A certificate of analysis describes the state of a peptide on the day it was tested. Whether the contents of the vial still match it on the day of the experiment depends largely on storage. Peptides are sensitive molecules. Heat, moisture, light or repeated freezing can damage them gradually, often without any visible change.
This guide summarizes how to store peptides according to scientific reviews and the technical guides of laboratory peptide suppliers. General recommendations are not the same as the instructions for a specific product, so we describe the storage of Arion Bios products separately.
Why peptides degrade
A peptide is a short chain of amino acids joined by peptide bonds. These bonds and the side groups of the amino acids can react with water, with oxygen or with each other. The scientific literature distinguishes chemical instability, in which covalent bonds are formed or broken, from physical instability, in which the shape and behavior of the molecules change. The most common degradation pathways are:
- Hydrolysis – water cleaves the peptide bond. The reaction rate depends strongly on pH.
- Oxidation – the sulfur-containing amino acids methionine (Met) and cysteine (Cys) oxidize most easily. Aromatic amino acids such as tryptophan (Trp) are also susceptible. Oxidation is triggered by oxygen, trace metals and light.
- Deamidation – asparagine (Asn) and glutamine (Gln) lose their amide group. In glutamine this happens much more slowly. The rate depends mainly on pH and temperature.
- Aggregation – molecules clump together. It is more common at higher concentrations. Freezing, heating or shaking can also trigger it.
- Adsorption – part of the peptide sticks to the wall of the container. This depends on the packaging material and on the composition of the peptide.
Higher temperatures speed up most of these reactions, which is why peptides are generally stored and transported cold. Other factors are moisture, light and pH. Solutions also carry a risk of microbial contamination. Which pathway dominates is determined mainly by the amino acid composition and sequence. Bachem, for example, notes that peptides containing Asn, Gln, Met, Cys or Trp have a limited shelf life.
Lyophilized powder: the most stable form
Lyophilization is freeze-drying. The peptide is frozen and the water is removed under vacuum. The result is a dry powder or a compact “cake” at the bottom of the vial. Without water, reactions that need it, such as hydrolysis, slow down considerably. This is why proteins are often converted into a solid form in pharmaceutical development to reach an acceptable shelf life. Even in the solid state, however, they are not stable indefinitely.
Laboratory peptide suppliers give similar rules for lyophilized material:
- Long term in the freezer. Sigma-Aldrich recommends −20 °C, and preferably −80 °C for longer storage. Bachem specifies below −15 °C, ideally −50 °C or lower. According to GenScript, most lyophilized peptides remain stable for several years at −20 °C.
- Short term in the refrigerator. Bachem allows a refrigerator at 4 °C for short-term use. Sigma-Aldrich notes that some peptides are stable at 4 °C.
- Dry and tightly closed. Peptides tend to be hygroscopic, meaning they attract moisture from the air. Absorbed water lowers the peptide content of a weighed amount and may reduce stability. Peptides containing Asp, Glu, Lys, Arg or His are particularly prone to this.
- Warm up before opening. A closed vial taken out of cold storage should first be allowed to reach room temperature, ideally in a desiccator. Otherwise moisture from the air condenses on the cold powder.
- Away from bright light. GenScript recommends storing lyophilized peptides protected from bright light.
These values come from guides for custom-synthesized research peptides. They describe general laboratory practice, not the conditions for a specific finished product.
Peptides in solution: a shorter shelf life
This group includes pre-filled pens as well as any peptide dissolved in the lab. In water, hydrolysis, deamidation and aggregation can all take place, so a solution is less stable than a powder. GenScript states that the shelf life of peptides in solution is very limited. Bachem does not recommend long-term storage of solutions. Thermo Fisher adds that the lower the concentration, the less stable the solution.
- Refrigeration at 2–8 °C. According to the general Sigma-Aldrich guide, peptide solutions typically keep for up to about a week at 4 °C. Solutions of peptides containing Asn, Gln, Cys, Met or Trp are less stable.
- Protection from light. Many peptides are light-sensitive. Light-induced oxidation mainly affects aromatic amino acids.
- No repeated freezing and thawing. Each cycle stresses the peptide, and freezing itself can trigger aggregation. In laboratories, a solution intended for longer storage is therefore divided into single-use portions (aliquots) so that each one is thawed only once.
