Comparison of two melting range analysis methods with lactitol monohydrate

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 rang e of different lactitol monohydrate samples was studied by a melting point instrument. The melting point and melting enthalpy of the stable form of la ctitol monohydrate was identified by DSC. The statistical analysis of the r esults is based on a t-test. All studied variables had a small effect on th e melting range. Repeatability of these two methods was calculated. The int ermediate precision was also determined for the measurements of the melting point instrument. The melting range of lactitol monohydrate taking into ac count the intermediate precision is 94-100 degreesC determined with a melti ng point instrument. The melting range determined with the DSC is according to these measurements 93-99 degreesC and the melting enthalpy is 58.5 +/- 1.0 kJ mol(-1). (C) 2001 Elsevier Science B.V. All rights reserved.