Extraction and preconcentration of methylphenidate from urine using silica-coated magnetic nanoparticles

Magnetic nanoparticles (MNPs) have various applications including gas detectors, magnetic liquids, catalysts, magnetic storage systems, photomagnetic materials, magnetic resonance imaging, drug delivery systems, microwave devices, Fe3O4 silica-coated magnetic nanoparticles to adsorb analytes from biological samples. Methylphenidate is an amphetamine-like compound with urinary excretion that is prescribed to treat depression, symptoms of narcolepsy, and some patients with refractory hyperactivity. Initially, Fe3O4 magnetic nanoparticles were synthesized and coated with silica. To evaluate these nanoparticles, techniques such as Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and X-ray diffraction (XRD) were used. The mean diameter of synthesized Fe3O4 and SiO2@Fe3O4 MNPs was about 45 nm and 72 nm, respectively. Two IR-FT absorption bands (636 and 656 cm cm^-1) have demonstrated the presence of MNPs.

By experiment on a real sample, the desorption yield was 91.5%, which indicates the effectiveness of the synthesized nanoparticles in extracting methylphenidate from the urine sample. Solvent type, extraction time, stirring speed, and ionic strength were investigated during the extraction process, and the optimal amount of each factor was determined using the Taguchi method, then the analyte extraction rate was measured under optimal conditions. The results showed that this method can successfully remove and extract methylphenidate from biological samples.