[Chompou]

I want to make a phase diagram of 2 compounds (carbamazepine and nicotinamide, melting point 188 C and 128 C respectively). I use DSC( Differential Scanning Calorimeter) to determine the melting point of different Carbamazepine and nicotinamide compositions.

The problem is nicotinamide evaporates easily from 140 degree Celcius. The liquidious temperature I measured is therefore not the same as the begin composition because some of nicotinamide already change into gas.  What is the best way to measure the melting point of evaporative compound/ or how to measure correct composition of the melt?

Thank you for your help