The development of a new disposable pipette extraction phase based on polyaniline composites for the determination of levels of antidepressants in plasma samples.

In the present work, a new stationary phase for disposable pipette extraction (DPX) based on composites of polyaniline and a styrene-divinylbenzene (SD) copolymer was applied to the analysis of fluoxetine and norfluoxetine in plasma samples using liquid chromatography and fluorescence detector (LC-FD). The DPX variables, such as number of draw/eject cycles, sample pH, type and volume of the desorption solvent, were optimized to established the sorption equilibrium and shorten the analysis time. Among the DPX evaluated variables, the higher extraction efficiency were obtained with 200 µL of plasma mixed with 200 µL of borate solution (pH 9), followed by liquid desorption of the drug with 200 µL acetonitrile in a single cycle. The DPX/LC-FD method demonstrated a linear response over the dynamic range from 10 to 1000 ng mL(-1) for fluoxetine and from 80 ng mL(-1) (LOQ) to 1000 ng mL(-1) for norfluoxetine with r(2)=0.997 and 0.998, respectively. The limit of quantification (LOQ) was 10 ng mL(-1) for fluoxetine and 80 ng mL(-1) for norfluoxetine. Based on the analytical validation results, the proposed method can be a useful tool for determining the fluoxetine and norfluoxetine levels in plasma samples from patients receiving therapeutic dosages.