A Benchtop Cold Box for Biochemistry In the course of research work i t was necessary t o conduct refrigerated experiments in an open laboratory adjacent t o other equipment. The development of a portable cold box solved this problem and also became a useful implement for instructional purposes. Cold room projects can pose a serious prohlem in teaching biochemistry. While the isolation of proteins and organelles requires low temperature, conventional research cold rooms are unsuited for class use. They are inconveniently sited and are too small and too difficult to enter and leave. Besides size and traffic problems, the refrigeration units cannot replace the cold air lost mechanically or cope with the human heat load fast enough. A good alternative would be a cold unit which could he temporarily placed on student lab benches as the need arose, as, for example, in grindingand centrifuging homogenates, ammonium sulfate fractionation, dialysis, gel and DEAE chromatography, and electrophoresis. By combining features of the glove box and supermarket display case, we have designed a portable cold box that weighs about 1W lh, fits on a standard lab bench, provides good workingvisibility and accessibility, and accommodates conventional equipment, fraction collectors, etc. (Fig. 1). The figures and description show the important details. There are many possible substitutions and the designation of a particular product does not imply an absolute requirement or an endorsement.
Figure 3. Cross-section of box
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Construction.
The walls consisted of a laminate of %-in. exterior grade plywood lined with 1-in. Styrofoam insulation whose inner surface was covered with 'la-in. exterior grade plywood. The Styrofoam was bonded to both wood surfaces by Styra-Band Adhesive (3C Co.). Frost-free doors and windows were constructed from twin layers of ?!-in. Plexiglas separated by a %-in. air space. The plastic panels and box walls were constructed as an interlocking system and the wallsections in contact with the oanels were covered with !&in. soonee rubber 1Armstrone co .:~rmafler insulation) 1~$:2). T'he window and ton door Figure 1. Cold box in use screws passing through oblong holes in the plastic so that the
with Freon 12. Moisture from the blower coil was ~ n v e n i e n t l ydrained into a bottle. Temperature wasUregulatedby a hydraulic action temperature control (White-Rodgers). In the fall of 1974 these mechanical parts cost about $125 and their professional installation about $100. The specifications were such that starting from room temperature the box cooled to 4 T in about 30 mi". A floor temperature of 5-6'C was held indefinitely with the bottom door remaining open. Department of Microbiology a n d Biochemistry University of Vermont Burlington, 05401
David Raeusen Lee White
Volume 53,Number 10, October 1976 / 635
