Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction

MARTINIS, E.M.; WUILLOUD, R.G.

SPECTROCHIMICA ACTA A: MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

ELSEVIER

Lugar: Amsterdam; Año: 2016 p. 111 - 115

0584-8539

This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by organic-coated Au nanoparticles (NPs) based on vortex-assisted liquid-liquid microextraction (VALLME) coupled with microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr)-coated Au NPs with Hg2+ after their interaction in a VALLME. Spectroscopic measurements of the TOABr-Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied. The limit of detection (LOD) was 0.8 ng mL-1 and the calibration curve was linear at concentrations near the LOD and up to at least 120 ng mL-1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL-1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity for trace Hg determination in tap and mineral water samples.