Ginsenoside rb1

Ginseng under forest samples were provided by Changchun University of Traditional Chinese Medicine. Panax quinquefolius samples from different origins (Quebec, Canada and Jilin, China) were purchased from pharmacies.
Three ginsenoside standards samples, namely, ginsenoside Rb1, ginsenoside Re, and ginsenoside Ro, were provided by Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China, HPLC purity > 98%). Deionized water (18.2 MΩ/cm) was prepared using a Milli-Q Water Purification System (Billerica, MA, USA). HPLC-grade methanol was purchased from ROE Scientific Inc. (Newark, DE, USA). AR grade NH₄Cl and NH₄Ac were purchased from Xilong Chemical Co., Ltd. (Xilong, Guangxi, China). HPLC grade C₂H₅OH, HCOOH, and CH₃CN were purchased from Anpel Laboratory Technologies (Shanghai) Inc. (Shanghai, China).
Ginsenoside standard samples were dissolved in methanol to obtain standard stock solvents of all three target analytes at a final concentration of 100 μg/mL. The solvents were stored at 4 °C prior to the iEESI-MS analysis.

Dry root samples of 0.3 g were extracted in 100% methanol and sonicated for 30 min. The solution volume was fixed to 25 mL. Saponin contents were determined as described by Pharmacopoeia of People’s Republic of China (2020) . Saponin contents were measured using a high-performance liquid chromatograph (Agilent 1260; Agilent Technologies, Santa Clara, CA, USA). Notoginsenoside R₁, ginsenoside Rd, ginsenoside Rg₁, ginsenoside Re, and ginsenoside Rb₁ standards ( > 98% purity) were purchased from Yuanye Bio-technology (Shanghai, China). Kit column (250 mm × 4.6 mm, 5 μm) was used for the determination, and the mobile phase was acetonitrile (ACN)-water. Chromatographic conditions: elution with 0–5 min, 17–20% ACN; 5–20 min, 20% ACN; 20–45 min, 20–42% ACN; 45–50 min, 42–100% ACN; set with flow rate, injection volume, monitoring wavelength and column temperature of 1.0 mL·min⁻¹, 10 µL, 203 nm and room temperature, respectively. Total saponins are the sum of Rg₁, Rb₁, Re, Rd and R₁. The HPLC chromatograms of P. notoginseng root grown in different N environments are shown in Fig. S3.

Authentic standards of ginsenoside Rg₁, ginsenoside Re, ginsenoside Rf, ginsenoside Rb₁, ginsenoside Rc, ginsenoside Rg₂, ginsenoside Rh₁, ginsenoside Ro, ginsenoside Rb₂ and ginsenoside Rd, schisandrol A, schisandrol B were all purchased from Shanghai yuanye Bio-Technology Co., Ltd. (Shanghai, China). d-Fructose was purchased from National Institutes for Food and Drug Control (Beijing, China). The purity of each chemical was equal to or greater than 97%. They were stored at 4 °C before use. P. ginseng, S. chinensis, and O. japonicus extract intermediates and SMI samples were from SZYY Group Pharmaceutical Limited (Nanjing, China).
All solvents, including methanol and acetonitrile with a purity of 98% were of chromatographic grade purchased from Fisher (Hampton, NH, USA), all other reagents and chemicals were of analytical grade.