Insitu ultrasound-assisted synthesis of Fe3O4 nanoparticles with simultaneous ion co-precipitation for multielemental analysis of natural waters by total reflection X-ray fluorescence spectrometryElectronic supplementary information (ESI) available. See DOI: 10.1039/c3ja50067e

• Main Authors: Romero, Vanesa, Costas-Mora, Isabel, Lavilla, Isela, Bendicho, Carlos
• Format: Article
• Language: English
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/c3ja50067e

In this work, in situ ultrasound-assisted magnetite synthesis with simultaneous ion co-precipitation (UAMS-SIC) was applied to magnetic solid-phase extraction (MSPE) of Cu, Zn, Ge, As, Se, Re, Au, Hg, Tl, Bi and Pb. The magnetic solid phase (MSP) enriched with metal ions was directly analyzed by total reflection X-ray fluorescence (TXRF). Magnetite nanoparticles (Fe 3 O 4 NPs) were synthesized by sonochemical treatment of a solution containing Fe( ii ) and Fe( iii ) in the presence of target analytes so that these are trapped by occlusion or surface adsorption during the formation of Fe 3 O 4 NPs. In situ synthesized Fe 3 O 4 NPs were easily separated from the aqueous matrix by applying an external magnetic field, and hence, no filtration or centrifugation steps were necessary. A 10 L aliquot of MSP was deposited onto a sample quartz glass siliconized carrier and analyzed by TXRF, thus avoiding the elution step. The effect of the Fe( ii ):Fe( iii ) molar ratio, total mass of Fe in the MSP, ultrasound amplitude, time and interfering ions on the extraction efficiency of the metal ions was investigated. Detection limits ranged from 0.3 to 26 g L 1 depending on the metal ion. Enrichment factors (EFs) in the range 8180 were achieved. A recovery study carried out on spiked samples showed recoveries in the range 89109% with relative standard deviations below 10% ( N = 5). An effective, fast and sensitive procedure that can be used for field analysis is accomplished. A comprehensive characterization of in situ synthesized Fe 3 O 4 NPs was carried out by atomic force microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Finally, a co-precipitation mechanism for trace metal ions with this novel synthesis of nanosized magnetite is approached using the BerthelotNernst and the DoernerHoskins laws. In situ ultrasound-assisted synthesis of Fe 3 O 4 nanoparticles with simultaneous ion co-precipitation prior total reflection X-ray fluorescence multielemental analysis is performed.