Glossary: Gravimetric

Pertaining to the measurement of weight or weight change. The first gravimetric sorption analyzers were called McBain spring balances and the weight change due to sorption was measured manually from the extension of a quartz spring. Modern automatic gas and vapor sorption analyzers like the IGA use ultra-sensitive electronic microbalances to directly measure weight change due to sorption and this is corrected for the buoyancy effect to give the mass uptake isotherm. In the absence of sorption, a gravimetric analyzer can also be used as a densitometer to measure the equation of state of the sorbate or the density of the sample.