Selective liquid chromatographic method for determination of fluoxetine in plasma.

A selective and sensitive liquid chromatographic method was developed for the determination of fluoxetine (FLU) in plasma. FLU was isolated from plasma by liquid‐liquid extraction. The chromatographic separation was performed on an analytical 250 〈 3.9 mm id Novapak C18 column (4 μm particle size) with an isocratic mobile phase consisting of phosphate buffer‐acetonitrile‐methanol ‐triethylamine (58 + 30 + 10 + 2, v/v) adjusted to pH 7. Using UV detection at 226 nm, the detection limit for FLU in plasma was 3 ng/mL. No interferences were found with tricyclic antidepressant drugs, which allows this method to be used in clinical studies. The calibration curve was linear over the concentration range of 10‐200 ng/mL. The average recovery was about 80% for plasma. The inter- and intraday assay coefficients of variation were <8%.