【作者】 锁然；

【导师】 孙汉文；

【作者基本信息】 河北大学 ， 分析化学， 2004， 博士

【摘要】 由于氢化物发生法（化学蒸气发生法）采用化学反应实现待测组分与大量基体相分离，一方面消除了可能的光谱干扰，另一方面由于待测物以气体方式引入，使其进样效率及原子化效率大幅度提高，显著提高了分析的灵敏度，是解决复杂基体样品分析和元素形态分析中检测问题的有效进样方式，并为价态分析、形态分析及分离富集等工作开辟了一个新领域。近年来，氢化物发生法的元素应用范围成为该领域一个重要的研究方向。目前，元素范围已经扩展至周期表d区的过渡金属和贵金属元素，但是这些元素的蒸气发生效率还很低，且反应机理和产物属性还不清楚。过渡金属和贵金属元素能否和怎样与硼氢化钾（钠）进行反应形成某种挥发性物种这一问题，无论是在对这些元素分析方法的建立（对于特殊基体样品），还是在这些元素对其它元素氢化物发生的干扰研究方面均有着十分重要的意义。针对这些问题，首次详细、合理地提出了与四氢硼化钾（钠）反应的氢化物生成反应机理，认为金属元素的挥发性氢化物是BH₄^-中的负氢“转移”至金属原子M的产物，而不是通过与“新生态氢”反应形成的，负氢的转移可能是通过金属离子与BH₄^-形成的过渡中间配合物分解完成的。以提出的氢化物发生反应机理为基础，以锌、镉、铜和镍为例，研究了提高过渡金属和贵金属元素氢化物产率的措施。实验结果发现，合适的络合剂、过渡金属离子以及表面活性剂的存在，可以显著提高锌、镉、铜和镍的蒸气发生效率。关于这些试剂的增效机理，从氢化物发生反应历程（机理）的角度给予了合理的解释。并以断续流动氢化物发生原子荧光法研究了Zn、Cd、Cu和Ni挥发性物种的性质。实验结果表明，Cd的挥发性物种是不稳定的氢化物分子CdH₂，而Zn、Cu和Ni在它们的蒸气中分别以稳定氢化物分子的“气溶胶”形式存在。 在周期表d区元素的氢化物发生反应应用研究中，将镉和镍的氢化物发生气相富集技术与石墨炉原子光谱法结合，分别建立了测定超痕量镉的氢化物发生石墨炉原位富集法以及测定痕量镍的氢化物发生吸收液富集石墨炉原子吸收光谱法和石墨炉原位富集法，并成功应用于生态环境样品的分析。在镍氢化物的吸收液富集法中，采用了分析方法中常用的稀硝酸溶液:在石墨炉原位富集分析法中，分别采用持久性的铱、把/铱涂层，使石墨炉对锅和镍的富集效率显著提高，简化了分析操作，提高了分析灵敏度，实现了对痕量、超痕量镍和锅的简便、高灵敏度的分析检测。更多还原

【Abstract】 The technique of hydride generation (chemical vapor generation) can separate the analyte from the matrix of samples by chemistry reaction, which will avoid the possible spectrum interference, and significantly improve the sensitivity of analytical procedure due to the efficiency improvement of sampling and atomization by gaseous sample introduction. It is an effective method of sample introduction to solve problems in the analysis of samples with complex matrix and speciation, which opened a new field for the work of valence state analysis, speciation analysis and enrichment. In recent years, expanding the scope of vapor (hydride) forming elements became an important research aspect in this field. Up to now, the scope has been expanded to the transition and noble elements. However, the vapor generation efficiency of the transition and noble elements are very low, and the reaction mechanism and the nature of the volatile production remain unknown. To know whether or not and how the transition and noble elements produce some volatile species by reacting with tetrahydroborate is meaningful for both the analysis method establishment of those elements (for the samples with special matrix) and the research of interference from those elements with the hydride generation of other elements. A reasonable mechanism of hydride generation via reaction with tetrahydroborate was proposed for the first time in detail, of which the volatile hydrides of metal elements were produced by the transfer of negative hydrogen from BH4- to the metal atom, rather than by the reaction of metal atom with the nascent hydrogeon. Thetransfer of negative hydrogen was accomplished by the decomposition of a transient intermediate produced by the reaction of metal ion with BH4-. Taking Zn, Cd, Cu and Ni for example, the approaches to improve the hydride generation efficiency of transition and noble metals were studied on the basis of the hydride generation mechanism proposed. As a result, the hydride generation efficiency of Zn, Cd, Cu and Ni were significantly improved by some complexes, transition metal ions and surfactants. The enhancing mechanism of these reagents was reasonably explained in view of the reaction mechanism of hydride generation. The nature of volatiles of Zn, Cd, Cu and Ni were investigated by the intermittent flow hydride generation atomic fluorescence spectrometry. It was found that the volatile species of Cd was unstable hydride CdH2 while the volatile species of Zn, Cu and Ni were stable hydride molecules presented as aerosol form in the vapor.In the application studies of hydride generation of d zone elements in periodic table, the gaseous phase enrichment techniques in hydride generation of cadmium and nickel were coupled with graphite furnace atomic absorption spectrometry. The detection method of ultra trace cadmium using hydride generation graphite furnace atomic absorption spectrometry after in situ trapping on a coated graphite tube with permanent modifier Ir was developed. The detection methods of trace nickel using hydride generation graphite furnace atomic absorption spectrometry after in situ trapping on a coated graphite tube with permanent modifier Pd/lr and trapping in 0.5 mol L-1 HNO3 solution were respectively established. The methods proposed were sensitive and simple, and successfully applied to the analysis of ultra trace cadmium and trace nickel in environmental samples更多还原