Glycerol is a colorless, odorless, and viscous liquid. In laboratory settings, a 50% glycerol solution is a common mixture composed of equal parts pure glycerol and purified water. Its prevalence in science stems from a unique combination of physical properties that make it suitable for various applications.
Preparation and Physical Properties
Creating a 50% glycerol solution is a common procedure. The most common method is to prepare it on a volume/volume (v/v) basis by mixing equal volumes of high-purity glycerol and sterile, deionized water. For example, 50 milliliters of 100% glycerol is mixed with 50 milliliters of water. Using pure reagents is important to prevent introducing contaminants that could interfere with sensitive experiments.
The 50% glycerol solution exhibits distinct physical characteristics. Its viscosity is higher than that of water, a result of the strong intermolecular hydrogen bonding from glycerol’s three hydroxyl groups. This solution is also hygroscopic, meaning it readily attracts and retains water molecules from the atmosphere. A primary property is the substantial depression of its freezing point, as glycerol disrupts the formation of ice’s rigid lattice structure, allowing it to remain liquid at much lower temperatures.
Key Applications in Scientific Research
The primary application of 50% glycerol is as a cryoprotectant for the long-term storage of biological samples. When preparing bacterial cultures, cell lines, or enzymes for freezing, they are mixed with a glycerol solution to a final concentration of 15-25%. The glycerol prevents the formation of large ice crystals which can pierce cell membranes and destroy the sample. This interference with the freezing process ensures cell viability when stored at temperatures like -80°C.
Another use is in molecular biology for gel electrophoresis. Glycerol is a component of the loading buffer mixed with DNA, RNA, or protein samples before they are loaded into the wells of a gel. Because the glycerol solution is denser than the electrophoresis running buffer, it ensures the sample sinks to the bottom of the well. This allows for clean separation of molecules when an electric current is applied. The solution also helps stabilize proteins and enzymes, preventing their degradation during storage.
Proper Storage and Handling
Proper storage of a 50% glycerol solution is necessary to maintain its concentration and purity. It should be kept in a tightly sealed container at room temperature. An airtight seal is important due to its hygroscopic nature; exposure to air will cause it to absorb moisture and dilute the solution. For applications involving biological materials, the solution must be sterilized by autoclaving to eliminate microbial contamination.
While glycerol is recognized as safe and not a hazardous material, standard laboratory safety practices should be followed. This includes wearing gloves and eye protection to prevent direct contact. Although it is non-toxic, handling it with care ensures the integrity of the solution and the safety of the user. Following these protocols preserves the solution’s effectiveness for its scientific applications.