Gravimetric CO2 adsorption measurements were conducted on a Hiden IGA-001 microbalance. Samples (30-50 mg) were activated by purging with CO2 at 70 mbar at 40°C until the sample weight stabilized. Isotherms were then measured under flowing CO2 regulated by a mass flow controller and back pressure regulator. Equilibrium was determined at each pressure step using an internal fitting algorithm in the instrument control software. Buoyancy corrections were then applied to the final equilibrium weights using known densities of all components in the sample and counter weight chambers from gas densities calculated using REFPROP software from NIST. An additional minor correction (<5% of the adsorbed mass at 18 bar) was also applied to the final equilibrium sample mass at each pressure point to account for the small change in buoyancy force which results from volume expansion of the solvent during CO2 adsorption. The volume expansion of the solvent was estimated from the mole fraction of CO2 adsorbed using the molar volume of liquid CO2 at 25°C (density of 0.7105 g/mL, 16.15 mol/L). Shiflett and Yokozeki employed a similar system to measure equilibrium CO2 absorption in ionic liquids and estimated the relative uncertainty in CO2 pressure to be 0.008 bar and in mole fraction CO2 solubility to be less than 0.006. Water vapor adsorption measurements were conducted using an inline humidifier which was held at 23°C with a sample temperature of 25°C with N2 as the carrier gas. The relative humidity in the gas stream was controlled by blending dry N2 with humidified N2 prior to entering the sample chamber with the gas ratios set using mass flow controllers. Relative humidity in the sample chamber was then calculated from the sample chamber temperature and vapor pressure of water in the humidifier assuming complete saturation of the carrier gas. Final equilibrium loading of water vapor in the sample was determined by fitting the water adsorbed sample mass to an asymptotic model using OriginPro® (v 9.1) curve fitting software.