Solid Phase Extraction–Spectrophotometric Determination of Phosphate Using Modified Magnetite Nanoparticles as Extractor

In this work, a new, simple and fast method for the solid phase extraction-spectrophotometric determination of phosphate using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs) has been developed. The determination of phosphate is based on the molybdenum blue method which was monitored at λmax of 810 nm. MNPs and ACMNPs characterized by SEM, VSM, and XRD spectroscopy. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. Under the optimal experimental conditions, the preconcentration factor (PF), detection limit (DL), linear range (LR) and relative standard deviation (RSD) of phosphate were 80 (for 400 mL of sample solution), 0.038 µg mL−1, 0.8-10.0 µg mL−1 and 2.5 % (for 5.0 µg mL-1, n=7), respectively. The proposed method was successfully applied to the separation/preconcentration and determination of phosphate in different water samples and suitable recoveries were obtained.