An efficient analytical method based on molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) was established for the determination of iridoid glycosides (IGs) in Di-huang pills. As the solid-phase extraction medium, superhydrophilic molecularly imprinted polymers (MIPs) with high affinity and selectivity to IGs in water media were fabricated using divinyl galactose as a single cross-linking monomer. The structure, porosity, and hydrophilicity of MIPs were characterized. The properties involving dynamic adsorption, kinetic adsorption, and selectivity were evaluated. Under optimal conditions the MISPE-HPLC-DAD based method was applied for loganin, morroniside, cornin, and sweroside determination in three kinds of Di-huang pills. The limits of detection of four IGs were 0.002-0.003 mg g-1. Furthermore, the proposed method exhibited some merits including good linearity, excellent precision, and desirable accuracy. The established MISPE-HPLC-DAD method has great potential for the selective determination of IGs in Chinese patent drugs. Graphical Abstract ᅟ.
Keywords: Di-huang pills; Iridoid glycosides; Single cross-linking monomer; Solid-phase extraction; Superhydrophilic molecularly imprinted polymers.