Versatile high-pressure gas apparatus for benchtop NMR: Design and selected applications.

A simple, yet highly versatile setup is presented for benchtop NMR analyses of gases at high-pressure. It consists mostly of commercial parts and includes multiple safety features while maintaining a small size to fit into a 1.20 m wide fume hood. Pressures up to 200 bar can be adjusted independently of the sample gas-bottle pressure in a matter of seconds. Mixtures of multiple gases can be produced in situ in a mixing chamber, which also serves to adjust the pressure. The high-pressure hardware and benchtop NMR spectrometer have been tested for long-term stability and repeatability of the measurements. The versatility of the setup is demonstrated by analyzing hydrocarbon-gas with attention to linewidths as well as their 1H relaxation times, by improving the resolution of 1H NMR spectra from solid polymers with pressurized CO2, and by visualizing the ingress of gaseous and supercritical methane into liquid benzene.