PACKAGING & SHIPPING
New England Biolabs ships its products in plastic foam (polystyrene)
containers with gel ice packs and recommends that its distributors do the
same. Gel 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 2°C to 8°C for more
than 24 hours. Testing at NEB has shown that there is no difference in
activity and stability between enzymes that are shipped with gel ice packs
and enzymes shipped on dry ice.
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
away 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 shipped 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.
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. If this shipping procedure posed any risk to our
products, we would change the procedure immediately.