Analysis of Ginsenosides in Sheng-Mai-Yin Decoction by High Performance Liquid Chromatography-Diode Array Detection-Electrospray Ionization Mass Spectrometry

A method of high performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD/ESI-MS) in a negative ion mode was developed for the analysis of ginsenosides in Sheng-Mai-Yin decoction (Panax gingeng C. A. Mey, Ophiopogon japonicus (Thunb.) Ker-Gawl, Shisandra chinensis (Turcz.) Baill.). The analyses were preformed on a reversed-phase C18 column (4.6 mm i.d. × 150 mm, 5 μm) using a binary eluent (10 mmol/L ammonium acetate (A)-acetonitrile (B), 1 mL/min) under gradient conditions (60%A–40%A at 0–30 min, 40%A–30%A at 30–40 min). Seventeen ginsenosides (20 (R)-Rh1, Rh2, Rg3, Rg2; 20 (S)-Rh1, Rh2, Rg3, Rg2; Rf, Rg6, Rg5, F4, Rk1, Rk3, Rh4; 20 (S)-, and 20 (R)-protopanax-atriol) were well separated and detected at 203 nm using a DAD detector. The effluent from the DAD detector was introduced into the electrospray ionization source in a postcolumn splitting flow at a rate of 0.3 mL/min. In the mass spectrum, two major ions, [M-H]− and [M+AcO]−, were observed for ginsenoside standards (20 (R)-Rh1, Rg3, Rh2; 20 (S)-Rh1, Rg3, Rh2; 20 (S)-, and 20 (R)-protopanaxatriol) and for ginsenosides in Sheng-Mai-Yin decoction. Certain other ions [M-Glc-H]−, [M-2Glc-H]−, [M-Rha-H]−, and [M-Rha-Glc-H]− were also found in the mass spectrum of ginsenosides of Sheng-Mai-Yin decoction. During the preparatory process of decoction, ginsenosides transformed into constituents of moderate and low polarity by hydrolysis, isomerization, and dehydration at the site of C-20, and hydrolysis reaction also occurred at the site of C-3 or C-6. The above-mentioned study presents a quick and accurate assay method that can be used for the qualitative analysis of ginsenosides in Sheng-Mai-Yin decoction and for the quality control of Sheng-Mai-Yin preparations.