Magnetite nanoparticles coated with covalently immobilized ionic liquids as a sorbent for extraction of non-steroidal anti-inflammatory drugs from biological fluids

Magnetic core-shell nanoparticles (mag-NPs) of type SiO2@Fe3O4 were covalently modified with the ionic liquid dimethyl octadecyl[3-(trimethoxysilyl propyl)]ammonium chloride. The NPs were characterized via FTIR and scanning electron microscopy and evaluated with respect to the extraction of the nonsteroidal anti-inflammatory drugs (NSAIDs) tolmetin, indometacin and naproxen from blood samples. Supercritical fluid extraction was used to eliminate matrix effects before extraction with the mag-NPs. The effects of pH value of sample solution, amount of adsorbent, times of adsorption and desorption, salt effect, type and volume of suitable solvent for desorption were optimized. Under optimum conditions, magnetic solid phase extraction (MSPE) resulted in limits of detection that range between 0.1 and 0.3 mu g L-1. In case of supercritical fluid extraction along with magnetic solid phase extraction (SFE-MSPE), the LODs ranged from 0.2 to 0.3 mg kg(-1). The analytical ranges for all of the NSAIDs varied within 0.2-15 mg kg(-1) and 0.1-250 mu g L-1 in the SFE-MSPE and MSPE methods, respectively. The relative standard deviations for the extraction of the NSAIDs from blood samples via SFE-MSPE are < 10.2%.