A process analytical technology based investigation of the batch crystallization of sodium benzoate and para-amino benzoic acid

摘要

This paper focuses on the use of process analytical technology (PAT) tools for the detection of polymorphic transformations and for gaining an understanding of the behaviour of crystallization systems providing information for areas of improvements and designs of crystallization processes. Cooling and anti-solvent crystallization experiments are performed using the model compounds sodium benzoate (SB) in water and water/propan-2-ol (IPA) mixture and para-amino benzoic acid (PABA) in ethyl acetate (EA). PAT tools including the focus beam reflectance measurement (FBRM) and turbidity probe are used for the in-situ monitoring of the crystallization system, which detected polymorphic transformations. The combination of PAT approaches and solid state analytical (SSA) techniques, including X-ray powder diffraction (XRPD) and optical microscope, have led to the identification of a new channel sodium benzoate hydrate and the discovery of potential new forms of crystalline compounds of sodium benzoate (SB) and para-amino benzoic acid (PABA).