I am having a hard time with freeze drying as the water extracts melts quickly during lyophilization. I do not know what to do or if something is wrong. The sample is purely a water extract of cymbopogon citratus. I did open the aircon in the room to maintain cool temp.
THE controlling factor in freeze drying is the vacuum level. The pressure in the dryer sets the sublimation point of the ice. Lower pressure = lower sublimation point.
Other factors will then affect the speed of drying - the heat of the system (or how hot the room is / sunny the room is - if you have a flask dryer) affect speed, more heat, the faster you go.
The limiting factor on the other side is how cold, and how powerful the condenser (desublimator) is. The condenser has to be colder thatn the sublimation point of the ice and has to have enough power to remove all the heat that is put in from your heat source(s).
If you can keep these in balance, you should get a successful drying experience.
There are other factors which can affect things, like what is in your sample, sugars, oils etc. and then there are external forces like other users of the equipment or electrical power fluctuations ...
A good overview can be found here:
https://www.spscientific.com/freeze-drying-lyophilization-basics/
Kind regards
Rob
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