Progress towards traceable microwave moisture measurements

The design and basic principles of an experimental setup comprising a microwave-based moisture measurement system with a humid air generator is described. The combination of these two instruments implements a measurement technique similar in principle to that performed by a dynamic vapor sorption system. This technique enables a rapid determination of adsorption/desorption isotherms of moist samples implementing a secondary standard for on-site moisture measurements. Traceability to primary methods, such as loss-on-drying (LoD) or coulometric Karl Fischer (cKF) titration, can be achieved by preliminary calibration of the microwave resonances of a cylindrical resonator. We report preliminary tests of the performance of the whole system as used to determine the moisture content of tobacco.