Abstract

A new high-performance liquid chromatography (HPLC) coupled with evaporative light scattering detection (ELSD) method was developed, and the quantity of four major saponins, three alkaloids and three fatty acids were determined simultaneously in Solanum nigrum Linn, a commonly used traditional Chinese medicine (TCM) herb. The simultaneous separation of four saponins, three alkaloids and three fatty acids was achieved on a C₁₈analytical column. The mobile phase consisted of 0.3‰ triethylamine in acetonitrile and 0.3‰ triethylamine water-methanol (80: 20, v/v) performed on a gradient program in 80 min. The flow rate was 1.0 ml min^-1 and the column temperature was maintained at 30°C. During ELSD, the drift tube temperature was 40°C and the nebulizer nitrogen gas flow-rate was controlled at 3.5 bars. All calibration curves showed good linear regression (r² > 0.9981) within test ranges. This method showed good reproducibility for the quantification of four saponins, three alkaloids and three fatty acids in S. nigrum with intra- and inter-day variations of less than 5.0%. The validated method was successful in quantifying the four saponins, three alkaloids and three fatty acids in ten sources of S. nigrum, and provided a new basis for the overall assessment of S. nigrum quality.

Key words: HPLC-ELSD, Solanum nigrum Linn., saponin, alkaloid, fatty acid