DSC studies on organic melting point temperature standards

A series of organic melting point temperature standards are available for which the liquefaction temperature has been determined by stepwise heating under near equilibrium conditions. The present work explores their use in the accurate calibration of DSC equipment. Two methods have been used, each of which has been shown to have advantages. In the first, a stepwise heating procedure has been adopted which is analogous to that used in calibrating the standards. The final step corresponds to the certified liquefaction temperature. In the alternative procedure the extrapolated onset temperature has been determined for zero heating rate. This work provides experimental confirmation that the extrapolated onset temperature at zero heating rate corresponds to the certified thermodynamic liquefaction temperature.