Key facts
- For long-term storage, manufacturers recommend lyophilised peptides at -20 °C or colder, away from bright light; GenScript says most are stable for several years this way.[3][4]
- For short-term use, lyophilised peptides may be kept in a refrigerator at 4 °C, and they are stable at room temperature for days to weeks.[2][5]
- Peptide solutions are, in general, stable for up to a week at 4 °C; frozen solutions may be kept for a few weeks.[4][2]
- Peptides containing Cys, Met, Trp, Asn or Gln have limited shelf lives, especially in solution.[1][4]
- Always let a cold vial warm to room temperature before opening, so moisture from the air does not condense on the powder.[1][3]
How to Store Peptides
Store peptides as lyophilised powder in a tightly closed vial at -20 °C or colder for the long term, away from bright light, and keep them dry; GenScript says most lyophilised peptides are stable for several years under these conditions.[3][2]
| Form | Temperature | How long | Notes |
|---|---|---|---|
| Lyophilised, long-term | -20 °C or colder (-80 °C or -50 °C or lower preferred by some manufacturers) | Several years for most peptides[3] | Tightly capped, dry, away from bright light[4][2] |
| Lyophilised, short-term | 4 °C (refrigerator) | Short-term use[2] | Sigma-Aldrich advises 4 °C or colder on receipt[5] |
| Lyophilised, room temperature | Ambient | Days to weeks[5] | Suitable for shipping[2] |
| Solution, refrigerated | 4 °C | Up to a week, in general[4] | Freeze instead if the sequence is unstable or pH is above 8[4] |
| Solution, frozen aliquots | -15 °C to -20 °C or colder | A few weeks[2] | pH 5 to 6 buffer, single-use aliquots, no freeze-thaw[3][4] |
Manufacturers agree that stability is unique to each peptide and depends on its sequence, so these figures are general guidance rather than a guaranteed shelf life.[3] Where a product label states its own storage conditions, follow the label.[2]
Storing Lyophilized Peptides
Lyophilised peptides keep best at -20 °C or colder for long-term storage, while a refrigerator at 4 °C is acceptable for short-term use.[3][2]
- Temperature. Bachem advises below -15 °C for maximum stability, with lower temperatures preferred, for example -50 °C or lower for long-term storage.[1][2] Sigma-Aldrich recommends -20 °C or preferably -80 °C as the most effective way to minimise degradation.[4]
- Short-term. Peptides with limited shelf lives may still be stored in a refrigerator at 4 °C for short-term use.[2] Sigma-Aldrich advises storing lyophilised peptide at 4 °C or colder on receipt.[5]
- Moisture. Peptides are often hygroscopic, and absorbed water reduces the peptide content and may decrease stability.[1] Peptides containing Asp, Glu, Lys, Arg or His are prone to absorbing moisture from the air and should be kept in a desiccator in a tightly capped vial.[3]
- Light. Store away from bright light.[3][4]
- Air. Sequences containing Cys, Met or Trp are prone to air oxidation; Sigma-Aldrich recommends purging the vial with nitrogen or argon.[4]
Let the vial warm before opening. Take the vial out of cold storage and let it reach room temperature, ideally in a desiccator, before removing the cap. This stops moisture from the surrounding air condensing on the cold powder.[1][4] Then weigh out what you need quickly, reseal the vial tightly and return the rest to cold, dry storage.[3] GenScript also advises against opening the stock vial repeatedly.[3]
Storing Reconstituted Peptides
Peptides in solution have a much shorter shelf life than lyophilised powder: Sigma-Aldrich gives up to a week at 4 °C in general, and Bachem says frozen solutions may be kept for a few weeks.[4][2]
- Avoid storing in solution where you can. Bachem advises against storing peptides in solution, even sterile and oxygen-free, because they may slowly degrade chemically. GenScript also does not recommend it, partly because solutions are susceptible to bacterial degradation.[2][3]
- Aliquot. If you must store a solution, divide it into single-use aliquots and freeze them below -15 °C (Bachem) or at -20 °C (GenScript).[1][3]
- Avoid freeze-thaw. Repeated freeze-thaw cycles degrade both lyophilised peptides and peptide solutions, so take one aliquot at a time.[4][3]
- Buffer and pH. Sterile buffers at pH 5 to 6 prolong storage life, exposure to pH above 8 should be avoided, and solutions at pH above 8 should be frozen when not in use.[4][3]
- Sterility. A 0.2 µm filter can remove potential bacterial contamination. If you dissolved too much, re-lyophilising the excess helps keep it stable.[3]
Why it varies by sequence. Bachem and Sigma-Aldrich both name Asn, Gln, Cys, Met and Trp as residues that limit shelf life in solution; GenScript adds Asp and N-terminal Glu.[2][4][3] Cys, Met and Trp oxidise in air: all cysteine-containing peptides slowly oxidise over time, and free Cys thiols are rapidly oxidised to disulfides above pH 7.[4][2] Methionine can be oxidised to methionine sulfoxide in the presence of oxygen and trace metal ions.[7] Asn deamidates, by direct hydrolysis in acid or through a cyclic imide intermediate at neutral to alkaline pH, and at neutral to alkaline pH the rate depends on the neighbouring residue on its C-terminal side.[6]
To work out the concentration of a reconstituted vial, use the peptide reconstitution calculator.
