Extraction and preconcentration of diclofenac through adsolubilisation process using magnetic nanoparticles adsorbent prior to its spectrophotometric determination

A novel, fast and sensitive method based on cetyltrimethyl ammonium bromide-coated Fe₃O₄ nanoparticles as an efficient adsorbent was developed for solid-phase extraction of diclofenac. The unique properties of magnetic nanoparticles (MNPs) including high surface area and superparamagnetism give the method the advantages of high extraction capacity, fast separation and low consumption of the adsorbent. The main parameters affecting extraction and desorption efficiency, such as the amount of surfactant, pH of the sample solution, desorption conditions, breakthrough volume, amount of MNPs, extraction and desorption times, and ionic strength, were investigated and optimised. Under optimum conditions, the method was successfully applied to determine the analyte and good linearity in the range of 50-1400 ng mL^-1 (r² = 0.9998) was achieved with a low detection limit of 15 ng mL^-1. The relative standard deviations of 2.76 and 1.73% (for a concentration of 50 and 500 ng mL^-1, respectively) and a high enrichment factor of 98 were obtained. The method was successfully applied for the determination of diclofenac from spiked human plasma and urine samples and good recoveries in the range of 96-101% were obtained.