A Practical Cryogen-Free CO2 Purification and Freezing Technique for Stable Isotope Analysis
A Practical Cryogen-Free CO2 Purification and Freezing Technique for Stable Isotope Analysis
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DOI：
10.1021/acs.analchem.7b00544
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发表时间：
2017-04-18
影响因子：
7.4
通讯作者：
Matsuda, Shinichi
中科院分区：
文献类型：
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作者：
Sakai, Saburo;Matsuda, Shinichi
自20世纪初开始通过质谱法进行同位素分析以来，用于轻元素同位素测量的样气已通过使用冷冻剂和真空线系统进行纯化。然而，这种常规的净化技术只能达到取决于冷冻剂的某些温度，并且只能在有连续的冷冻剂供应时才能维持。在这里，我们展示了一个实用的冷冻剂免费CO2纯化技术，使用电操作的制冷机稳定同位素分析。这种方法基于便携式自由活塞斯特林冷却技术，并在室温至-196摄氏度（液氮温度）的范围内将温度控制在0.1摄氏度的精度。最低温度可以在短短10分钟内达到。我们成功地净化了碳酸盐和磷酸反应产生的CO2气体，并发现其升华点为-155.6摄氏度，在0.1托的真空线。这意味着CO2捕集所需的温度远高于液氮温度。我们的便携式冷却系统能够免除稳定同位素分析中使用冷冻剂的不便。它还提供了一种新的冷却方法，适用于许多使用气体测量的领域。
Since isotopic analysis by mass spectrometry began in the early 1900s, sample gas for light-element isotopic measurements has been purified by the use of cryogens and vacuum-line systems. However, this conventional,purification technique can achieve only certain temperatures that depend on the cryogens and can be sustained only as long as there is a continuous cryogen supply. Here, we demonstrate a practical cryogen-free CO2 purification technique using an electrical operated cryocooler for stable isotope analysis. This approach is based on portable free-piston Stirling cooling technology and controls the temperature to an accuracy of 0.1 degrees C in a range from room temperature to -196 degrees C (liquid-nitrogen temperature). The lowest temperature can be achieved in as little as 10 min. We successfully purified CO2 gas generated by carbonates and phosphoric acid reaction and found its sublimation point to be -155.6 degrees C at 0.1 Torr in the vacuum line. This means that the temperature required for CO2 trapping is much higher than the liquid-nitrogen temperature. Our portable cooling system offers the ability to be free from the inconvenience of cryogen use for stable isotope analysis. It also offers a new cooling method applicable to a number of fields that use gas Measurements.