Development of an analytical method for yam saponins using HPLC with pulsed amperometric detection at different column temperatures

Yam saponins (dioscin, gracillin, protodioscin, and protogracillin) were analyzed with three different C18 columns at incremental column temperatures from 15 to 45°C to investigate the effect of temperature on the retention and resolution of yam saponins. At low temperature, yam saponins showed decreased retention times and improved resolutions in the C18 columns. In the Kinetex C18 column at 15°C, the four saponins achieved baseline separation (Rs > 1.5) within 30 min. Pulsed amperometric detection was used to identify saponins with high sensitivity. The limits of detection and quantification of saponins were 0.11–0.31 and 0.33–0.95 ng, respectively. The correlation coefficients ranged 0.9986–1.0000. Intra‐ and inter‐day precisions were