Abstract: The adsorption isotherms of 4-hydroxybenzoic acid imprinted monolith which was prepared by in situ therm-initiated polymerization were determined with the frontal analysis successfully. Adsorption isotherms of the monolith were measured at 20, 40 and 50 ℃ by using acetonitrile, tetrahydrofuran, methanol and acetonitrile containing 1%, 3%, 5% and 7%(volumn fraction) acetic acid as the mobile phase, respectively. The results show that the adsorption capacity of the monolith for the template was found to be much stronger than 2-hydroxybenzoic acid. The experimental data was fitted by Bi-Langmuir isotherm, and the saturation capacity and association constant of imprinted monolith was achieved. The content of acetic acid in the mobile phase, the nature of the organic mobile phase and the temperature showed some influence on the adsorbent ability and selectivity of the imprinted polymer. This phenomenon can be explained that the saturation capacity and association constant of 4-hydroxybenzoic acid on the binding sites was influenced by the chromatographic conditions much more significantly than 2-hydroxybenzoic acid.

Key words: Frontal analysis method, 4-Hydroxybenzoic acid, Imprinted polymer monolith, Adsorption isotherm