I perform DSC, temperature -60 to 120C, of my spray dried powder sample. But i cant set the base line which transition 1 or 2 will be the glass transition temperature Tg. When i set to base line i got onset, endset and midpoint temperature. Which one is the Tg. In Gordon Taylor model, Tg, Tgs, and Tgware the glass transition temperatures of the mixture, solids, and water, respectively,xw is the mass fraction of water, and k is the Gordon-Taylor parameter, how can i predict. specially k value . my sample solid about 96% water 4%.