Selectivity of molecularly imprinted solid phase extraction for sterol compounds

MIPs (molecularly imprinted polymers) for 17β-estradiol were prepared using 2-(trifluoromethyl) acrylic acid (TFMAA) as functional monomer and trimethylolpropane trimethacrylate (TRIM) as cross-linker by precipitation polymerisation. Data from HPLC system were calculated, and separation properties of several MIPs were reported. MISPEs (molecularly imprinted solid phase extractions) were performed with MIPs as sorbent, and absorption properties of the MISPEs prepared by UV irradiation initiating polymerisation at a ratio of 1/4 (17β-estradiol/TFMAA) for 17α-estradiol, 17β-estradiol, 4-androstene-3, 17-dione and progesterone investigated by detecting filtrates at each stage of sampling, washing and elution. Elution trials proved that addition acid or alkali reagents might affect retention of the MISPE and CSPE (control/no molecularly imprinted solid phase extraction) for 17β-estradiol. A competition test implicates that the MISPE has the strongest specific retention and enrichment for progesterone. In the actual experiment for 17β-estradiol with extracting solution of milk powder as samples, the MISPE showed better selectivity and enrichment property than C18 and CSPE, and the recovery on the MISPE was up to 85.5%.