Dynamic vapor sorption instrument

Water sorption-desorption isotherms can be carried out by using thermobalances. Now specific instruments allow to measure water sorption-desorption isotherms at different constant temperatures (e.g., dynamic vapor sorption instrument (DVS), Surface Measurement Systems Ltd., Monarch Beach, US). 

Penner EA (2013) Comparison of the new vapor sorption analyzer to the traditional saturated salt slurry method and the dynamic vapor sorption instrument. M. Sc. dissertation, University of Illinois... 

The water-sorption experiments were carried out in a dynamic flow vapor sorption apparatus (Model SGA100, VTI Corporation, Hialeah, FL). Samples of the two polymorphs were placed in the instrument s sample chamber and their moisture uptake as a function of relative humidity (RH) was measured. Water-sorption isotherms for both polymorphs were carried out imder the temperature conditions of 20, 25, 35, and 45°C. The amoimt of sample used for an analysis depends on the sample s tendency to pick up water. If the sample is highly hygroscopic, about 2-5 mg is sufficient for the test, but if the sample is nonhygroscopic, a larger mass is needed, about 25 mg or more. For this study, water-sorption isotherms for both polymorphs were carried out using the flow system and a sample size of about 50 mg. 

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