Mercury (Hg) is an admittedly toxic element. From an analytical viewpoint, Hg volatility makes preparation of samples containing Hg as well as Hg detection therein a challenging task. The quality of the results is mainly associated with sample pretreatment. Moreover, there are difficulties inherent to thermal stabilization in the graphite furnace during atomic absorption. Here, Hg was determined in different samples (clay soil, sewage sludge, and light sandy soil) by high-resolution continuum source graphite furnace atomic absorption spectroscopy (HR CS GFAAS). Three different sample preparation methods were investigated: slurry, microwave acid digestion with HF and HNO₃ (which resulted in total sample decomposition), and acid leaching with aqua regia. Different chemical modifiers (palladium nanoparticles (PdNPs), Pd(II) solution, gold nanoparticles (AuNPs), and Au(III) solution) were tested, and their efficiencies were compared. Both the slurry method and acid leaching with aqua regia prevented Hg loss and yielded satisfactory results as compared to the certified, indicative or spiked concentrations of all the samples (confidence level 95%), using AuNPs as a chemical modifier. The Au–Hg amalgam resulting from a Hg(II) reduction in the AuNP surface leads to diffusion and alloying. Hg determination in the sewage sludge sample agreed with the certified value for all studied modifiers, when the sample is prepared by aqua regia leaching and slurry. Pd(II) solution and PdNPs also provided good results, but under specific conditions. Pd(II) binds to the analyte, thereby avoiding Hg loss during the pyrolysis step. As for AuNPs, they are an effective modifier because they enhance the interaction between the clusters formed after pyrolysis and prevent Hg loss, confirming the potential for application of these modifiers.

中文翻译：

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HR CS GFAAS测定土壤和污泥样品中的汞：样品制备程序和化学改性剂的比较†

汞是公认的有毒元素。从分析的角度来看，汞的挥发性使得含汞样品的制备以及其中的汞检测成为一项艰巨的任务。结果的质量主要与样品预处理有关。此外，在原子吸收过程中石墨炉中的热稳定所固有的困难。在此，通过高分辨率连续谱源石墨炉原子吸收光谱法（HR CS GFAAS）测定了不同样品（粘土，污水污泥和轻质沙质土壤）中的Hg。研究了三种不同的样品制备方法：浆液，HF和HNO _3的微波酸消解（导致样品总分解）以及王水的酸浸。测试了不同的化学改性剂（钯纳米粒子（PdNPs），Pd（II）溶液，金纳米粒子（AuNPs）和Au（III）溶液），并比较了它们的效率。与使用AuNPs作为化学改性剂的所有样品的认证浓度，指示浓度或加标浓度（可信度95％）相比，浆液法和王水酸浸均可以防止汞损失，并产生令人满意的结果。由于AuNP表面的Hg（II）还原而产生的Au-Hg汞齐导致扩散和合金化。当通过王水浸出和淤浆制备样品时，污水污泥样品中的汞测定与所有研究的改性剂的标准值一致。钯（II）溶液和PdNPs也提供了良好的结果，但是在特定条件下。Pd（II）与分析物结合，从而避免了热解步骤中的汞损失。至于AuNPs，它们是有效的改性剂，因为它们增强了热解后形成的簇之间的相互作用并防止了Hg的损失，从而证实了使用这些改性剂的潜力。