HomeLab & Science NewsArticles5 questions to ask before buying a freeze dryer

5 questions to ask before buying a freeze dryer

Jenny SprungBy Jenny Sprung, Senior Application Specialist
On Thursday, January 08, 2015
In Articles

Lyophilization (or freeze drying) is commonly used as a solution for long term storage or as a sample prep step. This article will help you determine which is the best freeze dryer for your needs. 

Ask yourself the following questions when choosing a freeze dryer:

What is the total amount of moisture (in liters) you want to remove? 

  • For example, if you are processing 6L of total liquid a 6L unit or larger is required (in fact, at least 50% extra volume is recommended). Also, some drying chamber accessories (such as the Stoppering Tray Dryer) only work with a 6L or larger base unit regardless of sample size.

What type of samples are you processing?  Each component is important, so think about all of the solvents and solutes that will be a part of the total samples.  

  • Proper freeze drying requires a temperature differential of 15 to 20 degrees between the samples’ freezing point and collector chamber. Without the collector being colder than the freezing point, the sublimated matter will bypass the collector and enter the vacuum pump, causing damage.
  • If samples are acidic or can cause damage to the stainless steel coils, PTFE coating is recommended to prevent rust and holes in the collector.

The following chart shows some common freezing points of solvents and recommended collector temperature:

Suggested temperature for solvents lyophilization chart

What format are your samples in? Make sure your accessories match up with the format of your samples.

Is stoppering under vacuum for long term storage or transport required?

  • The Stoppering Tray Dryer or Triad are the two options if large quantities are processed.  Both units will do all steps of the freeze dry process; pre-freeze, primary dry, and secondary dry.  Once secondary drying is complete, the units can stopper samples under vacuum.
  • The Mini Stoppering Chamber can be used along with a port-type freeze dryer for smaller quantities. 

A vacuum pump is required. What kind of pump should be selected based on your sample type?

  • For standard aqueous based samples, a general rotary vane pump will work.
  • For acids or solvents, a hybrid type pump would be recommended. 
  • Make sure the pump meets the minimum specifications required for your lyophilizer.

Contact me if you have any questions!

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