Solvent extraction-spectrophotometric determination of trace amounts of fluoxetine in pharmaceutical formulations

A simple, reproducible, and sensitive extraction-spectrophotometric method for the determination of fluoxetine (FL) in pharmaceutical formulations is reported. The FLH+ cation, which is formed in an acidic solution, can form an ion-pair with Orange II, (OR II), an anionic dye. The FLH+-OR II− ion pair was quantitatively extracted into dichloromethane solvent and its absorption was measured at 482 nm. The calibration graph is linear over the FL concentration range of 0.2–9.0 μg/mL and the regression coefficient is 0.9995. The relative standard deviation (RSD) of ten replicate determinations of 5.0 and 1.4 μg/mL of FL are 0.022 and 0.038, respectively, and the limit of detection (LOD) of the method is 0.17 μg/mL. The method was successfully applied to the determination of an FL amount in pharmaceutical formulations (10.0-and 20.0-mg capsules).