In-line monitoring of particle size and shape from image-based measurements

Within the pharmaceutical industry, particle size and shape distributions are crucial properties of crystalline particles produced in crystallisation processes. They determine the success or otherwise of processes such as granulation, suspension treatment and drying, all involved in the manufacture of the final pharmaceutical product. Some properties of the final pharmaceutical product such as dissolution behaviour are also influenced by the particle size and shape distribution of its ingredients. Therefore, crystallisation processes need to be controlled in order to produce particles with the desired attributes (size and shape). This in turn requires an accurate characterisation of the particle attributes during the crystallisation processes. Traditionally, particle size and shape are determined by means of off-line measurements. However, these techniques only provide information on the final state of the process and involve intermediate processing steps (e.g. sampling, dissolution, drying) that can alter the properties of the particles before the measurement. In recent years, a range of in-line techniques has been developed to obtain in-situ and real-time information on the state of the process in a non-disruptive manner.