The concentrations of aconitum alkaloids were determined by utilizing a Waters Xevo TQD-Acquity UPLC H-Class Bio system equipped with an ESI source (Thermo Finnigan, San Jose, CA, USA). The chromatographic analysis was performed on an Acquity UPLC BEH C18 column (1.7 μm, 2.1 × 50 mm2) at room temperature. The mobile phase was water containing 0.05% formic acid (phase A) and 100% acetonitrile (phase B) with a gradient elution program at a flow rate of 0.3 mL min−1, 0–1 min, 15% phase B; 1–2.5 min, 30% phase B; 2.5–4 min, 45% B; 4–4.1 min, 90% phase B; 4.1–6 min, 15% phase B. The injection volume was 10 μL and the auto-sampler temperature was maintained at 15 °C.
The mass scan mode was the positive MRM mode. For instance, the precursor ion and product ion were m/z 646 → 586 for aconitine and m/z 330 → 181 for sinomenine as internal standard, respectively. The collision energy for aconitine and internal standard were 34 eV and 30 eV, respectively. The MS/MS conditions were optimized as follows: spray voltage, 3.5 kV; ion source temperature, 150 °C; sheath gas pressure, 50 L h−1; auxiliary gas flow, 50 L min−1; capillary temperature, 400 °C.
The mass scan mode was the positive MRM mode. For instance, the precursor ion and product ion were m/z 646 → 586 for aconitine and m/z 330 → 181 for sinomenine as internal standard, respectively. The collision energy for aconitine and internal standard were 34 eV and 30 eV, respectively. The MS/MS conditions were optimized as follows: spray voltage, 3.5 kV; ion source temperature, 150 °C; sheath gas pressure, 50 L h−1; auxiliary gas flow, 50 L min−1; capillary temperature, 400 °C.