I am trying to freeze-dry samples made of 0.1mL water and 0.5mL methanol. My freeze-drier only reaches -55C and methanol freezes at about -98C so the samples are never actually frozen. The vaccum seems to generate clear fumes everytime I turn it on. Could this mean some methanol is reaching the vacuum machine and damaging it or, at least, being potentially toxic to the ones around in the lab?
You can not have more methanol than approx. 60 % vol/vol for the methanol / water ratio (cf. link below), if indeed you want to freeze-dry the sample wetted with the methanol-water mixture at -55 ºC. Otherwise, you need to further decrease the temperature, somehow. Some possibly useful references on freeze drying were signalled at:
https://www.researchgate.net/post/Does_anyone_know_of_a_good_review_paper_on_freeze_drying
http://www.methanol.org/Technical-Information/Resources/Technical-Information/FreezingPointsMethanol-WaterSolutions.aspx
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