Every researcher should know and understand how to handle the various types of peptides they will be dealing with. If you get your peptides from verified vendors, then the shipping will always include a user manual from the manufacturer, and it is highly recommended to read it, to ensure that you understand the specific requirements to handle that particular peptide.
To give you some insights, here are guidelines on how to handle and store some of the peptide types:
Guidelines for lyophilized peptides
The stability of every peptide is unique, and will be contingent upon its sequence. For lyophilized peptides, the recommended temperature in storage, should be around -20 degrees Celsius, and away from bright light. These peptides will remain stable for several years, if kept under these conditions, but it should be noted that there are certain amino acid residues in the peptides, which may affect long-term stability, if kept under these conditions.
Regarding peptide sequences containing Met, Trp, or Cys residues, they have a tendency to become oxidized, and as such, they should be stored under anaerobic conditions, to ensure their stability. Peptides with Glu, Asp, Arg, His or Lys, have a tendency to absorb moisture from the atmosphere, and they should thus be stored inside of a tight vial, within a desiccator.
Guidelines for peptides in solution form
Peptides in solution form usually have a very limited shelf-life. Additionally, these peptides are susceptible to bacterial degradation, and so storage in solution form, is never a good idea in most cases. However, if storage can’t be avoided, then sterile buffers at pH 5 – 6 should be used to dissolve the peptides, and then the solutions should be divided into aliquots, before being stored at a temperature of below -200C. Freeze-thaw cycles should be avoided with these aliquots, since they may cause the peptides to become deteriorated quite quickly.