Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water
Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water
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DOI：
10.3390/nano9010035
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发表时间：
2019-01-01
期刊：
影响因子：
5.3
通讯作者：
Linden, Mika
中科院分区：
文献类型：
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作者：
Mutschler, Anna;Stock, Vivian;Linden, Mika
水中痕量汞的检测涉及几个复杂问题，包括复杂的多步骤分析程序，使用额外的有害试剂，增加污染的风险，以及需要昂贵的分析设备。在这里，我们提出了一种直接的无试剂方法，用于汞痕量测定，使用一种新型的薄膜采样棒，用于基于金纳米颗粒的被动采样。纳米颗粒支撑在硅片上，并进一步覆盖一层薄薄的介孔二氧化硅。介孔二氧化硅层作为保护层，防止金在暴露于水时解吸。金纳米颗粒是通过对真空蒸发制备的硅片上的均匀金层进行热处理而产生的。随后通过浸渍涂层覆盖一层介孔二氧化硅。通过以扩散控制的方式将溶解的汞离子掺入金基质中，从水样（例如河水）中提取。因此，在采样过程中积累的汞量取决于水样的汞浓度、积累时间以及基质的大小。因此，实验条件可以选择，以适应任何给定的汞浓度水平，而不损失灵敏度。用原子荧光光谱法对气相汞进行热解吸后，测定棒上收集的汞量。此外，基板可以重复使用几十次而不会损失任何性能，并且批对批的变化是最小的。因此，纳米金-介孔二氧化硅取样底物可以高度灵敏、简单、无试剂地测定水中痕量汞浓度，也适用于现场分析。通过对认证标准物质ORMS-5（一种河水）中汞浓度的测量，证明了该方法的有效性。
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.