Comparison of two melting range analysis methods with lactitol monohydrate

Abstract

In pharmacopoeia, the melting point is determined by a standard method with a melting point instrument. The melting point can also be determined with differential scanning calorimetry (DSC). In this study, the standard method and DSC method are compared for determining the melting range of lactitol monohydrate. The effect of initial temperature, grinding, and drying on the melting range of different lactitol monohydrate samples was studied by a melting point instrument. The melting point and melting enthalpy of the stable form of lactitol monohydrate was identified by DSC. The statistical analysis of the results is based on a t-test. All studied variables had a small effect on the melting range. Repeatability of these two methods was calculated. The intermediate precision was also determined for the measurements of the melting point instrument. The melting range of lactitol monohydrate taking into account the intermediate precision is 94–100°C determined with a melting point instrument. The melting range determined with the DSC is according to these measurements 93–99°C and the melting enthalpy is 58.5±1.0 kJ mol −1 .