How long do primary antibodies last?

Primary antibodies are highly stable and resistant to a wide range of mild denaturing conditions. They will last anywhere from several weeks to a couple of years when stored properly as per the manufacturer’s guidelines. The exact shelf life will depend on the intrinsic properties of the primary antibody and the storage conditions.

When it comes to storing primary antibodies at optimum conditions, the two most important things to keep in mind are:

• Freeze/Thaw Damage – Antibodies are highly sensitive to repeated freeze/thaw cycles and will denature if exposed to these conditions, resulting in the formation of aggregates with a lower binding capacity.
• Antibody Concentration – Low protein concentrations can compromise the stability of the antibody and lead to protein losses. Increasing antibody concentrations mechanically should also be avoided as this too can result in loss of protein. When protein concentration is too low, adding BSA to purified antibody aliquots helps to increase concentration and improve stability. 

In addition, ideal storage conditions include:

• Freezing antibodies in small aliquots at -20°C. Aliquoting minimizes damage from freezing and thawing. 
• Storing antibodies in manual defrost freezers rather than frost-free freezers. Frost-free freezers have ongoing freeze/thaw cycles to reduce frost buildup, which is detrimental to antibodies.
• Storing antibodies towards the back of the freezer, which has minimum temperature fluctuations rather than on the freezer door.

Properly stored antibodies show minimum degradation over long periods of time while antibodies that are improperly stored can denature in a matter of hours. It’s best to always check the manufacturer’s product datasheet for specific storage recommendations.