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Open AccessArticle

Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water

1
Department of Inorganic Chemistry II, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
2
Department of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
3
Department of Physics, Chemistry, and Biology, Linköping University, 58183 Linköping, Sweden
*
Authors to whom correspondence should be addressed.
Equal contribution.
Nanomaterials 2019, 9(1), 35; https://doi.org/10.3390/nano9010035
Received: 26 November 2018 / Revised: 14 December 2018 / Accepted: 20 December 2018 / Published: 28 December 2018
(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)
Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water. View Full-Text
Keywords: gold nanoparticles; mesoporous silica films; mercury trace analysis gold nanoparticles; mesoporous silica films; mercury trace analysis
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MDPI and ACS Style

Mutschler, A.; Stock, V.; Ebert, L.; Björk, E.M.; Leopold, K.; Lindén, M. Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water. Nanomaterials 2019, 9, 35.

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