LC-ESI-MS determination of oxiracetam in human plasma

Objective:To develop a LC-ESI-MS method for determination of oxiracetam in human plasma.Methods:After addition of piracetam as internal standard,protein precipitation by methanol was used as sample preparation.Chromatographic separation was achieved on a Zorbax SB-C18(2.1 mm×100 mm,3.5 μm)column with(5:95,v/v) methanol-water containing 0.1% formic acid as mobile phase.Electrospray ionization(ESI) source was applied and operated in positive ion mode and selected ion monitoring(SIM) mode was used to quantify oxiracetam using target fragment ions m/z 158.5 for oxiracetam and m/z 142.5 for the IS.Results:Calibration plots were linear over the range of 0.1~8 μg/ml for oxiracetam in plasma.Lower limit of quantitation(LLOQ) for oxiracetam was 0.1 μg/ml.Mean recovery of oxiracetam from plasma was 91.5%~96.4%.RSD of intra-day and inter-day precision was less than 9%,respectively.Conclusion:This method is simple,sensitive and fast enough to be used in pharmacokinetic research for determination of oxiracetam in plasma.