Sensitive Detection of Sibutramine and Fluoxetine Adulteration in Herbal Slimming Products by Means of Using Magnetic Solid Phase Extraction Combined with HPLC–DAD

A new pre-treatment and determination methodology has been developed including magnetic solid phase extraction (MSPE) combined with high-performance liquid chromatography with diode array detector (HPLC–DAD) for the determination of trace sibutramine and fluoxetine molecules in herbal slimming products. In the proposed method, fluoxetine and sibutramine molecules were extracted with the help of newly synthesized magnetic-Fe₃O₄-based nanoparticles in the presence of a pH 10.0 medium. The analytical performance criteria of the developed method such as linear range, enrichment factor, and detection limit were studied and calculated according to official guidelines after optimization of the experimental variables of MSPE such as pH, adsorption, and desorption conditions. Fluoxetine and sibutramine molecules were determined by a HPLC–DAD system at 225 and 265 nm for fluoxetine and sibutramine using a mobile phase composed of pH 5.0 acetate buffer and methanol (30:70). The obtained detection limits from experimental results were calculated as 3.41 ng mL⁻¹ and 3.83 ng mL⁻¹ for fluoxetine and sibutramine, respectively. The accuracy of the method was evaluated by means of recovery tests in model solutions and real samples for two concentration levels. As a result of recovery experiments, the values were found in the range of 94.8–104.5% while relative standard deviation (RSD %) values were below 6.0%.