背景:电感耦合等离子体质谱法(ICP-MS)是用于测定钨的最强大的仪器技术之一,其检出限低,线性范围宽,虽然它仍然具有挑战性,因为分析性能可能会受到复杂的样品基质的影响。化学蒸气发生(CVG)具有替代常规溶液雾化以引入样品以减少基体效应的潜力。然而,钨的CVG效率低。显然,钨的CVG的绿色和均匀增强是理想的,其机理值得深入研究。
结果:研究了两种用于钨的CVG的绿色和均匀增强系统,包括光化学蒸气发生(PVG)和氢化物发生(HG)与敏化剂,Fe3+和DDTC,分别。在最优条件下,PVG的检出限(LOD)为0.02μgL-1,HG的检出限为0.003μgL-1,分别。对于PVG,Fe3+/Fe2+循环,自由基物种,气态产品,详细研究了W在PVG过程中的化学形态演变。照片-芬顿效应,生成还原性自由基·CO2-,发现气态产物Fe(CO)5和PVG过程中W5/W6的混合价对于增强至关重要。至于HG,W(VI)和DDTC之间的络合可能有助于提高HG效率。
结论:这项工作不仅深入扩展了CVG的元素范围,而且还通过实验研究了增强机制,这可能会对CVG过程有深入的了解,并预示着将来为更多元素的CVG筛选绿色和有效的均质敏化剂的新指南。
BACKGROUND: Inductively coupled plasma-mass spectrometry (ICP-MS) is one of the most powerful instrumental techniques for the determination of tungsten for its low detection limit and wide linear range, while it remains challenging since the analytical performance can be affected by complicated sample matrix. Chemical vapor generation (CVG) harbors the potential to be an alternative to conventional solution nebulization for sample introduction to reduce matrix effect. However, the CVG of tungsten was low in efficiency. It is clear that green and homogeneous enhancement for CVG of tungsten is desired and the mechanism is worth in-depth investigation.
RESULTS: Two green and homogeneous enhancement systems for CVG of tungsten were studied, including photochemical vapor generation (PVG) and hydride generation (HG) with sensitizers, Fe3+ and DDTC, respectively. Under optimal conditions, the limits of detection (LODs) were 0.02 μg L-1 for the PVG and 0.003 μg L-1 for the HG, respectively. For PVG, the Fe3+/Fe2+ cycling, free radical species, gaseous product, and the chemical speciation evolution of W in the PVG process were studied in detail. Photo-Fenton effect, generated reductive radical ·CO2-, gaseous product Fe(CO)5, and the mixed valence of W5+/W6+ in the PVG process were found to be crucial for the enhancement. As for HG, the complexation between W(VI) and DDTC might be conducive to the enhanced HG efficiency.
CONCLUSIONS: This work not only in-depth expands the element scope of CVG, but also investigates the enhancement mechanisms experimentally, which might render a deep insight into the CVG processes and foreshadow new guidelines for screening green and efficient homogeneous sensitizers for CVGs of more elements in the future.