Water sorption studies on rutin and the determination of moisture

Vapor phase water sorption studies were made on rutin of pharmaceutical grade and on highly purified rutin. The absorption and desorption curves for moisture at various relative humidities demonstrate the extremely hygroscopic nature of rutin. Several procedures for the determination of moisture in such a hygroscopic material were investigated. High temperature, vacuum, and an extremely dry atmosphere in the oven were found to be essential to insure complete drying. Special precautions were necessary to prevent rehydration of the samples after drying. A recommended procedure is described for determining moisture in rutin.