Determination of 46 Ginsenosides in Different Processed Ginseng Products by Dispersive Solid Phase Extraction Combined with Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry

A method was developed for the simultaneous detection of 46 ginsenosides in different processed ginseng products by dispersive solid phase extraction combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were ultrasonically extracted with 80% methanol aqueous solution, and the extract was purified by dispersive solid phase extraction (DSPE) using primary secondary amine (PSA) as a sorbent, separated on a KINETEX XB-C18 column (2.1 mm × 100 mm, 2.6 µm) by gradient elution using a mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution, detected in the negative ion mode with multiple reaction monitoring (MRM), and quantified by an external standard method. The 46 ginsenosides were detected within 35 minutes. Under the optimized conditions, the calibration curves showed good linearities for 46 compounds at concentrations ranging from 0.02 to 50 µg/mL with correlation coefficients (R2) over 0.99. The limits of detection (LODs) and the limits of quantitation (LOQs) were in the range of 0.4–3.2 mg/kg and 1.4–10.5 mg/kg, respectively. The average recoveries at three spiked levels were in the range of 80.5%–111.6% with relative standard deviations (RSDs) of 1.3%–6.8%.  In addition, the RSDs for intra- and inter-day precision were 0.5%–4.5% and 1.1%–6.6% (n = 6), respectively. The RSDs for repeatability ranged between 1.5% and 7.3% (n = 6), and the RSDs for sample stability within 24 hours between 0.9% and 5.8% (n = 6) within 24 h. In this method, the type and dosage of DSPE sorbent were optimized, and the influence of DSPE purification on the matrix effect was investigated. The results showed the matrix interference was effectively reduced by DSPE with PSA, and the sample pretreatment was easy to operate, efficient and cost-saving. This method was successfully applied to the analysis of 46 ginsenosides in sun-dried ginseng, red ginseng and black ginseng. The results revealed that ginsenosides were transformed into rare ginsenosides in red ginseng and black ginseng due to steaming, and the contents of rare ginsenosides in black ginseng were much higher than those in red ginseng. The proposed method was accurate and reliable, fast, easy to operate, immune to impurity interference, and suitable for the simultaneous quantitative analysis of 46 ginsenosides in processed ginseng products.