Solutions of Streptozotocin will spontaneously give off NO gas at room temperature. This NO release is slowed, but not completely stopped at -80°C, and the rate of NO release is also impacted by the solvent used (for example, dissolving Streptozotocin in buffers that contain sodium speeds up NO release).
 Since it does not seem to be possible to completely stop the NO release when streptozotocin is in solution, and the NO donor function is critical to the majority of experimental applications, we recommend that customers make solutions only immediately before use.
 
Note: since streptozotocin is often used to treat animals, the requirement that solutions be made immediately before use can be overwhelming for some users. Therefore, we generally suggest that the material be initially dissolved in ethanol, aliquoted into single use amounts, and then the alcohol evaporated off to produce dry aliquots. NO loss is minimized by doing this procedure with the material on ice, and carrying it out as quickly as possible. The individual dry aliquots can then be easily dissolved immediately before use.

Datasheet / MSDS