If you accidentally get h2o in your fasa container, i would put it uncapped in a larger airtight container with a wide mouth on a DEHYDRATED epsom salt bed to dry.
Ideally, a pyrex dish, and a large flat seal-able container would work best for surface area reasons, but thats for another day. Non electronic/heat vacuum sealable bags, mgso4 in a permable mesh enclosure (like silica packets), underneath the pyrex dish. That would dry the hydrated solvent real good one would think. Just be careful with electronic, heat, or even mechanical mechanisms in your vac pump. A spark/ignition source can come from anywhere.
put a few oz's of dried epsom salts down, and then place the vessel with your fasa & acetone/fasa & limo/or fasa and xylene in, only sealing the outer jar. Since you want the very dry air to make contact with the hydrated binary solvent with fasa/x np or acetone. Leave it in a dry, dark, and not cold, but not hot place.
Seal the top and leave it overnight, make sure its AIRTIGHT. Remove the inner vessel, cap immediately in a airtight container, and freeze it if its acetone/fasa. IDK if i would do that with limo or xylene, as that might crash out all the fumaric acid too.
You could always bring the inner vessel without breaking the outer vessel seal before bringing it back to room temp (should do anyway to prevent condensation from warmer air/cold liquid), and the excess fumaric acid would dissolve again.
I've never frozen fasa, so i couldn't really say though.
