Simultaneous determination of cis- and trans-palmitoleic acid in rat serum by UPLC–MS/MS

Palmitoleic acid, a monounsaturated fatty acid which could affect glucose and lipid metabolism and reduce insulin resistance has two isomers, i.e. cis -palmitoleic acid ( c POA) and trans -palmitoleic acid ( t POA). However, the pharmacokinetic, metabolic transformation and structure–activity relationship of the two isomers have not been reported. A precise and accurate ultra performance liquid chromatography–tandem mass spectroscopy (UPLC–MS/MS) method was developed to determine c POA and t POA simultaneously. Both the c POA and t POA were administered i.g. (intragastric gavage) to rats at 75 mg/kg. Serum samples were collected and analyzed for the two isomers by UPLC–MS/MS on a reverse-phase BDS C18 column equilibrated and eluted with water (A) and acetonitrile (B) at a flow rate of 0.3 mL/min. The calibration curves for c POA and t POA were linear over the range 0.1–12 μg/mL. Analytes were monitored by selected-reaction monitoring in negative electrospray ionization mode. The Tmax of c POA was 0.94 ± 0.44 h and the Cmax 8.17 ± 1.97 μg/L, and the Tmax and Cmax of t POA were 1.50 ± 0.98 h and 14.77 ± 11.91 μg/L, respectively. AUC 0–24 h of c POA and t POA were 59.45 ± 29.83 and 113.88 ± 72.25 mg/L·h. The method was applied in pharmacokinetic study of c POA and t POA in rat serum successfully. Besides, the concentrations of c POA and t POA in rat serums were observed fluctuating with a consistent trend, which may be due to reciprocal bio-convert in the body.