Automated Sample Combustion and CO2 Collection System with IRMS for 14C AMS in Yamagata University, Japan

Abstract

Accelerator mass spectrometry (AMS) radiocarbon dating was introduced at Yamagata University (YU-AMS) in 2010. Development of sample preparation techniques began with the application of ¹⁴C AMS primarily aimed at microdose pharmacokinetics studies. We thus present ¹⁴C measurement results for an environmental sample. With the installation of this AMS system, we also installed a new automated sample production system, composed of an elemental analyzer, a glass vacuum line, and an isotope ratio mass spectrometer. With this system, it is also possible to measure stable isotopes (δ¹³C, δ¹⁵N, and δ³⁴S) of the sample gas using a mass spectrometer. To increase the amount of CO₂ gas introduced into a glass vacuum line, the gas mass flow introduced into the MS was reduced, and the resulting change of δ¹³C was monitored. The sample gas split ratio was changed to set the glass vacuum line (GVL): isotope ratio mass spectrometer (IRMS) to 5:5, 8:2, and 9:1, and δ¹³C was measured for each ratio. The results confirmed that there was no effect on the isotopic fractionation accompanying the change in the sample gas split ratio. To prioritize the use of gas in the production of graphite, the GVL:IRMS  ratio was fixed to 9:1 in the setup. These components are connected on-line, and up to 20 samples can be processed automatically.

DOI: 10.2458/56.16336