Rapid determination of three alkaloids from Lotus Plumule in human serum using an HPLC-DAD method with a short monolithic column

An HPLC-DAD with a short monolithic column method was used for rapid, sensitive and simultaneous determination of liensinine, isoliensinine and neferine in human serum. Chromatographic separation was achieved on an RP-HPLC chromolithic column (50 mm × 4.6 mm i.d.), with a mobile phase of methanol-water-triethylamine-acetic acid (70:30:0.2:0.05), at a flow rate of 1 ml min^-1. The calibration curves of three alkaloids exhibit good linear relationship in the concentration range of 0.5-80 μg ml^-1. The limits of detection (LODs) of three alkaloids were 20, 20 and 25 ng ml ^-1, respectively, and the separation time was 4 min. A comparative study has been performed with a normal C₁₈ packed column (150 mm × 4.6 mm i.d.; 5 μm). The separation time was 16 min and the LODs of three alkaloids were 56, 56 and 65 ng ml^-1, respectively.