Quantification of gingerols and shogaols by UHPLC–MS/MS analysis

A previously validated analytical method (UHPLC–MS/MS) was used for the determination of gingerols and shogaols [17]. The quantification of gingerols and shogaols was performed with a UHPLC (Nexera ×2 system consisting of LC-30AD, SIL-30AC, STO-20AC, Shimadzu, Tokyo, Japan) coupled to a triple quadrupole mass spectrometer (TQ8040, Shimadzu). The analytical conditions including the column, mobile phase, quantitative and qualitative MRM transitions were adopted from the previous report [17]. Briefly, the column used was a short core shell column (Kinetex, 2.1 mm × 50 mm, 2.6 μm particle, Phenomenex, Torrance, CA, USA). The mobile phase system was composed of 0.05 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). The mobile phase gradient program was as following: gradient program of 0–0.01 min, 60% B; 0.01–0.90 min, 60–90% B; 0.90–2.00 min, 90% B; 2.00–2.10 min, 90–60% B; 2.10–2.50 min, 60% B. The flow rate of mobile phase was 1.0 mL min⁻¹. The injection volume was 1 μL and the column temperature was maintained at 40 °C. The quantitation of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol was conducted with the external calibration curves of their authentic compounds, respectively. The contents of 8-shogaol and 10-shogaol, which were not commercially available, were calculated with calibration curves of 6-shogaol. The quantity of gingerols and shogaols in ginger was expressed mg/kg ginger on the base of dry weight.