Separation/preconcentration and speciation of very low amounts of selenium using modi ed  agnetite nanoparticles before electrothermal atomic absorption spectrometric determination in water


1 Department of Chemistry, Payame Noor University, Tehran, P.O. Box 19395-4697, Iran.

2 Department of Chemistry & Nanoscience, and Nanotechnology Research Laboratory (NNRL), Payame Noor University, Sirjan, P.O. Box 78185-347, Iran


A new, simple, fast and reliable procedure for the speciation of selenium(IV) and selenium(VI) using Solid-Phase Extraction (SPE) with ammonium pyrrolidine dithiocarbamate/ sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (APDC/SDS-ACMNPs), followed by electrothermal atomic absorption measurement, is proposed. The method is based on the adsorption of Se(IV) on modi ed ACMNPs. Total selenium concentration in di erent samples was determined as Se(IV), after reduction of Se(IV) to Se(VI), by heating the samples in a microwave oven with 4.0 mol L1 HCl. Se(VI) concentration was calculated as the di erence between the total selenium content and Se(IV) content. The e ect of parameters such as pH, amount of adsorbent, contact time, sample volume, eluent type, and HCl and APDC/SDS concentration ratios as modi ers, on the quantitative recovery of Se(IV), was investigated. Under optimal experimental conditions, the preconcentration factor, detection limit, linear range and Relative Standard Deviation (RSD) of Se(IV) were 125 (for 250 mL of sample solution), 0.05 ng mL1, 0.1- 8.0 ng mL1 and 4.1% (for 5.0 ng mL1; n = 7), respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of APDC/SDS-ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of selenium in di erent water samples and suitable recoveries were obtained.