Labs invariably have a large variety of biological samples, reagents, and solutions that need to be properly stored, for the short or long-term. However, the optimal storage temperature for a given sample can vary depending on its intended use, suspension buffer, and duration. With limited lab space and operating costs, good storage practices are an invaluable asset to any lab. This cold storage guide will provide some helpful tips to follow.
Room Temperature (+20°C/+68°F)
Certain reagents and biological samples can be kept at room temperature, even for long-term storage. This primarily includes tissues that have been preserved in alcohol, formalin, or another fixative solution. These samples can be used for histology or anatomical analysis, but DNA and RNA extracted from these samples would be highly degraded and as such not usable. Any type of molecular biology analysis requires freezer storage.
Refrigerated Storage (4°C/40°F)
In laboratories, refrigerators are used to store routinely used biological reagents and buffers. This can include certain antibodies and enzymes, buffers for regularly performed experiments, as well as cell culture media. Freshly collected blood samples or tissue biopsies can also be stored in refrigerators for short periods, but should not be used for any long-term storage. Many research facilities also have cold rooms, that act as large refrigerators, allowing experiments and incubations to be done at 4°C far more easily.
Optimal for short-term storage, refrigerators are great for storing reagents that will quickly lose integrity with repeated freeze-thaw cycles, as long as they are used within a manufacturer’s recommended time frame. They can also be used to temporarily store tissues or even DNA/RNA while you wait for a piece of lab equipment to become available.
Freezer Storage (-20°C/-4°F)
Standard freezers are great for storing biochemical reagents and samples that are not stable at warmer temperatures. Found in most labs in the form of refrigerator/freezer combos, they are perfect for a lab with limited space. These freezers are typically used for more short-term freezer storage of samples that are routinely used, or needed for an upcoming experiment. This includes aliquots of peptides, antibodies, DNA, and RNA used for daily reactions, as well as tissues that have been suspended in the appropriate stabilizing solutions before freezing. However, more long-term storage will require an ultra-low temperature freezer.