Comparison of liquid chromatography with fluorescence detection to liquid chromatography-mass spectrometry for the determination of fluoxetine and norfluoxetine in human plasma

A comparison study on fluoxetine (FL) and norfluoxetine (NORFL) quantitation in human plasma was carried out between the recently developed liquid chromatographic method with fluorescence detection (LC-FLD) and an earlier established liquid chromatography-mass spectrometry (LC-MS) laboratory procedure. Comparative method evaluation was based on the analysis of plasma samples obtained from Parkinsonian patients receiving 20 mg of FL per day. The LC-FLD method involves a two-step liquid extraction procedure without any derivatization, followed by direct chromatography on a Zorbax C8 reversed-phase column. The analytical results are discussed in terms of the method validation and the corresponding experimental protocol (r >= 0.998; CV < 9%; LOQ 20 mu g/l). There was good correlation between FL, as well as NORFL, plasma levels as determined by the LC-MS and LC-FLD techniques (r = 0.9597, N = 16 and r = 0.9852, N = 14 for FL and NORFL, respectively). The results confirm that direct FL/NORFL fluorimetric determination is acceptable for routine use in pharmacokinetic and clinical studies. (c) 2005 Elsevier B.V. All rights reserved.