Chitosan membrane was prepared, and dielectric measurement was carried out on two measuring systems: one is the chitosan membrane immersed in salicylic acid aqueous solution and the other is the chitosan membrane with adsorbed salicylic acid immersed in distilled water.Dielectric relaxations were found for both membrane/liquid systems centering round the frequencies 100～700 kHz, and the character parameters of the dielectric spectra varied with the time of the membrane immersed in the corresponding liquid phase.The dielectric spectra were analyzed using the formula based on the Maxwell-Wagner interfacial polarization theory, and time dependence of the electric parameters, permittivity and conductivity, of the two constituted phases, was obtained.By analyzing the variation of the conductivity of the two phases, it was found that the chitosan membrane gradually adsorbed the salicylic acid in the solution, and the membrane with adsorbed salicylic acid slowly released the acid in distilled water.The chitosan membrane adsorbed salicylic acid by formation of hydrogen bond, hydrophobic force, and diffusion, and the slow dissociation of salicylic acid from chitosan membrane by reverse effects of adsorption.The results from this study show the validity of the real-time monitoring for the adsorption and release processes of drug molecule on carrier by dielectric analyzing.

Key words: dielectric spectroscopy, chitosan, membrane, adsorption, drug release