Measuring absolute gas amounts with gas chromatography by using a novel setup for pressure based gas control

The characteristics of the gas itself, such as its volatility, compressibility, or weight, often complicate the process of feeding gas into a measuring system, such as a gas chromatograph. This is particularly relevant when quantifying individual gas components. While it is possible to inject gas with syringes, this method has several disadvantages, such as gas tightness and syringe and gas volume, especially for small gas quantities. Therefore, there is an urgent need for a simple, reliable, and improved method of gas injection into a measuring device. This study describes the development of a novel gas injection system that reliably and contaminant-free injects gas into gas chromatography (GC) instruments and other gas-related devices. The system consists of an injection unit, a vacuum system, and a loop assembly, and it connects directly to the corresponding device. Sample gas can then be introduced directly into the evacuated injection system and delivered to the measuring device. The system has been validated using a range of configurations and has undergone extensive testing. Additionally, two applications are presented to demonstrate the system's wide range of potential uses. Notably, the setup enables a contamination-free gas supply from battery pouch-bag cells. For this configuration, an adapter assembly was required for the pouch-bag cell and was integrated into the battery cell. Additionally, it is demonstrated how the setup can be used to determine the gas composition of a thermal decomposition reaction. This setup is a new, platform-independent option for introducing gas into a low-pressure environment and connecting it to devices without causing contamination. Reduced pressure enables multi-point calibration with a single reference or calibration gas mixture, which is pressure-dependent. Additionally, the integrated loop technology allows for the quantitative calculation of gas concentrations. Errors in calculating the amount of substance are less than 10-20%, even with flexible pouch cells.