- Sterile handling. Suppliers recommend sterile water or buffers, wearing gloves and, where appropriate, filtering through a 0.2 µm filter to keep bacteria out of the solution.
Arion Bios products: follow the label, do not freeze
The recommendations above come mostly from manufacturers of custom peptides, for whom freezing aliquots is routine laboratory practice. For Arion Bios products, the instructions given with the product and on the packaging apply:
- store at 2–8 °C,
- protect from light,
- do not freeze,
- keep in the original closed packaging.
Why can the instructions for a specific product differ from general rules? The storage conditions on a label are derived from stability studies of that product in its packaging. The European Medicines Agency (EMA) describes the same principle in its storage guideline: for products stable at 5 ± 3 °C it uses the statement “store in a refrigerator (2–8 °C)”, with “do not freeze” added where relevant. Low temperatures can cause physical changes in some forms or affect the packaging.
The rule is therefore simple: the label and instructions of the specific product always take precedence over general recommendations, including those in this article. Do not put Arion Bios pre-filled pens or vials in the freezer, even though general laboratory guides do work with freezing. When the conditions are met, the product is stable for the period stated on the packaging. You can find the certificate of analysis for your batch on our certificates of analysis page, using the production date printed on the packaging.
The cold chain during shipping
The cold chain means that a product stays within its prescribed temperature range all the way: in the warehouse, in transit and after delivery. In its guidance on the storage and transport of temperature-sensitive products, the World Health Organization (WHO) defines the storage temperature as the range stated on the label. A temperature excursion occurs when a product is exposed to temperatures outside this range. What excursion is still acceptable is determined by the manufacturer on the basis of stability data.
A short excursion matters differently for a lyophilized powder and for a solution. Sigma-Aldrich states that lyophilized peptides are shipped at ambient temperature and remain stable for days to weeks. Thermo Fisher, by contrast, ships its peptide solutions on ice and asks for them to be frozen immediately on receipt. A solution is simply more sensitive to temperature. Even a powder, however, belongs in the conditions set by its label once it has arrived.
How we handle it: we keep products refrigerated, dispatch orders within 24 hours on business days and pack them in thermo-insulated packaging with cooling packs. Delivery times by country are listed on the Shipping & payment page, and more practical information is in our product guide. After delivery, we recommend the following:
- Collect the parcel as soon as possible, especially if it is waiting at a pickup point.
- Unpack it straight away and place the products in the refrigerator (2–8 °C).
- Leave them in the original closed packaging and do not put them in the freezer or the freezer compartment.
- If you have any doubts about the condition of the shipment, contact us and quote the production date from the packaging.
Light, packaging and signs of a possible problem
Light can trigger oxidation, especially in peptides containing aromatic amino acids. For light-sensitive products, the EMA guideline introduces a statement on keeping them in the original package or in the outer carton. The box is therefore more than shipping packaging. It protects the contents from light, so keep pens and vials in it until they are used in the lab.
During a routine visual check, the following changes deserve attention:
- Solution: cloudiness, flakes, visible particles or a change in color. These may be linked to aggregation, precipitation or a chemical change.
- Lyophilized powder: a shrunken or collapsed cake, a sticky or liquefied mass, droplets on the vial wall. Cake appearance alone does not decide quality, however. Some variations arise during manufacturing and do not affect quality. A powder that has become damp is a reason for caution, because moisture reduces stability.
Many chemical changes, such as deamidation or oxidation, are not visible to the eye. Only an analytical method such as HPLC will reveal them. If you are unsure about the condition of the material, do not use it for an experiment and contact the supplier.
Quick reference
Typical peptide storage temperatures and handling recommendations from laboratory peptide suppliers. The numbers refer to the list of sources at the end of the article.
| Form | Situation | Typical general recommendation | Source |
|---|---|---|---|
| Lyophilized powder | Long-term storage | Freezer, −20 °C or lower (−80 °C or below −15 °C are also cited) | 3, 5, 6 |
| Lyophilized powder | Short-term storage | Refrigerator, about 4 °C | 3, 5 |
| Lyophilized powder | Shipping | Usually tolerates ambient temperature for days to weeks | 4 |
| Lyophilized powder | Opening | Let the closed vial reach room temperature first | 3, 5, 6, 7 |
| Solution | Short-term storage | Refrigerator, on the order of days, generally up to about a week | 3, 7 |
| Solution | Longer storage in the lab | Single-use aliquots, no repeated freezing and thawing | 3, 5, 6, 7 |
| Solution | Handling | Protect from light, work under sterile conditions | 6, 7 |
| Arion Bios products (pens and vials) | Always | 2–8 °C, protect from light, do not freeze, keep in the original closed packaging. Follow the label. | Product instructions |
Frequently Asked Questions
How long does a peptide last in the fridge?
