By Adam Christensen
Ultra-low temperature (ULT) freezers provide the extremely cold environment needed to preserve biological samples during long-term storage in research laboratories. The samples, which may include cancer cells, stem cells, cord blood, T-cells, or organ/tissue, are priceless to researchers and irreplaceable if a temperature excursion causes damage. While ULT freezers can operate in the range of -86 to -40 degrees Celsius, the set point is typically -80 or -70 degrees Celsius,1 depending on the cell type. Temperature uniformity, from top to bottom and back to front of the unit, is important to ensure the viability of samples, some of which are stored for several years. But stability and reliability of the ULT freezer is impossible without proper use and preventive maintenance (PM). The following criteria will help a lab manager train users and maintenance staff on protocols to keep the ULT freezer running optimally and reliably for cell preservation. In the long run, these recommended practices also increase the longevity of your unit — and your return on research investment.