Analytical Methodology for Sensitive Detection of the Antidepressant Drug Duloxetine in Urine Samples Using...

Antidepressant drugs are widely used and effective in treating mood disorders. Monitoring low concentrations of these drugs in biological samples such as solid tissues and biofluids with high sensitivity is challenging for conventional analysis methods. The present study aims to determine duloxetine molecules at trace levels in urine samples by using a simple sample preparation method and a high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) system. This study presents the development of a novel separation and preconcentration method for the trace-level determination of duloxetine using HPLC-DAD following magnetic solid-phase extraction (MSPE). For this purpose, tetraethyl orthosilicate (TEOS)-coated magnetic nanoparticles functionalized with riboflavin (Fe₃O₄@TEOS-riboflavin) were synthesized and thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. Following MSPE, duloxetine exhibited a linear response over the range of 10.00-800.00 ng·mL^-1 (R²: 0.9942). The limits of detection (LOD) and quantification (LOQ) were determined to be 3.28 and 9.60 ng·mL^-1, respectively. Relative standard deviations (RSDs) were below 5.1% for triplicate analyses of model solutions containing 100 ng·mL^-1 of duloxetine. Moreover, the developed method was successfully applied to both synthetic and healthy human urine samples, providing quantitative results in recovery studies. The recovery values for synthetic and human urine samples ranged from 98.1 to 102.2%, indicating that the combination of MSPE with HPLC-DAD provides a reliable approach for the accurate determination of duloxetine concentrations in urine.