Development of an On-line Low Gas Pressure Cell for Laser Ablation-ICP-Mass Spectrometry
Development of an On-line Low Gas Pressure Cell for Laser Ablation-ICP-Mass Spectrometry
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DOI：
10.2116/analsci.23.1195
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发表时间：
2007-10
影响因子：
1.6
通讯作者：
T. Hirata
中科院分区：
文献类型：
--
作者：
T. Hirata
研制了一种用于激光烧蚀-电感耦合等离子体质谱（LA-ICPMS）元素分析的在线低气压池装置。样品池中的环境气体通过恒流隔膜泵抽真空，通过改变He进气流量来控制样品池的压力。当环境气压低于50 kPa时，烧蚀坑周围的样品再沉积程度降低。产生的样品气溶胶从隔膜泵的出口抽出，并直接引入ICP离子源。He气体的流速不仅控制样品池中的气体压力，而且控制样品颗粒从池到ICP的传输效率，并且必须优化气体流速以使分析物的信号强度最大化。调整He载气和Ar补充气体的流速，以使分析物的信号强度最大化，对于NIST SRM 610玻璃材料中的^238 U，He和Ar的气体流速分别为0.4 L/min和1.2 L/min时，信号强度可以达到最大。在池中得到的气体压力为30-35 kPa。使用低气压池设备，在信号强度的稳定性和由此产生的同位素比测量的精度进行了评价。激光烧蚀金属样品获得^63 Cu的信号强度分布（NIST SRM 976）证明，不再发现瞬态信号中的典型尖峰，这可能成为分析误差的一个很大来源。（n = 10，2SD），这是在大气压力下通过激光烧蚀获得的水平（6-10%）的一半。新开发的低压池设备提供了更容易的操作条件优化，以及更小程度的样品再沉积和更好的信号强度稳定性，即使是金属样品。
An on-line low gas pressure cell device has been developed for elemental analysis using laser ablation-ICP-mass spectrometry (LA-ICPMS). Ambient gas in the sample cell was evacuated by a constant-flow diaphragm pump, and the pressure of the sample cell was controlled by changing the flow rate of He-inlet gas. The degree of sample re-deposition around the ablation pit could be reduced when the pressure of the ambient gas was lower than 50 kPa. Produced sample aerosol was drawn and taken from the outlet of the diaphragm pump, and directly introduced into the ICP ion source. The flow rate of He gas controls not only the gas pressure in the sample cell, but also the transport efficiency of the sample particles from the cell to the ICP, and the gas flow rate must be optimized to maximize the signal intensity of the analytes. The flow rates of the He carrier and Ar makeup gas were tuned to maximize the signal intensity of the analytes, and in the case of ^238U from the NIST SRM610 glass material, the signal intensity could be maximized with gas flow rates of 0.4 L/min for He and 1.2 L/min for Ar. The resulting gas pressure in the cell was 30–35 kPa. Using the low gas pressure cell device, the stability in the signal intensities and the resulting precision in isotopic ratio measurements were evaluated. The signal intensity profile of ^63Cu obtained by laser ablation from a metallic sample (NIST SRM976) demonstrated that typical spikes in the transient signal, which can become a large source of analytical error, were no longer found. The resulting precision in the ^65Cu/^63Cu ratio measurements was 2–3% ( n = 10, 2SD), which was half of the level obtained by laser ablation under atmospheric pressure (6–10%). The newly developed low-pressure cell device provides easier optimization of the operational conditions, together with smaller degrees of sample re-deposition and better stability in the signal intensity, even from a metallic sample.