Solid-phase extraction of β-sitosterol from Oldenlandia diffusa using molecular imprinting polymer

The β-sitosterol imprinted polymer was prepared for selective extraction and analysis of β-sitosterol from Oldenlandia diffusa (O. diffusa) followed by HPLC with UV detection. The imprinted polymers show high affinity and selectivity to β-sitosterol. Using this molecularly imprinted polymer (MIP) cartridge as solid-phase extraction (SPE) material, the interferences could be quickly washed out and β-sitosterol was selectively retained and enriched. HPLC analysis method was used to evaluate the characteristics of this MIP material. At the condition of mobile phase composed of MeOH/H₂O/H₃PO₄ (99/1/0.1, V/V/V, pH=6.0) and the flow rate of 1.0 mL·min^-1, a good linear relationship was demonstrated when the concentrations of β-sitosterol were in the range of 0.50-100.0 μg·mL^-1. The recoveries ranged from 75.3% to 86.5% and the inter-day and intra-day relative standard deviations were less than 5%. This developed HPLC method was proved to be acceptable for extraction of β-sitosterol from O. diffusa.