Vapor pressure and water activity measurements of saturated salt solutions made with D2O at 20°C

The water activity (aw) values of 10 saturated salt solutions made with D2O were measured in this study at 20°C: MgCl2, K2CO3, Mg(NO3)2, KI, NaCl, KCl, ZnSO4, BaCl2, KNO3, and K2SO4. These salts were selected because they represent a wide range of water activity values, from approximately 0.33 to 0.98. The aw values were measured using two methods: (1) a vapor pressure manometer, and (2) an electronic chilled-mirror (AquaLab) instrument. The aw values obtained by the manometer method were slightly, but consistently, higher than the aw values obtained by the electronic chilled-mirror instrument. The aw values of the saturated salt solutions made with D2O (as measured by both methods) were also slightly, but consistently, higher than the aw values of the same saturated salt solutions made with H2O at 20°C. ©