Preparation of nanomagnetic absorbent for partition coefficient measurement.
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, logD values of organic compounds of pharmaceutical interest determined by this modified method are found to be in excellent agreement with the literature data.
Tsang
Shik Chi
SC
The Surface and Catalysis Research Centre, School of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK. s.c.e.tsang@reading.ac.uk
Yu
Chih Hao
CH
Gao
Xin
X
Tam
Kin Y
KY
D020003:1-Octanol / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013818:Thermogravimetry; D014867:Water / Q000737:chemistry
D005290:Ferric Compounds; D014867:Water; D002245:Carbon Dioxide; C000499:ferric oxide; D012822:Silicon Dioxide; D020003:1-Octanol