One-step preparation of a biphasic monolithic separation media for enriching and purifying lupeol in medicine plants

Abstract

In this study, a monolith consisted of two materials with different separation modes were prepared by a one-step method at both ends of a column. Acrylic acid and 2-hydroxyethyl methacrylate (HEMA) were used as monomers for hydrophilic and hydrophobic parts, respectively. The total pore volumes and porosities of hydrophilic and hydrophobic materials were 3.1098 mL/g and 75.2535 %, 4.4380 mL/g and 72.5317 %, respectively. The prepared monolithic columns had excellent mechanical strength and good permeability, and can bear high flow rates up to 5 mL/min. The biphasic monolith functioned in two retention modes: hydrophilic interaction chromatography (HILIC) and hydrophobic interaction chromatography (HIC), and the dual-mode were realized by switching the ratio of acetonitrile in the mobile phase. The biphasic monolithic column was used as solid phase extraction (SPE) adsorbent for on-line enrichment and purification of lupeol in Chinese herbal medicines (CHM), which showed good adsorption performance and excellent reproducibility. The spiked recoveries were from 88.52 % to 93.68 % under the optimal experimental conditions; the repeatability could reach 100 times. The method showed good linearity in the range of 0.13 ∼ 2.00 × 103 μg /mL with a correlation coefficient of r = 0.9991; the limit of detection (LOD) was 0.023 μg/mL and the limit of quantification (LOQ) was 0.076 μg/mL; the intra-day and inter-day precisions were both less than 1.05 %.