Abstract: Traditional Chinese medicine (TCM) has been widely used in China for thousands of years, and has received more and more recognition worldwide. Indigoplant (Folium Polygoni Tinctorii), a TCM, has been used in various diseases. In our study, we established a quality standard of Indigoplant according to the European Pharmacopoeia, and this standard has passed the early audit stages of the European Pharmacopoeia Commission. The Indigoplant samples were identified with high performance thin layer chromatography (HPTLC), qualified with RP-HPLC quantitation, and analyzed with a series of quality tests. An accurate, reliable and robust HPLC method with gradient elution for quantitation was developed and validated with a one-variable-at-a-time (OVAT) robustness approach. Several tests, including the loss on drying, total ash and ash insoluble in hydrochloric acid of Indigoplant, were performed for quality analysis. Furthermore, six batches of the Indigoplant samples were appraised with this quality standard. In conclusion, the established quality standard was more internationally normative and applicable for the quality control of Indigoplant in practical application.

Key words: Indigoplant, European Pharmacopoeia, Quality standard, HPTLC, Robustness