New England Biolabs ships the majority of its products in plastic foam (polystyrene) containers with wet ice packs. Wet ice packs are kept at -20°C for at least 72 hours prior to shipment and the polystyrene boxes are tightly sealed. Tests have shown that products shipped under these conditions will stay at or below 4°C for more than 36 hours for our overnight shipment boxes and for more than 96 hours for our over-weekend shipment boxes. Testing at NEB has shown that there is no difference in activity and stability between enzymes that are shipped with ice packs and enzymes shipped on dry ice.
We have used these shipping conditions for the 40+ years that we have been providing DNA restriction and modifying enzymes and related products to the scientific community.
Some of our products are shipped at ambient temperature - find out more here.
All of our enzymes are provided with tubes of optimum reaction buffer. These buffer solutions and the ice packs are frozen to -20°C before they leave our facility, however they may have thawed upon arrival at their final destination. This is no cause for concern with our wet ice shipments since buffer integrity is maintained.
Storage of New England Biolabs Products
While New England Biolabs recommends storage of its enzymes at -20°C, exposure to higher temperatures (4 to 10°C) during shipping does not pose any risk to the enzymes. In fact, during the purification process (up to 3 weeks) enzymes are maintained at these temperatures as they are purified from proteases and other contaminants which might interfere with their stability. Furthermore, each enzyme is shipped in a specific storage buffer which has been optimized for long-term stability.
NEB enzymes are stored in buffered 50% glycerol and remain liquid at temperatures down to -35°C. If these enzymes are stored at colder temperatures (for example, in the presence of dry ice) the products will freeze. Proteins subjected to repeated freeze/thaw cycles may lose activity.