Removal, preconcentration and spectrophotometric determination of picric acid in water samples using modified magnetic iron oxide nanoparticles as an efficient adsorbent

A simple, fast and sensitive spectrophotometric method is developed for removal, preconcentration and determination of trace amounts of picric acid in water samples. Magnetic iron oxide nanoparticles (MIONPs) were synthesized and characterized by transmission electron microscopy (TEM). The magnetic nanoparticles were coated with cetyltrimethylammonium bromide (CTAB) and were applied for fast separation, preconcentration and spectrophotometric determination of picrate anion (the ion of picric acid) in an aqueous solution. The separation, preconcentration procedure is fast and will be completed in 2 min. Methanol is used for desorption of adsorbed picrate anion. The effects of important parameters such as pH of aqueous medium, CTAB dosage, adsorbent amount, temperature, electrolyte concentration, desorbing solvent and interfering ions on the adsorption of picrate anion were investigated. The method showed good linearity for the determination of picric acid in the concentration range of 0.02–1.00 μg mL− 1 with a regression coefficient of 0.999. The limit of detection (LOD) is obtained to be 0.007 μg mL− 1. The relative standard deviation (RSD) for 0.03 μg mL− 1 and 0.8 μg mL− 1 of picric acid were 3.98% and 1.97% respectively. Picric acid was separated, preconcentrated and determined successfully in spiked samples of Karoon River water.