Abstract
Rhubarb (Rhei rhizoma), a commonly used Chinese herb, contains anthraquinones, anthrones, galloylglucoses, stilbenes, and flavan‐3‐ols compounds, etc. as major constituents. Using 19 of these compounds as markers, an HPLC‐UV‐MS method was developed to estimate the quality of rhubarb samples within a period of 70 min. Extracts were analyzed with a Cosmosil 5C~18~‐MS column and eluted with a gradient comprising an aqueous solution of acetic acid and methanol at a flow rate of 0.9 mL/min. Peaks were detected by absorbance measurements at 254 nm (6 and 8–19) and 280 nm (1–5 and 7), and the peaks of the marker substances were identified from their UV spectra and MS fragmentation patterns. The proposed method yielded a peak–area ratio RSD value with an intraday SD falling within 0.71–1.78% and an interday SD within 0.78–1.98% at a detection limit of 0.2–3.2 μg/mL. The ESI negative ion mode was used to collect data (molecular weight, CID fragments from MS and MS/MS spectra) for 19 compounds from four types of structure categories: anthraquinones, dianthrone glycosides, stilbenes, and galloylglucosides. The information gathered can be used to identify the structures of various peaks appearing in the LC chromatograms of rhubarb samples.