Modified iron oxide nanoparticles as solid phase extractor for spectrophotometric determination and separation of cationic surfactants

Complete text of publication follows. A novel, simple method based on magnetically assisted chemical separation (MACS) has been developed to the separation and preconcentration of cationic surfactants i.e. dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC). Cationic surfactants were substituted quantitatively from aqueous solution onto magnetic nano-adsorbent with cationic dye methylene blue (MB+) immobilized on sodium dodecyl sulfate (SDS)-coated Fe3O4 nanoparticles (MB-S-IONPs). Spectrophotometric determination method used for the determination of cationic surfactants is based on the competition between the MB+ and cationic surfactant (CS+) for association complex formation with SDS. The MB+ in the ion associate complex can be quantitatively substituted by CS+ leading to an increase in the absorbance measured at 662 nm. Optimum experimental conditions for separation, preconcentration and determination of cationic surfactants have been reported. Method was validated using a set of different samples containing cationic surfactants. The advantages of this method include consumption of organic solvents almost eliminated and applications on unclear (containing suspended particles) samples without any preliminary filtration step. This method combines simplicity and selectivity of solvent extraction with easy separation of magnetic nanoparticles from solution with magnet. The proposed method is more simple and cheaper than old other methods, furthermore, in this method, we don't need to use complex pretreatment or toxic organic solvents. In other words, it belongs to green chemistry. This research was supported by the Department of Chemistry and Nanoscience and Nanotechnology Research Laboratory (NNRL) of Payame Noor University of Sirjan.