Determination of dl-tetrahydropalmatine in Corydalis yanhusuo by l-tetrahydropalmatine imprinted monolithic column coupling with reversed-phase high performance liquid chromatography

A method for direct determination of dl-tetrahydropalmatine (dl-THP) in Corydalis yanhusuo, a traditional Chinese herb, by l-THP imprinted monolithic precolumn on-line/off-line coupling with reversed-phase high performance liquid chromatography (RP-HPLC) was developed. The l-THP imprinted monolithic column has been prepared by in situ polymerization using methacrylic acid (MAA) and ethylene dimethacrylate (EDMA) as functional monomer and cross-linker, respectively. With the optimization of chromatographic conditions, such as mobile phase composition, flow rate, column temperature and sample loading, for the separation of enantiomer, dl-THP was base-line separated on the MIP. The imprinted monolithic column was used as a precolumn for fractionation of the C. yanhusuo extract. Both the non-retained and retained fractions were separated by RP-HPLC. Meanwhile, the d-THP and l-THP can be detected in the non-retained and retained fractions, respectively. Additionally, direct determination of l-THP using molecularly imprinted monolith on-line coupling with a reversed-phase column was acquired.