How Long Do Peptides Last After Reconstitution?
In general, reconstituted peptides are stable for up to a week at 4 °C, and frozen aliquots may be kept for a few weeks, but the exact figure depends on the sequence and no single number applies to every peptide.[4][2][3]
- In the fridge (4 °C): up to a week, in general. If the sequence is inherently unstable, Sigma-Aldrich suggests freezing the solution when not in use.[4]
- Frozen: a few weeks for frozen solutions; long-term storage of solutions is not recommended.[2]
- Shorter for some sequences: peptides containing Asn, Gln, Cys, Met or Trp are unstable in solution.[4][1]
Does Temperature During Shipping Matter?
Lyophilised peptides are stable at room temperature for days to weeks, which is why manufacturers such as Bachem ship them at ambient temperature.[5][2]
Bachem notes that even peptides with limited shelf lives may be shipped at room temperature, and that most of its orders arrive within 1 to 2 working days, with the long-term storage conditions printed on the label.[2] Once a vial arrives, move it to the storage temperature on the label. Room-temperature stability covers the powder only; it does not apply to peptide solutions.[5][4]
Storing Eloralintide Vials
Store sealed eloralintide vials refrigerated at 2 to 8 °C and away from light, which is the storage condition we state for every vial we sell.
- Our eloralintide is supplied as sealed lyophilised powder in 5, 10 and 20 mg vials. See the vials.
- Keep the vial sealed until it is needed and protect it from light, in line with manufacturer guidance to store lyophilised peptides away from bright light.[3]
- Before opening a refrigerated vial, let it reach room temperature so moisture does not condense on the powder.[1]
- For long-term holding beyond short-term use, general manufacturer guidance for lyophilised peptides is -20 °C or colder.[3][2]
Frequently Asked Questions
How long do peptides last in the fridge?
Lyophilised peptides may be kept in a refrigerator at 4 °C for short-term use. Peptide solutions are, in general, stable for up to a week at 4 °C, and less for unstable sequences. For longer storage, manufacturers recommend -20 °C or colder.
How long are peptides good for after reconstitution?
It varies by sequence. Sigma-Aldrich gives up to a week at 4 °C in general, and Bachem says frozen solutions may be kept for a few weeks. Peptides containing Asn, Gln, Cys, Met or Trp are less stable in solution.
Can lyophilized peptides be stored at room temperature?
For a short time. Sigma-Aldrich says lyophilised peptides are stable at room temperature for days to weeks, which is why they can ship at ambient temperature. For longer storage, keep them at -20 °C or colder.
Should peptides be frozen?
For long-term storage, yes: lyophilised peptides keep best at -20 °C or colder. Solutions that must be kept should be frozen as single-use aliquots, because repeated freeze-thaw cycles degrade peptides.
Do peptides need to be kept in the dark?
Manufacturers including GenScript and Sigma-Aldrich advise storing peptides away from bright light. Our sealed eloralintide vials should be kept at 2 to 8 °C and away from light.
Why should a peptide vial warm up before opening?
Peptides are often hygroscopic. Opening a cold vial lets moisture from the air condense on the powder, which reduces peptide content and may lower stability. Let it reach room temperature first, ideally in a desiccator.
Sources
- Bachem, Care and Handling of Peptides (Knowledge Hub)
- Bachem Peptide Guide, Handling and Storage Guidelines for Peptides
- GenScript, Peptide Storage and Handling Guidelines
- Sigma-Aldrich (Merck), Handling and Storage Guidelines for Peptides and Proteins
- Sigma-Aldrich, Storage and Handling of Synthetic Peptides (PDF guide)
- Patel K, Borchardt RT. Chemical pathways of peptide degradation. III. Deamidation of asparaginyl residues in hexapeptides. Pharm Res 1990;7(8):787-793. PMID 2235875
- Li S, Schöneich C, Borchardt RT. Chemical pathways of peptide degradation. VIII. Oxidation of methionine in small model peptides. Pharm Res 1995;12(3):348-355. PMID 7617519
For research use only. Not for human or veterinary consumption. This guide summarises published research for information only. It is not medical advice and does not describe any use of products sold on this site.