Gold-Coated Silica as a Preconcentration Phase for the Determination of Total Dissolved Mercury in Natural Waters Using Atomic Fluorescence Spectrometry

Abstract

A novel solid-phase preconcentration method is reported, using in-house gold-coated silica adsorbent packed in a microcolumn, for the determination of dissolved mercury in natural waters by atomic fluorescence spectrometry (AFS). The adsorbent was prepared by chemical reduction of a Au(III) solution with hydroxylamine in the presence of suspended silica particles. The resulting Au nanoparticles on the silica surface were highly efficient for adsorbing different mercury species from acidified waters without additional reagents. The acidified aqueous samples were passed over the microcolumn, either incorporated in a fully automated flow injection (FI) system directly coupled to the AFS or as part of a portable FI system for in situ preconcentration. After rinsing and drying of the column, Hg 0 was released by heating and directed to the AFS cell for quantification. The method offers significant advantages because no reagents are needed for species conversion, preconcentration, sample storage, or desorption and therefore the risk of contamination is minimized and blank values are lowered. This results in a low detection limit of 180 pg L -1 using a sample volume of only 7 mL and good reproducibility, with relative standard deviations <3.2% (n ) 10, [Hg] ) 5 ng L -1 ). Recoveries were all >90% in spiked river waters (spiked [Hg] ) 0, 1, 5, 10 ng L -1 ), and the experimental value for the certified reference material ORMS-4 (elevated mercury in river water) was 22.3 ( 2.6 ng Hg L -1 which was in good agreement with the certified value of 22.0 ( 1.6 ng Hg L -1 (recovery ) 101%). The method was successfully applied to seven different natural waters and wastewaters ([Hg] 0.5-4.6 ng L -1 ) from south west England.

Interações Mercúrio-Selênio: Uma Abordagem Integrada De Avaliação De Exposição Ao Mercúrio Em Populações Ribeirinhas No Município De Porto Velho, Rondônia

“…Figura 1 -Ciclo biogeoquímico do mercúrio (Leopold et al, 2009 Figura 2 -Bioacumulação e biomagnificação do metilmercúrio ao longo da cadeia trófica (Leopold et al, 2009 …”

Ultra-trace determination of mercury in river waters after online UV digestion of humic matter

“…S1 in the Electronic supplementary material (ESM). Preparation of the nano-gold adsorption material and set-up of the collector have been described in detail by the authors elsewhere [20].…”

“…Quantification of mercury traces after preconcentration of dissolved mercury species onto nano-gold collectors had been successfully validated by measurement of two certified reference materials, namely a river water (ORMS-4) [20] and a coastal seawater (BCR 579) [17] obtaining quantitative mercury recoveries. However, application of these reference materials for validation of the proposed online UV digestion method is not useful, because DOC contents of at least 2.5 mg L −1 are required in order to make the pretreatment necessary in the first place.…”

“…The concentration ranges for DOC in natural waters, defined as organic carbon passing a filter of 0.45 μm [19], are lower than 0.5 mg L −1 for seawaters, 1 to 10 mg L −1 for river waters, and 10 to 50 mg L −1 for moorland waters. Hence, seawaters as well as most river waters typically can be analyzed without any pretreatment by application of nano-gold collectors for preconcentration [20]. For humic-rich waters, in contrast, a pretreatment step such as ultraviolet (UV) irradiation is required prior to preconcentration.…”

Ultrasensitive determination of mercury in human saliva by atomic fluorescence spectrometry based on solidified floating organic drop microextraction

“…The detection limits (DL) of these mentioned analytical instruments are very sensitive and can meet the requirements for detection of mercury in a wide range of concentrations. However, a preconcentration step of mercury has to be used before detection when its level is very low [10,[15][16][17][18][19][20][21]. So, it is significant and necessary to develop new methods for the enrichment of mercury in some special samples before analysis [22][23][24][25].…”