Biological samples are stored using a variety of methods, depending on the sample type, the length of storage needed, and the preservation method used. The primary methods involve temperature control, with different temperatures suited to different storage durations.
Short-Term Storage
For short-term storage, refrigeration at 4°C (39°F) is a common practice. This is suitable for many types of biological samples that need to be kept for a few days or weeks. Some samples may also require storage in a lab freezer at -4°C (25°F) for slightly longer-term preservation.
Long-Term Storage
Long-term storage of biological samples demands much lower temperatures to prevent degradation. This typically involves:
- Ultra-low temperature (ULT) freezers: These freezers maintain temperatures around -80°C (-112°F), significantly slowing down or halting enzymatic activity and preventing sample degradation. They are ideal for long-term storage of many biological samples.
- Cryogenic storage: This involves storing samples at extremely low temperatures, typically using liquid nitrogen (-196°C or -321°F). Cryogenic storage is used for the long-term preservation of highly sensitive samples, such as cells, tissues, and DNA. This method allows for near-indefinite storage.
Sample-Specific Considerations
The specific storage method also depends on the type of biological sample:
- Blood samples: Often stored refrigerated short-term or frozen long-term in special containers to prevent clotting.
- Tissue samples: Often frozen in ULT freezers or cryogenically stored for long-term preservation, sometimes embedded in paraffin for histological analysis.
- DNA/RNA samples: Typically stored frozen in ULT freezers or cryogenically to prevent degradation.
Proper labeling and meticulous record-keeping are crucial for effective sample management, regardless of the storage method employed.
Reference: For short-term storage, refrigeration or lab freezer storage at -4˚F is ideal for biological samples, while long-term storage requires ultra-low temperature (-112˚F) or cryogenic storage.
