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

Abstract

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 200μL of plasma mixed with 200μL of borate solution (pH 9), followed by liquid desorption of the drug with 200μL acetonitrile in a single cycle. The DPX/LC–FD method demonstrated a linear response over the dynamic range from 10 to 1000ngmL−1 for fluoxetine and from 80ngmL−1 (LOQ) to 1000ngmL−1 for norfluoxetine with r2=0.997 and 0.998, respectively. The limit of quantification (LOQ) was 10ngmL−1 for fluoxetine and 80ngmL−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.