Determination of alkaloids in Corydalis yanhusuo using hollow-fibre liquid phase microextraction and high performance liquid chromatography

Hollow fibre based liquid phase microextraction (HF-LPME) with high performance liquid chromatography (HPLC) was developed for the determination of alkaloids in Corydalis yanhusuo. Three alkaloids (protopine, tetrahydropalmatine, tetrahydroberberine) were extracted from a 10 mL alkaline sample (donor phase) to an organic phase impregnated in the pores of the hollow fibre, and then, they were extracted to an acidic solution (acceptor phase) in the lumen of the fibre. The extract was determined directly by HPLC. Parameters affecting the HF-LPME include the organic solvent, pH of the donor and the acceptor phase, the extraction time and the stirring speed were investigated systematically. To minimize the error of the injection, palmatine was added as an internal standard (I.S.). Under optimal conditions, calibration curves were obtained in the range of 0.1–1.0 mg L⁻¹ with a reasonable linearity (r ² > 0.993) and the limits of detection (LODs) ranged between 10.0 × 10⁻³ mg L⁻¹ and 13.7 × 10⁻³ mg L⁻¹. Additionally, enrichment factors with 100 to 184-fold were obtained. The method was then applied to the crude extract of Corydalis yanhusuo successfully.