Determination of Gallic Acid in Rat Plasma by LC-MS-MS

Liquid chromatography-electrospray ionization tandem mass spectrometry has been used for rapid, selective, and sensitive quantitative analysis of gallic acid in rat plasma. Sample pretreatment involved a one-step extraction using ethyl acetate with protocatechic acid as internal standard. Separation was on a C(18) column using an isocratic mobile phase, consisting of methanol-0.1% aqueous formic acid (40:60, v/v) at 0.2 mL min(-1). The stability of gallic acid was evaluated in acidified and non-acidified plasma. The method was validated then successfully applied to a pharmacokinetic study in rats after oral administration of rhubarb extract.