Determination of the marker compound, chikusetsusaponin IVa in Dolichos lablab L. using HPLC–PDA and HPLC–ELSD

Abstract

Dolichos lablab L. (Leguminosae) has been used as food or health supplementary food for a long time. The aim of this study is to establish the method of quantitative analysis of chikusetsusaponin IVa for quality assessment of D. lablab using high-performance liquid chromatography (HPLC) with photodiode array (PDA) detector and evaporative light scattering detector (ELSD). Chikusetsusaponin IVa was isolated from water soluble fraction of D. lablab extract. The column for quantitative determination of chikusetsusaponin IVa was SunFire™ C18 column (4.6 × 250 mm, 5 μm) with maintained at 40 °C. Mobile phase was composed 0.1% (v/v) trifluoroacetic acid in water and acetonitrile. The drift tube temperature and nitrogen pressure in ELSD were 60 °C and 360 KPa. The injection volume and flow-rate were 10.0 μL and 1.0 mL/min. The coefficient of determination of calibration curve were 0.9997 (PDA) and 0.9995 (ELSD) and showed good linearity. The recovery of chikusetsusaponin IVa was 100.02–102.02% with relative standard deviation (RSD) value <2.00%. The RSD values of intraday and interday precisions were ≤2.79%. The content of the chikusetsusaponin IVa was detected 0.216 ± 0.004 mg/freeze-dried extract g (PDA) and 0.203 ± 0.004 mg/ freeze-dried extract g (ELSD). The established HPLC assay could be used as a basis for quality assessment of products containing D. lablab and/or D. lablab.