Simultaneous separation and determination of four phenylethanoid glycosides in rat plasma sample after oral administration of Cistanche salsa extract by microemulsion liquid chromatography

A simple, rapid and specific method was developed to separate as well as to determine the four phenylethanoid glycosides (PhGs) (echinacoside, tubuloside B, acteoside and isoacteoside) in rat plasma after oral administration of Cistanche salsa extract by reversed phase high performance liquid chromatography using a microemulsion as the mobile phase. The separations were performed on a Zorbax Extend-C18 column at 25 °C. Photodiode-array detector was conducted at 322 nm and with a flow rate of 0.8 mL min−1. The optimized microemulsion mobile phase consisted of 0.3% triethylamine in 20 mM phosphoric acid at pH 6.0, 0.8% (v/v) ethyl acetate as oil phase, 1.5% (v/v) Genapol X-080 as surfactant, 2.5% (v/v) n-propanol as co-surfactant. Under the optimal conditions, the calibration curve for four PhGs was linear in the range of 10-1000 ng mL−1 with the correlation coefficients greater than 0.9994. The intra-day and inter-day precision (RSD) were below 8.64% and the limits of detection (LOD) for the four PhGs were 0.4-1.3 ng mL−1 (S/N = 3). The microemulsion liquid chromatography (MELC) method was successfully applied to separate and determine the four PhGs in rat plasma after oral administration of C. salsa extract.