Purified hormones that have been lyophilized and sealed under vacuum or with dry nitrogen are very stable when stored at or below -15°C, generally showing little loss in activity even after 5 years or more of storage. Still, certain steps will help ensure the longest possible shelf-life of the product.
- The product should be stored frozen at or below -15°C in a non-cycling freezer.
- The material should be equilibrated to ambient room temperature prior to opening the vial. If a weighed quantity of dry powder is to be removed, the vial must be opened in a dry room. If it is to be used repeatedly, the powder should be subdivided into aliquots, resealed, and stored at or below -15°C.
NOTE: It is very difficult to aliquot hormones by dry weight. To improve consistency, it is suggested that the entire vial be resuspended in an appropriate buffer, aliquoted by volume, then stored frozen.