Alkaloid analysis by high-performance liquid chromatography-solid phase extraction-nuclear magnetic resonance: New strategies going beyond the standard

► HPLC-SPE-NMR study of 24 model alkaloids. ► Protocol for HPLC-SPE-NMR trapping of alkaloids on GP resin after dilution with NaOH. ► Evaluation of MM cation exchange sorbent for HPLC-SPE-NMR trapping of alkaloids. ► GP resin shows poor elution of polyaromatic alkaloids with methanol-d4.