Reference
Storage and handling
Why lyophilised powder travels at ambient temperature, what changes once it is in solution, and what actually degrades a peptide.
A peptide in two different physical states has two different sets of requirements, and conflating them is the source of most storage confusion. Freeze-dried solid is robust. The same compound in solution is considerably less so.
Lyophilised powder
Freeze-drying removes the water that chemical degradation needs. What remains is stable at ambient temperature for the duration of normal transit, which is why shipping does not require active refrigeration and why an insulated envelope is adequate.
On arrival, refrigeration is the sensible default. For storage measured in months rather than weeks, minus 20 degrees Celsius or below is standard, and lyophilised powder tolerates freezing without difficulty. Keep vials in the dark. The enemy at this stage is moisture far more than temperature.
Always let a cold vial reach room temperature before opening it. Breaking the seal on cold glass pulls humid air in, which condenses inside the vial. That moisture is what degrades the powder, and the damage is not visible.
Reconstituted solution
Once diluent is added, the compound is in water and the clock starts. A reconstituted vial is refrigerated from that point, not returned to ambient storage. Bacteriostatic water extends the usable window considerably over plain sterile water because the benzyl alcohol suppresses microbial growth, but it does nothing about chemical degradation of the peptide itself.
Freezing a solution is possible but carries a specific hazard: repeated freeze-thaw cycling is one of the most effective ways to destroy a peptide. Each cycle concentrates solutes at the ice boundary and mechanically stresses the molecule. If a stock must be frozen, aliquot it into single-use portions first so that nothing is thawed more than once.
What degrades a peptide
| Cause | Applies to | Practical control |
|---|---|---|
| Moisture | Powder, severely | Warm to room temperature before opening |
| Heat | Both | Refrigerate on arrival, avoid leaving vials out |
| Light | Both | Store in the carton or a closed drawer |
| Freeze-thaw cycling | Solution, severely | Aliquot into single-use volumes |
| Mechanical shear | Solution | Never shake; swirl gently if at all |
| Repeated puncture | Solution | Aliquot rather than entering one vial many times |
Handling practice
- Wipe the stopper with a 70 percent isopropyl pad before every entry, not only the first.
- Label every reconstituted vial with compound, concentration and date. An unlabelled vial in a shared refrigerator is a vial you will eventually discard.
- Aliquot stocks that will be drawn from over a long period into smaller sterile vials.
- Dispose of needles into a rigid sharps container, not into general waste.
Every product page lists the storage condition for that compound, and the reconstitution guide covers the step between the two states.
Questions
Do lyophilised peptides need to be shipped cold?
No. Freeze-dried peptide powder is stable at ambient temperature for the duration of normal transit, which is why insulated packaging without active refrigeration is sufficient. Refrigeration matters once the vial reaches you and becomes necessary once the compound is in solution.
How long does a reconstituted peptide last?
Stability in solution varies by compound, by concentration and by diluent. As a general rule, a vial reconstituted with bacteriostatic water and kept refrigerated is worked with over a period of weeks rather than months. Plain sterile water, having no preservative, gives a much shorter window.
Can peptides be frozen?
Lyophilised powder tolerates freezing well and long-term storage is usually at minus 20 degrees Celsius or below. Solutions are a different matter: repeated freeze-thaw cycling is one of the most reliable ways to degrade a peptide, so a solution that must be frozen should be aliquoted first so each portion is thawed only once.
What actually damages a peptide in storage?
Moisture, heat, light and repeated temperature cycling, roughly in that order. Moisture is the reason a cold vial should reach room temperature before it is opened, since condensation forms on cold glass the moment the seal is broken.
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