Quantitative Analysis of Five Kudinosides in the Large‐leaved Kudingcha and Related Species from the Genus Ilex by UPLC–ELSD

INTRODUCTION: The large‐leaved Kudingcha from the genus Ilex, which is used as a traditional Chinese tea, contains several characteristic triterpenoid saponins that can be subjected to quality control evaluation. OBJECTIVE: To develop and validate a rapid method incorporating reverse‐phase ultra‐performance liquid chromatography coupled with evaporative light scattering detection (UPLC–ELSD) for the simultaneous determination of the five triterpenoid saponins kudinoside L (1), kudinoside C (2), kudinoside A (3), kudinoside F (4) and kudinoside D (5) in several species of the large‐leaved Kudingcha from the genus Ilex and ‘Yerba Mate’ (Ilex paraguariensis). METHODOLOGY: The five compounds were separated using a water–acetonitrile mobile phase with a Waters Acquity BEH C18‐column (100 × 2.1 mm, 1.7 µm). RESULTS: Separation took 13 min with detection and quantification limits ranging from 12.5 to 29.8 ng and 41.3 to 98.2 ng, respectively. The method was validated according to the regulatory guidelines with respect to precision, stability, repeatability and recovery. The triterpenoid saponins showed a good regression relationship (r2 > 0.999) within the test ranges, and the recovery of the method was in the 95–105% range. CONCLUSION: The present method can be used successfully for the quality control of the large‐leaved Kudingcha. The different Ilex species showed differences in distribution of the five triterpenoids. Ilex kudingcha, which makes up the major species of the large‐leaved Kudingcha, contains the maximum amount of triterpenoid saponins.