Formation of valine microcrystals through rapid antisolvent precipitation

Miroslav Variny, Sandra Alvarez de Miguel, Barry D. Moore, Jan Sefcik

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
91 Downloads (Pure)


In this work we have experimentally studied concentration effects on antisolvent precipitation of valine (an amino acid) from aqueous isopropanol solutions. Our experiments showed that the valine precipitation is very sensitive to both the supersaturation and to the water content in the final solution. Results from spectrophotometric measurements and supersaturation analysis showed that the crystal formation kinetics are strongly dependent on both mixing and concentration profiles in the early stages of the process, even though no visible change in the systems occurs immediately upon mixing with the antisolvent or subsequent dilution. Results from small-angle static light scattering measurements showed that the first visible crystals are of micron size and they grow only little over time, while their number increases gradually. Taken together, these experiments point to intermediate phase separation of (possible amorphous) precursors, being either very small nanoparticles or droplets with their refractive index closely matching that of the continuous phase, which subsequently assemble into micron size valine crystals.
Original languageEnglish
Pages (from-to)617-620
Number of pages3
JournalJournal of Dispersion Science and Technology
Issue number4
Publication statusPublished - 4 Apr 2008


  • antisolvent crystallization
  • valine
  • isopropanol
  • light scattering


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