Ods 2 hypersil c 18 column

An Agilent 1260 infinity HPLC system was used (Agilent, Agilent Technologies. Inc., USA). An ODS-2 Hypersil C-18 column (250 mm × 4.6 mm id, 5 μm; Thermo Scientific, Thermo Fisher Scientific Inc., USA) was used at a column temperature of 35 °C. The mobile phase was acetonitrile (A) and water (B). The elution system was performed using a stepwise gradient elution of 0–14 min, 95–87% B; 14–15 min, 87–85% B; 15–16 min, 85–95% B; 16–21 min, 95–95% B. The flow rate was set at 0.9 mL/min. The effluent was monitored at 278 nm. The standard solution of DAG was determined. It showed a good linearity over a range of 0.4–16 μg for DAG. The regression equation for DAG was Y = 420.882012X + 122.39368, (R² = 0.9995, n = 6), where Y is the peak area and X is the mass.

Phytochemical analysis of QEP was performed using an Agilent 1260 Infinity LC HPLC system (Agilent, United States) and separated on an ODS-2 Hypersil C-18 column (250 mm × 4.6 mm id, 5 μm; Thermo Scientific, Thermo Fisher Scientific Inc., United States) at 30°C. The catalysts used were 0.1% formic acid aqueous solution (A) and acetonitrile (B). The gradient elution program was as follows: 0–8 min, 5%–5% B; 8–10 min, 5%–8% B; 10–25 min, 8%–8% B; 25–30 min, 8%–20% B; 30–40 min, 20%–30% B; 40–60 min, 30%–70% B; and 60–80 min, 70%–70% B. The flow rate was 1.0 ml/min, and the absorption wavelength was below 246 nm.

The HPLC system consisted of a SSI PC2000 chromatograph (SSI, Scientific Systems, Inc., USA) and a 2000ES evaporative light scattering detector (ELSD) (Alltech, Alltech Associates Inc., USA). An ODS-2 Hypersil C-18 column (250 mm × 4.6 mm id, 5 μm; Thermo Scientific, Thermo Fisher Scientific Inc., USA) was operated at 35°C. Solvents that constituted the mobile phase were acetonitrile (A) and 0.2% formic acid aqueous solution (B). The separation was performed using a stepwise gradient elution of 0–14 min, 95–87% B; 14–25 min, 87–87% B; and 25–45 min, 87–81% B; then keeping 95% B to balance for 10 min. The flow rate was 0.9 mL/min. ELSD was used as the detection method with nebulizing gas flow rate of 2.5 L/min and drift tube temperature of 105°C. The impactor position of ELSD was set off. The stock standard solution of liriodendrin was prepared and diluted six concentrations of 37–370 μg/mL. It showed a good linearity over range of 0.74–7.4 μg for liriodendrin. The regression equation for liriodendrin was Y = 1.63681X + 5.40736 (R² = 0.9992, n = 6), where Y is the logarithm peak area and X is the logarithm mass of liriodendrin.