Fig. 3.

Identification of the arachidonic acid derivative in serum sample. (a) The XIC of 12-HETE or 11-HETE in serum sample, standard solution and standard addition serum samples; (b)The chemical structure of 12-HETE and 11-HETE; (c) The MS² spectrum of 12-HETE in serum sample and in 12-HETE standard solution; (d) The MS³ spectrum of fragment ion m/z 373.32 (391.33–373.32) in serum sample and in 12-HETE standard solution. LC separation was performed on an Acquity UPLC BEH Phenyl column (50 × 2.1 mm i. d., 1.7 μm; Waters, Milford, USA) with a flow rate of 0.4 mL/min at 40 °C. FA in water (0.1%, v/v, solvent A) and ACN/MeOH (7/3, v/v, with 0.1% FA, solvent B) were employed as mobile phases for analysis. A gradient of 0–5 min 20–30% B, 5–17 min 30–40% B, 17–19 min 40-20% B was used.