TEMPERATURE-VARIATIONS IN UPRIGHT MECHANICAL FREEZERS

We examined temperature deviations from the set temperature in specifi c locations, between-freezer temperature variability, and the effect o f defrosting on temperature deviation in a group of 15 upright mechani cal freezers, part of a biological sample bank of a large prospective cohort study, By using an Omega Type T Thermocouple Microcomputer ther mometer with the freezers set at -80 degrees C, the internal temperatu re (12 locations in each freezer) ranged from -90 degrees C to -43.5 d egrees C. Overall, internal temperatures tended to be appreciably warm er in the upper and front sections of the freezers. Upright front-load ing mechanical freezers, which are widely used in research laboratorie s throughout the world, may not be optimally suited to preserve human biological samples for long-term banking in epidemiology.