It depends on the specific peptide, its form and its packaging. For Arion Bios products, the shelf life stated on the packaging applies, provided the product is stored at 2–8 °C according to the label. The general literature on laboratory peptides states that lyophilized material can be kept in a refrigerator short term (Bachem) and that ordinary peptide solutions typically keep for up to about a week at 4 °C (Sigma-Aldrich). These rough figures do not apply to finished products with their own stability data.
Can I freeze a peptide to make it last longer?
In laboratories, lyophilized custom peptides and solution aliquots are routinely stored frozen. Do not freeze Arion Bios products, however. Their instructions specify 2–8 °C, and the label takes precedence over general recommendations.
Is it a problem if the parcel was out of the fridge for a few hours?
We ship in thermo-insulated packaging with cooling packs, which protects the contents from temperature swings in transit. According to the WHO, the manufacturer decides whether an excursion is acceptable based on stability data. Lyophilized powder is generally less sensitive to short excursions than a solution. What matters is putting the parcel in the refrigerator immediately after receipt. If it was out of the cold for much longer, please contact us.
Can I tell from its appearance that a peptide is damaged?
Only partly. Cloudiness, particles or a change in color of a solution are warning signs. Many chemical changes, however, are invisible and only show up in an analysis. Conversely, not every variation in the appearance of a lyophilized cake means lower quality.
Summary
Heat, moisture and light speed up peptide degradation. Lyophilized powder is generally more stable than a solution and copes better with a short temperature excursion. Solutions, including pre-filled pens, need constant refrigeration and protection from light. For Arion Bios products, however, the label always decides: 2–8 °C, protect from light, do not freeze, original closed packaging.
Sources
- Nugrahadi PP, Hinrichs WLJ, Frijlink HW, Schöneich C, Avanti C. “Designing Formulation Strategies for Enhanced Stability of Therapeutic Peptides in Aqueous Solutions: A Review.” Pharmaceutics, 2023;15(3):935. DOI: 10.3390/pharmaceutics15030935
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. “Stability of Protein Pharmaceuticals: An Update.” Pharmaceutical Research, 2010;27(4):544–575. DOI: 10.1007/s11095-009-0045-6
- Sigma-Aldrich (Merck). “Handling and Storage Guidelines for Peptides and Proteins.” Technical article: sigmaaldrich.com
- Sigma-Aldrich (Merck). “Synthetic Peptide Handling & Storage Protocol.” Laboratory protocol: sigmaaldrich.com
- Bachem. “Handling and Storage Guidelines for Peptides.” Knowledge Center: bachem.com
- GenScript. “Peptide Storage and Handling Guidelines.” genscript.com
- Thermo Fisher Scientific. “Important Information on your HeavyPeptides” (handling and storage instructions for AQUA peptides): thermofisher.com
- Wang W. “Lyophilization and development of solid protein pharmaceuticals.” International Journal of Pharmaceutics, 2000;203(1–2):1–60. DOI: 10.1016/S0378-5173(00)00423-3
- World Health Organization (WHO). “Model guidance for the storage and transport of time- and temperature-sensitive pharmaceutical products.” WHO Technical Report Series No. 961, Annex 9, 2011: who.int
- European Medicines Agency (EMA). “Guideline on Declaration of Storage Conditions.” CPMP/QWP/609/96/Rev 2, 2007: ema.europa.eu
- Patel SM, Nail SL, Pikal MJ, Geidobler R, Winter G, Hawe A, Davagnino J, Rambhatla Gupta S. “Lyophilized Drug Product Cake Appearance: What Is Acceptable?” Journal of Pharmaceutical Sciences, 2017;106(7):1706–1721. DOI: 10.1016/j.xphs.2017.03.014