Preparation of barium sulfate-coated magnetite particles for the extraction of trimethoprim from environmental water samples based on mixed hemimicelles solid-phase extraction

In this study, barium sulfate-coated magnetite particles (Fe3O4/BaSO4) for mixed hemimicelles solid-phase extraction, have been successfully synthesized by a chemical coprecipitation method. Fe3O4/BaSO4 modified by sodium dodecyl sulfate (SDS) was applied for the extraction of trimethoprim from environmental water samples. Compared with other substrates, such as alumina, silica and titanium dioxide, Fe3O4/BaSO4 particles have better stability and resistance to acidity and alkalinity. A comprehensive study on the adsorption conditions, such as the amount of SDS, pH value, standing time, desorption solvent and the maximum extraction sample volume was presented. Good recovery (72.3–85.0%) and high concentration factor (800) were achieved using only 0.1 g of Fe3O4/BaSO4 and 20 mg of SDS. The detection and quantification limits of the proposed method were 0.05 and 0.16 μg L−1, respectively. It shows great analytical potential in the preconcentration of organic compounds from large volume water samples.