The main purpose of low temperature storage is to avoid further biological activity i.e. genetic or enzymatic. At reduced temperature processes are dramatically slowed down and comes to a complete stop at -131°C which is called water transition temperature.
In other words the storage temperature is chosen according to the activity level of sample as well as the expected storage period.
In general terms the following guidelines are used in the medical/pharma segment:
- Short period storage within weeks can be done at -18 to -30°C using mechanical freezers.
- Medium period storage within 1-3 months can be done at -30 to -50°C using mechanical freezers.
- Long period storage within 6-12 months can be done at -50 to -80°C using ultra low mechanical freezers.
- Extended period storage for years can be done at -131°C or below using special cryogenic freezers or liquid nitrogen
The process of freezing down and storing samples is done by using mechanical freezers as well as special storage tanks using LN2 (liquid nitrogen) used within the following medical/pharma applications:
- Stem cell storage
- Cord blood storage
- Cell line storage
- Other biological material storage
In the food segment FDA and HACCP regulations are controlling the specific requirements for storage of food products.
The critical parameter during storage is of course temperature but often also humidity is monitored.
Validation must be carried out regularly to ensure that a low temperature cabinet or cryogenic freezer is capable of accurate and repeatable performance. TrackSense® Pro and the battery used are specified down to -30°C – with TrackSense® Pro-X even down to -80°C. This together with a unique battery management system and design of logger and flexible sensors makes them highly suitable.