I have been able to successfully separate D8/d9 with CPC. A solvent system consisting of heptane/meoh/h2o(20mmol/liter of hpBcyclodextrin) the aqueous phase is stationary as the cyclodextrins improve the chiral selectivity, this phase is 70:30 favoring meoh. Heptane is mobile. This works well and although it doesn’t completely resolve the two, you can get 80% or better yield of d9 free D8 depending on your starting material. Unfortunately, unless you’re grinding on a kromaton 10L or 20L unit with membrane recovery, I don’t think CPC can be justified with the current market value of D8.
The one issue I am seeking some advice on is the following: although the stationary phase holds back most of the cyclodextrins a small amount are eluting through and I need a way to separate them from the oil, any ideas? Perhaps a certain filtration media?