In principle the measuring method is based on the reaction of gaseous water and a reagent, which is calcium hydride. This unique procedure is what makes it a water-selective measuring method.
The sample material is weighed and placed into a sample tray. The sample tray itself is part of an integrated reactor within the HydroTracer. A heater warms the sample – temperatures between 50 °C and 210 °C are freely selectable.
The water evaporating from the sample reacts with the reagent in a cooled area and water is transformed into hydrogen. Other volatile substances will condense at the cooled surfaces within the vessel. The concentration of hydrogen gas is measured. It is a measure for the amount of water in the reactor.