Qualitative and Quantitative Analysis of Linoleic Acid in Polygonati Rhizoma

Objective: To explore the major compound in Polygonati Rhizoma (Huang Jing, 黄精) for quality control. Methods: The major compound was isolated and analyzed by liquid chromatography-mass spectrometry (LC-MS), and subsequently further identified by nuclear magnetic resonance (NMR). Thin layer chromatography (TLC) was optimized based on the previous methods reported in the Chinese Pharmacopeia (2015 edition). Results: The major compound was isolated from the natural material and identified as linoleic acid. A high performance liquid chromatography (HPLC) method with robust linearity (R2 = 0.999 7), specificity, precision, stability, repeatability and recovery was developed for linoleic acid determination. TLC chromatogram was improved significantly after optimization for qualitative analysis. Conclusions: The optimized TLC method is practical and can be adopted for quality control of Polygonati Rhizoma (Huang Jing, 黄 精 ). The levels of linoleic acid vary between species of Polygonati Rhizoma (Huang Jing, 黄 精 ), with Polygonatum cyrtonema Hua (Jiang Xing Huang Jing, 姜型黄精) showing the highest contents. This study provides valuable information for quality control of Polygonati Rhizoma (Huang Jing, 黄精).