*2.3. Sample Preparation Step*

Honey (1.0 g) was mixed with 5 mL of water and vortexed for 2 min. Alkaloid was isolated using PRS cation exchange cartridges preconditioned with 5 mL of methanol and 5 mL of Milli-Q water. The mixed sample was passed through the PRS cartridges at a flow rate of less than 5 mL/min. Then, the PRS cartridges were rinsed with 10 mL of Milli-Q water and all effluent was discarded. The retained alkaloid was eluted with 8 mL of 5% ammoniated methanol. The eluate was evaporated to 0.5 mL using a gentle steam of nitrogen. Then, the sample was transferred quantitatively with methanol into a 1 mL volumetric flask, obtaining a final extract in 100% methanol. One milliliter of the extract was filtered through a 0.22-μm microbore cellulose membrane for 2D-LC analysis.
