Preparation of nanomagnetic absorbent for partition coefficient measurement

Journal article

In this paper, we report a new method based on supercritical carbon dioxide (scCO 2) to fill and distribute the porous magnetic nanoparticles with n-octanol in a homogeneous manner. The high solubility of n-octanol in scCO 2 and high diffusivity and permeability of the fluid allow efficient delivery of n-octanol into the porous magnetic nanoparticles. Thus, the n-octanol-loaded magnetic nanoparticles can be readily dispersed into aqueous buffer (pH 7.40) to form a homogenous suspension consisting of nano-sized n-octanol droplets. We refer this suspension as the n-octanol stock solution. The n-octanol stock solution is then mixed with bulk aqueous phase (pH 7.40) containing an organic compound prior to magnetic separation. The small-size of the particles and the efficient mixing enable a rapid establishment of the partition equilibrium of the organic compound between the solid supported n-octanol nano-droplets and the bulk aqueous phase. UV-vis spectrophotometry is then applied to determine the concentration of the organic compound in the aqueous phase both before and after partitioning (after magnetic separation). As a result, log D values of organic compounds of pharmaceutical interest determined by this modified method are found to be in excellent agreement with the literature data. © 2006 Elsevier B.V. All rights reserved.

Authors: Tsang, S; Yu, C; Gao, X; Tam, K

• Journal: International Journal of Pharmaceutics
• Volume: 327
• Issue: 1-2
• Pages: 139-144
• Publication date: 2006-12-11
• DOI: 10.1016/j.ijpharm.2006.07.031
• ISSN: 0378-5173
• Language: English
• Keywords: Partition coefficient; Supercritical fluid; Magnetic nanoparticle; Porous; Magnetic separation