Taking into account this interaction and using the quasi-chemical model of retention allows one to describe the dependence of chromatographic data of benzene derivatives on the modifier concentration in the eluent.