Storing peptides: powder, solution and cold chain
A peptide does not fail with a bang. It slowly loses its shape, and you usually cannot see that in the powder. That makes storage rules more important here than with most substances.
Three things break a chain down
- Water. Hydrolysis cuts the peptide bond. That is why dry powder is far more stable than a solution.
- Heat. The warmer it is, the faster every chemical reaction runs, the unwanted ones included.
- Oxygen and light. Amino acids carrying sulphur or a ring are especially sensitive. Glutathione is the clearest example.
The three work together. A vial left open on a windowsill gets all three at once.
Rules of thumb by form
| Form | Where | Roughly how long |
|---|---|---|
| Powder, unopened | freezer, dark | months to years |
| Powder, unopened | fridge | months |
| Powder, in transit | room temperature | a few days is no problem |
| In solution | fridge, dark | days to a few weeks, depending on the substance |
| In solution | room temperature | short; the longer the chain, the shorter |
Shipping at room temperature
Many people are alarmed when a parcel arrives uncooled. For dry powder that is usually not a problem. These substances are shipped freeze dried precisely because they can go a few days without refrigeration. Trouble comes from long storage, not from a postal delivery.
Prefilled cartridges and pens are a different matter. There the substance is already in solution, and every day out of the fridge counts. Put those away cold straight away.
Every time a sample thaws and refreezes, ice crystals form that damage the chain mechanically. A vial you take out of the freezer ten times is worse off than a vial that spent one day at room temperature. So split a stock into small portions right away.
What you can and cannot see
With a few substances appearance warns you. A copper peptide is blue, and when that colour drains the complex has come apart. Vitamin B12 is bright red and fades in light. A clear solution turning cloudy, or growing flakes, is unusable.
But with most peptides you see nothing. A powder that is half degraded looks exactly like a powder that is intact. That is why storage advice here is not a formality: appearance will not save you.
Practical habits
- Write the date of receipt and the date of dissolving on the vial.
- Keep stock at the back of the freezer, not in the door, where the temperature swings most.
- Take a vial out once and split it into small portions then.
- Store dark. A cardboard box is enough.
- Always let a vial come to temperature before opening it.
This site is made by the team behind Apex Bio Research, a Dutch supplier of research peptides with a certificate of analysis per batch.
Visit the shopThis site explains what the scientific literature says about peptides. It is not medical advice and not a set of instructions. The substances discussed here are research compounds: they are not approved for use in humans or animals. If you have a health question, see a doctor.
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