LC-MS/MS Determination of Methylphenidate in Human Plasma

OBJECTIVE To establish an LC-MS/MS method for determination of methylphenidate in human plasma. METHODS 1.0 mL plasma was basified with 40 μL 2 mol·L^-1 NaOH and extracted with 4 mL ether. The separation was performed on an Eclipse XDB-C₁₈ column (150 mm×4.6 mm, 5 μm). The mobile phase consisted of methanol and water for gradient elution. Methylphenidate was determined by LC-MS/MS operated in the positive ion mode. RESULTS The limit of quantitation was 0.1 ng·mL^-1, and a good linearity was obtained in the range of 1–100 ng·mL^-1(r=0.999 1). The RSD of inter-day and intra-day precision were less than 8%. Each analysis was completed within 10 min. CONCLUSION The method is accuracy, sensitive and simple, proved to be suitable for the study of therapeutic drug monitoring of methylphenidate.