Hi Chen, I had a similar condition before (reservoir solution with 10% dioxane) and an oil-based cryoprotectant (66.5% w/w paraton-N, 28.5% paraffin oil and 5% glycerol) worked for me. Please check this paper out: http://scripts.iucr.org/cgi-bin/paper?wd5052
In addition, have you tried cryoprotection without removing the sealing membrane? I did it by punching a hole on the membrane with a needle, taking away the reservoir solution with a syringe, and adding the cryo solution to the reservoir. You can then wash the crystals withy the cryo solution, seal the membrane and let it equilibrate before looping the crystal. Also I think it better to change the reservoir solution in small steps (like from 30% dioxane --> 25% dioxane plus 5%EG --> 20%dioxane plus 10%EG ... until dioxane is 0%). To be honest I never tried it with a dioxane-containing condition, but it worked pretty well with a condition containing 20% isopropanol.
