Initial experiments with the in situ MAS approach on amine-functionalised silicas highlight the great promise of this approach. Two further approaches may be considered that employ NMR measurements on static samples. These can be applied to both liquid absorbents and solid adsorbents. In the "ex situ static" approach, CO2 is introduced to the sample in an NMR tube, either by bubbling CO2 through a liquid or by dosing CO2 into a solid with a gas manifold (Figure ). After the sample has equilibrated, the tube is sealed and taken for NMR experiments. A key advantage of this approach is that only conventional solution-state NMR spectroscopy equipment is required and that both liquid absorbents and solid adsorbents can be studied. A clear disadvantage is that MAS experiments are not possible. However, we do note that MAS is not required for liquid absorbents (where molecular motion averages out anisotropic interactions), nor for many solid adsorbents, where the considerable motion of CO2 (especially for physisorbed CO2, with only non-covalent CO2-adsorbent interactions) can lead to relatively narrow peaks for adsorbed CO2. This method has been used to study a wide range of materials including ionic liquids and metal-organic frameworks. Finally, the "in situ static" approach extends the above approach to directly dose CO2 gas into the static sample during the acquisition of NMR data (Figure ). This again has the advantage of enabling the capture material to be studied during operation, while also enabling a range of gas pressures and sample temperatures to be studied efficiently. One excellent example of these measurements explored the CO2 absorption pathways in a wide range of state-of-the-art aqueous amine CO2 absorbents. 50 CO2 gas was bubbled through the aqueous amine solutions inside the NMR magnet, and NMR measurements were recorded as a function of time. These experiments revealed the time-dependent uptake mechanisms, which varied significantly depending on the exact choice of amine. For example, monoethanolamine initially captures CO2 via the formation of ammonium carbamate, but at longer reaction times ammonium bicarbonate products began to dominate at the expense of the ammonium carbamates. A further excellent example used the "in situ static" approach to study mixed gas adsorption in a solid MOF adsorbent. The role of framework flexibility on the selectivity of gas adsorption was explored.