Development of Direct Injection Multi-gas ICP and Its Application of Elemental Analysis

以氩等离子体为电离或激发源的电感耦合等离子体质谱(ICPMS)和电感耦合等离子体原子发射光谱分析(ICPAES)已被广泛应用于痕量元素分析。遗憾的是，由于Ar等离子体的电离能力不够高，很难激发高电离势元素。为了解决这一问题，我们期待着开发其他强大的等离子体源，如氦等离子体源。在我们的研究小组中，已经开发了一种新的直接注入多气体电感耦合等离子体源，用于MS和AES。利用这种新的等离子体源，不仅可以在大气压下稳定地产生Ar，而且可以稳定地产生He、O_2、N_2、CO_2、N_2O、空气及其混合等离子体。火炬由三根同轴的石英玻璃管结构和管间的冷却气体、等离子体气体和载气组成。为了在等离子体产生区产生足够的涡流，即使在使用氦气的情况下，焊炬的气体入口也较小，并缩短为…更多RCH配置。氦的运动粘度比其他气体高约九倍，因此氦的涡流很容易转变为层流。本文研究了冷却气体种类和流量对Ar和He等离子体发射特性的影响。测量了N_2、Ar和He的径向发射强度。结果发现，当选择合适的气体和流量时，不仅可以减少冷却气体和空气进入等离子体的混合物，而且可以使用传统的雾化器将水溶液直接引入到等离子体中，如DIN(直接注射雾化)或DIHEN(直接注射高效雾化器)。新的焊枪在雾化溶液周围有一个支持气体流动，以减少溶液扩散到等离子体中。从而有效地减小了注入溶液的扩散角。从而提高了样品的发射强度，扩大了直接注入稳定产生等离子体的实验条件。研究了新型直接注入多砷电感耦合等离子体源的光谱特性。较少

Inductively coupled plasma mass spectrometry(ICP-MS) and ICP atomic emission spectrometry (ICP-AES) using argon ICP as an ionization or an excitation source have been widely utilized for trace elemental analysis. Unfortunately, it was difficult to excite high ionization potential elements because the ionization ability of argon plasma is not enough high. To overcome this problem, development of other powerful plasma sources, for example helium ICP, are expected.In our research group, a new direct injection multi-gas ICP source for MS and AES has been developed. With the new ICP source, not only Ar but He, O_2, N_2, CO_2, N_2O, air and their mixture plasmas can be stably generated in atmospheric pressure. The torch consists of coaxial three quartz glass tube structure and the cooling gas, the plasma gas and the carrier gas flow between the tubes. To generate an adequate vortex flow at the plasma generating region even when helium gas is used, the torch has smaller gas inlet and short to … More rch configuration. Helium has about nine times higher kinematic viscosity than other gases so the vortex flow of helium easily turn into the laminar flow. It is apprehended that the cooling gas may immix into the plasma and it cause increasing of background emission for AES and background ion for MS. In this study, effect of the cooling gas kind and the flow rate on the emission properties in Ar and He ICP are investigated. The radial emission intensities of N_2, Ar and He are measured. As a result, it was found that when appropriate gas and flow rate are chosen, mixture of not only cooling gas but atmosphere into the plasma are reduced.Furthermore, aqueous solutions can be directly introduced into the plasma like DIN (direct injection nebulize) or DIHEN (direct injection high-efficiency nebulizer) using conventional nebulizers. The new torch has a support gas flow around the nebulized solutions to reduce diffusion of the solutions into the plasma. As a result, the diffusion angle of the injected solutions effectively reduced. Then the emission intensities from the sample are increased and the experimental conditions for stable generation of plasmas with direct injection are expanded. The spectroscopic characteristics of the new direct injection multi-as ICP source are investigated. Less