Dynamic in-process examination of particle size and crystallographic form under defined conditions of reactant supersaturation as associated with the batch crystallization of monosodium glutamate from aqueous solution

Abstract

The use of in-process analytical techniques to give direct access to the processing parameters needed for the optimization of crystallization processes for new materials and to achieve process robustness for existing processes is presented. An integrated 2-L batch crystallization system incorporating advanced in-process analytical techniques (optical turbidimetry, ATR FTIR spectroscopy, ultrasonic spectroscopy, and X-ray diffraction) is described. Using this multitechnique facility, dynamic measurements of the onset of crystallization, supersaturation of the mother liquor, crystal size distribution of the particles produced, and pseudo-polymorphic form of the product crystals are obtained during the isothermal crystallization of monosodium glutamate monohydrate from supersaturated aqueous solutions. The results provide a useful insight into some of the mechanistic aspects of nucleation, growth, and breakage processes, as well as enabling the measurement of growth rate during a desupersaturation process. This development serves to enhance the understanding of crystal growth mechanisms at the molecular scale for industrial crystallization processes as carried out at a representative scale size.