Metastable glycine polymorph

Fines dissolution was used to produce the metastable glycine polymorph of the desired mean size during batch cooling crystallizationJ ... 

A systematic study of salting-out precipitation is carried out to obtain the operational limits within which this precipitation method can be applied for the production of fines (mean particle size <10 xm) with acceptable quality and productivity. The model substances glycine and sodium chloride are salted-out from their aqueous solutions by using ethanol as antisolvent. The main operational parameter is the initial supersaturation of the solutions. It is shown that the smallest particles can be produced at the limits of the metastability domain determined by three optional process parameters the initial solution concentration, the equilibrium solubility and the operational time. The product quality (crystallinity, polymorphic states, aggregation) and productivity considerably change with the operational conditions. 

It is today well accepted that a control of the heterogeneous primary nucleation can favor the formation of different polymorphs. In this context, the ability of membrane-based CTystalUzers to promote the selective formation of stable or metastable polymorphs on polymeric hydrophobic manbranes was confirmed by experimental tests on glycine with selective CTystalUzation of forms a and y (Di Profio et al. 2007a), on paracetamol with the possibility to disamtinate between the monocline stable form of... 

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