resumo
Reliable determination of mercury (Hg) in natural waters is a major analytical challenge due to its low concentration and to the risk of Hg losses or contamination during sampling, storage and pre-treatment of samples. The present work proposes a simple, efficient, sensitive and easy-handling methodology for extraction, pre-concentration and quantification of total dissolved mercury in natural waters, using iron oxide nanoparticles (NPs) coated with silica shells functionalized with dithiocarbamate groups (Fe3O4@SiO2SiDTC). Ten mg L-1 of these NPs were sufficient to remove 83-97% of 500 to 10 ng L-1 of Hg in ultra-pure water and artificial seawater, used as model Hg solutions, within 24 h. Mercury sorbed to the NPs was then measured directly by thermal decomposition atomic absorption spectrometry with gold amalgamation. The detection limit of approximately 1.8 ng L-1 is lower than the values reported in dispersive solid phase extraction for other magnetic sorbents. As a proof-of-concept, the proposed methodology was successfully tested in real samples of fresh and saline waters and more than 91% of Hg was recovered. With this methodology the extraction and pre-concentration steps may be carried out in situ decreasing the risk of Hg losses or contamination during sampling, storage and pre-treatment of water samples. (C) 2018 Elsevier Ltd. All rights reserved.
palavras-chave
SOLID-PHASE EXTRACTION; ENVIRONMENTAL WATER; SILICA-GEL; CARBON NANOTUBES; AQUEOUS-SOLUTION; TRACE ANALYSIS; HG2+ IONS; MICRO; PRECONCENTRATION; REMOVAL
categoria
Environmental Sciences & Ecology
autores
Tavares, DS; Vale, C; Lopes, CB; Trindade, T; Pereira, E
nossos autores
Cláudia Batista Lopes
Investigador Auxiliar
Daniela Soraia dos Santos Tavares
Estudante de doutoramento
Tito Trindade
Professor Catedráticoagradecimentos
This work was supported by the National Funding for Science and Technology (FCT) through doctoral and postdoctoral grants to D.S. Tavares ISFRH/BD//103828/20141 and to C.B. Lopes [SFRH/BPD/99453/2014]; and the University of Aveiro, FCT/MEC for the financial support to CESAM, CICECO and CIIMAR [UID/AMB/50017/2013; UID/CTM/50011/2013; UID/Multi/04423/2013], through national funds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement. The work is connected objectives of the project CORAL -Sustainable ocean exploitation: tools and sensors (NORTE-01-0145-FEDER-000036).