Science and Education Publishing World Journal of Analytical Chemistry 1 1 2013 08 13 Solid Phase Extraction of Silicate by Sorption on Modified Magnetite Nanoparticles and Spectrophotometric Determination 49 53 EN Mohammad Ali Karimi Department of Chemistry, Payame Noor University, Tehran, Iran Abdolhamid Hatefi-Mehrjardi Sayed Zia Mohammadi Alireza Mohadesi Javad Yarahmadi Asghar Askarpour Kabir Havva Mahmoodian Shahla Nezhad Khorasani WJAC2013141 10.12691/wjac-1-4-1 2013 06 23 2013 08 11 2013 08 13 A new adsorbent of alumina-coated magnetite nanoparticles (ACMNPs) modified with cetyltrimethyl ammonium bromide (CTAB) was prepared for the separation/preconcentration of trace silicate from water samples and then determined by spectrophotometry method. Silicate was determined based on the molybdenum blue method, which monitored at ¦Ë_max of 830 nm. MNPs and ACMNPs characterized by SEM and VSM. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation of silicate were 70 (for 350 mL of sample solution), 0.040 ¦Ìg mL^?1, 0.8-7.0 ¦Ìg mL^?1 and 2.2 % (for 5.0 ¦Ìg mL^-1, n=7), respectively. The method was applied to the separation/preconcentration and determination of silicate in tap water, river water and seawater samples with satisfactory results.