Abstract
In this paper, the transformation water activity of L-Phenylalanine (L-Phe) in a methanol-water solution at a different temperature was measured by the ternary diagram. The influence of water activity on the transformation temperature and on the transformation rate was investigated. The solubility of the metastable form of different water activities was estimated based on the thermodynamic equilibrium and the results showed that the anhydrous L-Phe can be synthesized at room temperature by decreasing water activity, the transformation rate from monohydrate to anhydrate was enhanced with the increase of water activity. The predicted solubility value is in good agreement with the experimentally obtained. Meanwhile, tailor-made additives were applied into the system as to investigate the transformation behavior of L-Phe. Their mechanism was proposed based on the Langmuir model fitting. The result manifested that the addition of L-Trp/L-His amino acid in the L-Phe solution decelerated the transformation rate. When the concentration of L-Trp amino acid reached 0.7 × 10−4 mol/mL, the transformation behavior of L-Phe can be fully impeded, and the transformation behavior can be partially inhibited with the addition of L-Trp at 313.15 K or with the addition of L-His at 283.15 K/313.15 K.
Highlights
Hydrate is an ordinary pharmaceutical polymorph [1,2,3], 57% of pharmaceuticals can form hydrate polymorphs
The transition water activity at 293.15 K, 297.15 K and 302.15 K were measured and were 0.921, 0.948 and 0.982 respectively, which increased with temperature, obtaining the ternary phase diagram of methanol/L-Phe/water at that temperature
The results of the transformation behavior of L-Phe showed that anhydrous L-Phe was substantially completely converted into L-Phe+ H2 O
Summary
Hydrate is an ordinary pharmaceutical polymorph [1,2,3], 57% of pharmaceuticals can form hydrate polymorphs. Much attention has been focused on the regulation of polymorphism and various methods have been used to control the polymorphism crystal form, such as temperature, additives and the time of crystal transformation. Much attention has been focused on the regulation of polymorphism and various methods have been used to control transformation, such as temperature, additives and solvents. The method of regulating water activity to realize the production control of hydrated polymorphism due to low contaminate is put forward in this paper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
