Laboratory freeze dryers preserve samples by freezing the material and then allowing sublimation to occur. This water-removal process is also known as lyophilization. Typically, laboratory freeze dryers are used in clinical, medical, and pharmaceutical applications. They are also used in the food processing and biotechnology industries. Some laboratory freeze dryers comply with regulations from the U.S. Food and Drug Administration (FDA), or meet the FDA’s Current Good Manufacturing Practices (cGMP). Others are rated for clean room applications, or use a cooling method that is free of chlorofluorocarbons (CFCs). Water cooled, Teflon coated, and double-chamber laboratory freezer dryers are also available.
Rotary evaporators are laboratory freeze dryers that are used in many chemical and biochemical applications. They are used to preserve perishable materials, and to make materials easier to transport. Typically, freeze-dried materials are sealed to prevent re-absorption of moisture. Like some other types of laboratory freeze dryers, rotary evaporators can be used to lower the boiling points of liquids, including solvents. They are very effective at removing most organic solvents through an extraction process. Often, the leftover materials are then removed with a high-vacuum line. Rotary evaporators and related types of laboratory freezer dryers may also have an integrated microprocessor to maintain conditions with the chamber or chambers.
Manifold freeze dryers and laboratory tray dryers are basic categories of laboratory freezer dryers. Manifold laboratory freeze dryers are compact, benchtop units that are used for light to moderate sampling requirements. This type of laboratory freeze dryer is often available with the choice of a condenser temperature, manifolds, and many other accessories. Tray laboratory freeze dryers are also available. Laboratory tray dryers consist of a cabinet that contains trays, which is connected to a source of heated air. The air enters the bottom of the chamber below the trays and rises. Air flows through the material and out an opening at the top of the chamber.
Performance specifications for laboratory freezer dryers include condenser temperature, condenser capacity, condensing rate, number of ports, number of shelves, and maximum vacuum. Condenser temperature is the operating temperature of the condenser, the laboratory freeze-dryer component which transfers unwanted heat out of the system. Condenser temperature determines the temperature at which the freezing process occurs. Condenser capacity is the amount of water that can be removed by the condenser before defrosting. Condensing rate is the rate at which water can be removed from the sample. Some laboratory freeze dryers have manifolds to allow for the simultaneous freeze-drying of a number of samples. This specification is the number of ports or vials that can be used for freeze-drying samples.