A nebulizer design for inductively coupled plasma spectrometry

电感耦合等离子体光谱分析(ICPOES)和电感耦合等离子体质谱(ICPMS)是无机分析化学中最重要的分析工具。在这些系统中，液体样品被雾化成小液滴并被引入等离子体。为了正确的操作，液滴的尺寸应该很小，最好小于5微米。大多数商用系统使用气动雾化器，可产生大范围的液滴尺寸分布，主要在1-100微米的范围内。因此，在雾化器下游增加了一个喷雾室，以去除大液滴。然而，这导致只有一小部分(不到5%)的雾化样品实际对测量信号有贡献。对于非常小的样品尺寸，使用微雾化器，它有非常小的小孔来产生小液滴，以供小样品吸收。然而，这些体系容易堵塞和堵塞，特别是对于高粘度溶液和含有完全溶解固体的溶液，使它们基本上不切实际。尽管大量的研究和大量的出版物致力于液体样品的引入，但这个问题仍然是限制原子光谱分析效率的因素。我们正在提出一种新的液体样品雾化方法，我们相信这将显著提高电感耦合等离子体系统的效率。提出的方法是基于使用超声波雾化器和受控气体混合系统来限制液滴的碰撞和合并。超声波雾化器可以设计成产生非常小的液滴(~5微米)。然而，在某些频率下的液滴大小也取决于液体的性质。本研究的一个目标是确定这一对广泛的实际流体性质的依赖关系，并确定在相对较高的粘度(高达100 CP)时保持较小液滴尺寸所需的超声波频率和幅度。本研究的另一个目标是开发一种混合室，以快速分散超声雾化器产生的高密度气溶胶，以防止二次碰撞和合并，这可能导致液滴尺寸增加。

Inductively coupled plasma optical emission spectroscopy (ICP-OES) and mass spectrometry (ICP-MS) can be considered as the most important tools in inorganic analytical chemistry. In these system, a liquid sample is atomized into small droplets and introduced into a plasma. For a proper operation, the droplet sizes should be small, preferably less than 5 microns. Most commercially available systems use pneumatic nebulizers, which generate a broad range of droplet size distributions, mainly in the range of 1-100 microns. Therefore, a spray chambers is added downstream of the nebulizer to remove large droplets. This, however, results that only a small fraction (less than 5%) of the nebulized sample actually contributes to the measured signal. For very small sample sizes, micro-nebulizers are used, which have very small size orifices to generate small droplets for small sample uptakes. However, these systems are prone to blockage and clogging, in particular for high viscosity solutions and solutions containing total dissolved solid, making them basically impractical. Despite a significant amount of research and the high number of publications devoted to liquid sample introduction, this problem still persists to be what limits the efficiency of atomic spectrometry.We are proposing a novel method for the nebulization of liquid samples, which we believe would significantly improve the efficiency of ICP systems. The proposed method is based on using an ultrasound nebulizer in combination with a controlled gas mixing system to limit the droplet collision and coalescence. Ultrasound nebulizers can be designed to generate very small droplets (~ 5micorns). However, the droplet sizes at certain frequencies also depends on the liquid properties. One objective of the present research is to determine this dependency for a wide range of practical fluid properties, and determine the ultrasound frequency and amplitude needed to keep the droplet sizes small for a relatively higher viscosities (up to 100 cP). Another objective of the present research is to develop a mixing chamber to rapidly disperse the high density aerosol that is generated by the ultrasound nebulizer in order to prevent secondary collision and coalescence, which may result in an increase in droplet sizes.