Seed-Assisted Effects on Solution-Mediated Phase Transformation: A Case Study of l-Histidine in Antisolvent Crystallization

In this study, the effects of crystal nucleation growth on subsequent solvent-mediated phase transformation experiments of L-histidine (L-his) in antisolvent crystallization were performed at 298.15 K. The unexpected acceleration of the overall transformation rate in antisolvent crystallization with solution-mediated phase transformation was found for a methanol volume fraction of 0.35 < x(2) < 0.60. Interestingly, concomitant polymorphs were obtained for a methanol volume fraction of 0.30 <= x(2) <= 0.65 in antisolvent crystallization, whereas only form B was observed for other volume fractions of methanol, which indicated that the concomitant polymorphic phenomenon was the main reason for the accelerated transformation rate in antisolvent crystallization. Furthermore, seed-assisted experiments and suspended solution-mediated phase transformation experiments were designed to uncover the role of the nucleation of form A accompanying with form B in the subsequent transformation process.