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

电感耦合等离子体质谱法（ICP- ms）和ICP原子发射光谱法（ICP- aes）采用氩ICP作为电离源或激发源，已广泛应用于痕量元素分析。遗憾的是，由于氩等离子体的电离能力不够高，很难激发出高电离势的元素。为了克服这个问题，人们期望开发其他强大的等离子体源，例如氦ICP。本课题组研制了一种用于质谱和AES的新型直注多气ICP源。在常压下，除了Ar外，He、O_2、N_2、CO_2、N_2O、空气及其混合等离子体也能稳定生成。火炬由同轴三石英玻璃管组成，管内有冷却气体、等离子体气体和载气流动。为了在等离子体产生区域产生足够的涡旋流，即使使用氦气，火炬具有较小的气体入口和短至…氦气的运动粘度是其他气体的9倍左右，因此氦气的涡旋流很容易转变为层流。认为冷却气体可能混入等离子体中，导致原子发射光谱（AES）本底发射增大，原子发射光谱（ms）本底离子发射增大。本文研究了冷却气体种类和流量对Ar和He ICP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，还可以减少进入等离子体的大气混合物。此外，水溶液也可以像DIN（直喷式雾化器）或DIHEN（直喷式高效雾化器）一样，使用传统的雾化器直接导入等离子体。新的火炬有一个支持气体流动周围的雾化溶液，以减少扩散到等离子体的溶液。因此，注入溶液的扩散角有效减小。提高了样品的发射强度，扩大了直接注入等离子体稳定产生的实验条件。研究了新型直接注入多离子ICP源的光谱特性。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