Abstract
Knowing that copolymers of acrylonitrile (AN) with acrylic acid (AA) can be used for the molecular imprinting, three AN: AA copolymers were synthesized by radical copolymerization in emulsion without emulsifier. The copolymer and diosgenin were dissolved in dimethylformamide (DMF) in order to obtain casting solutions with various polymer and template concentrations. The influence of the copolymer and template on the rheological behavior of the solutions was studied in order to establish the best parameters for the casting solutions preparation. The polymer solutions were transformed in membranes by phase inversion in water at room temperature (20oC). By casting the polymer solutions on a glass surface and drawing down with a scraper, a 200 mm thickness film resulted. The diosgenin was extracted from the membrane structure with ethanol, methanol or chloroform in an ultrasonic bath. The molecular imprinting was proved by HPLC on liquid (the extracting solvent after the membrane extraction) and solid phases (after dissolution of membrane parts in DMF). Comparing the sorption capacities of the imprinted materials, for two steroids (diosgenin and stigmasterol), the membrane selectivity towards the template was proved. Keywords: imprinted polymer, molecular recognition, solid phase extraction, bioactive substances,phase inversion