Hello, Min. Lithium sulfate is a cryoprotectant at 2.0 M and sometimes even less (much lower than the concentrations needed for ammonium sulfate), so I would try replacing your ammonium sulfate with lithium sulfate, creating a cryoprotectant with 0.5-1.0 M KCl, 1.4-2.0 M LiSO4, at pH 7. You might need to transfer your crystals through a couple of intermediate drops.
Regarding the reservoir precipitation - is there any chance you could control the humidity of the area in which you're working? Even filling a couple of adjacent reservoirs with water might help buy you a few extra crucial seconds. Also, working in a cold room to harvest your crystals will help reduce the evaporation rate. Good luck! Best, Anna On Tue, Jul 10, 2012 at 9:28 AM, m zhang <mzhang...@hotmail.com> wrote: > regaentDear All, > > I am sure this question was discussed before. But I am wondering if anyone > got the same experience as I do. > I got a crystal out of condition with 1M KCl, 1.4M Ammonium sulfate at > pH7. I tried to use glycerol, ethylene glycol, 25% sucrose, paraton-N oil, > or ammonium sulfate itself: The problem is that all the cryo plus original > reagents in the reservoir precipitate the salts out. And more serious > problem is because of high salt in the condition, while I am trying to loop > the crystal, both the drop and cryoprotectant drop form salt crystals (not > sure it is KCl or ammonia sulfate) significantly and very quickly, that > cause my crystal dissolved. My crystal doesn't seem to survive paraton-N > oil. Does anyone here have similiar case? any suggestion will be > appreciated. > > Thanks, > Min >
