Sustainable and reagent-free mercury trace determination in natural waters using nanogold dipsticks
Sustainable and reagent-free mercury trace determination in natural waters using nanogold dipsticks
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DOI：
10.1016/j.microc.2019.03.032
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发表时间：
2019-06
影响因子：
4.8
通讯作者：
Maria Schlathauer;Jens Friedland;M. Lindén;K. Leopold
中科院分区：
文献类型：
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作者：
Maria Schlathauer;Jens Friedland;M. Lindén;K. Leopold
测定水圈中汞的痕量是一项重要且仍然具有挑战性的分析任务。本文报道了一种新的固相萃取（SPE）方法，利用新开发的纳米金包覆试纸测定天然水中的总溶解汞（Hg）。试纸棒的直接制备包括将高尔夫膜沉积在由aptms涂层的无孔二氧化硅颗粒（ø = 300 nm）修饰的玻璃基板上。随后的退火处理在平面取样棒表面形成了一层固定的金纳米颗粒（AuNP）层，并通过电子显微镜对其进行了详细的表征。为了选择性地将汞积累到这种活性AuNP层中，试纸浸入水样中几秒钟，最高可达10 min，这取决于样品的浓度范围和所需的灵敏度。热解吸后，通过原子荧光光谱（AFS）进行定量分析。考察了固相萃取的持续时间、温度、湍流和停滞条件以及汞释放加热时间等参数，并对其进行了优化。提取时间为10 min时，检出限低至0.18 ng Hg L−1；浸渍时间仅为10 s时，检出限为10 ng L−1。重现性高，相对标准偏差≤4.9% （n = 3）。此外，单独制备的试纸的高重复性和低批次间变化证实了该方法的可行性。在真实海水（R = 105%）、河水（R = 98%）和认证标准物质ERM-CA400（海水，R = 94%）中进行了成功的回收率实验，验证了优化方法的有效性。
Determination of mercury traces in the hydrosphere is an important and still challenging analytical task. Here we report on a novel solid phase extraction (SPE) method for total dissolved mercury (Hg) determination in natural waters using newly developed nanogold-coated dipsticks. Straightforward preparation of the dipsticks comprises golf film deposition onto glass substrates modified with APTMS-coated non-porous silica particles (ø = 300 nm). Subsequent annealing process leads to an immobilized gold nanoparticle (AuNP) layer on the surface of the flat sampling sticks, which was characterized in detail by electron microscopy. For selective Hg accumulation into this active AuNP layer, the dipstick is immersed in the water sample for a few seconds up to 10 min depending on the concentration range of the sample and desired sensitivity. After thermal desorption of Hg from the sticks subsequent quantification by atomic fluorescence spectroscopy (AFS) is performed. Several parameters for SPE like duration, temperature, turbulent and stagnant conditions, as well as heating duration for Hg release were investigated and optimized. The limit of detection was found to be as low as 0.18 ng Hg L−1for 10 min extraction duration and calculated to be 10 ng L−1for a dipping time of only 10 s. High reproducibility with relative standard deviations ≤4.9% (n = 3) is given. In addition, high repeatability and low batch-to-batch variation for individually prepared dipsticks confirm feasibility of the approach. The validity of the optimized approach was confirmed by successful recovery experiments in real seawater (R = 105%), river water (R = 98%) and the certified reference material ERM-CA400 (seawater; R = 94%).