Temperature Variations in Chest-type Mechanical Freezers

Abstract

A recent report described temperature variations within upright mechanical freezers set at −80 °C (1). The range of internal temperatures was great, with the warmest specimen being at −43.5 °C and the coldest at −90 °C. These findings suggested that it might be useful to study the temperature variation within horizontal chest-type freezers. In 1974, blood samples were obtained from 25 802 adult volunteers in Washington County, Maryland. In 1989, an additional 32 320 samples were obtained in a similar project. The separated serum samples from each project were stored in mechanical chest-type freezers set to hold an interior temperature of −73.3 °C. For subsequent studies, sera from newly diagnosed cancer cases and from healthy controls have been assayed for a variety of micronutrients, hormones, or antibodies. In this study, serum samples were stored in 5-mL plastic Nunc tubes (Nunc), 100 in a cardboard box with the boxes stacked …