Chemical-based species classification of rhubarb using simultaneous determination of five bioactive substances by HPLC and LDA analysis.

INTRODUCTION

Rhubarb is a traditional Chinese medicine derived from the rhizome of three species: Rheum tanguticum, Rheum palmatum and Rheum officinale. There are several species that are often misidentified as rhubarb. Taxonomical identification of these various species can be challenging. We have developed an HPLC-based species classification to identify rhubarb.

OBJECTIVE

The objective of this study was to develop a simple HPLC method for the simultaneous determination of bioactive compounds and identification of medicinal rhubarb rhizome and non-medicinal species.

METHODOLOGY

Quantitative analysis was performed on a C₁₈-column using 0.05 M aqueous phosphoric acid and acetonitrile as the mobile phase under gradient conditions with ultraviolet detection at 280 nm. The method was validated with respect to linearity, accuracy, precision, and recovery. Statistical analysis was used to classify different groups of species.

RESULTS

All calibration curves showed good linearity (r ≥ 0.9995). The method showed good repeatability with intra- and inter-day standard deviations of less than 1.13% and 1.32%, respectively. The accuracy and recovery of all marker compounds were in the ranges of 98.0 to 102.6% and 99.21 to 102.04%, respectively. Seventeen peaks were selected, and 39 known and 57 unknown samples were classified into five species based on linear discriminant analysis with an accuracy of 100%.

CONCLUSION

A chemical-based species classification method of rhubarb using simultaneous determination of bioactive compounds by HPLC was developed with 39 known samples of five different species and successfully applied to identify 57 unknown samples collected from Korea and China.