"A practical cryogen-free CO2 purlification technique for stable isotopes" has been published in ACS Analytical Chemistry.
Since isotope analysis started in the early 1900s, the sample gas for light-element isotopic measurements has been purified using “cryogens” in a vacuum-line system. This study presents a practical “cryogen-free” CO2 purification technique using electrical operation of a portable cryocooler for stable isotope analysis. This system can control the temperature of the cold trap in the vacuum line to an accuracy of 0.1 °C in a range from room temperature to the liquid-nitrogen temperature, which can be achieved in as little as ten minutes. Our “cryogen-free” cooling system offers releasing us from inconvenience of cryogen usage for stable isotope analysis, and also offers a new approach to the use of cooling methods in a number of fields of gas measurement, such as radiocarbon dating and the cryofocusing of volatile organic compounds.