Do research peptides need to be shipped cold?

Lyophilised peptides do not. The dry cake is stable at ambient temperature for far longer than a courier transit takes, because the water that drives hydrolysis and deamidation has been removed. Material in solution is a different case entirely, which is why peptides are supplied dry.

How long can a vial sit at room temperature?

An unopened lyophilised vial tolerates weeks at ambient without meaningful loss, which is the margin that makes ambient shipping reasonable. That is not a reason to store it there — the degradation is slow rather than absent, and at -20°C it is slower still by a wide margin.

Is -20°C enough, or does it need -80°C?

-20°C is the storage condition on the certificate and is appropriate for lyophilised material over the shelf life stated for it. -80°C extends that further and is standard practice in laboratories that already have the equipment, but the difference matters over years, not months.

Can I use a domestic freezer?

It will hold the temperature, but check whether it is frost-free. Auto-defrost cycles warm the compartment above freezing at intervals, so the vial is not actually being held at the certificate's storage condition. A manual-defrost unit is the better choice for anything kept longer than a few weeks.

The cake has shrunk or collapsed. Is the vial ruined?

Not necessarily. Cake appearance depends on the lyophilisation cycle and on how the vial has been handled, and a collapsed cake can still assay to specification. It does indicate the vial has been warm or damp at some point, so it is worth documenting before use and worth raising with us if it arrived that way.

Research guides

How to store research peptides

Lyophilised peptides at -20°C, reconstituted at 2–8°C, ambient in transit. Why the dry cake tolerates shipping, and what actually degrades a vial.

A peptide vial spends its life in three states, and each one has different rules. It travels as a dry cake at whatever temperature the courier network happens to be. It waits in a freezer as that same dry cake. Then it is dissolved, and from that moment it is on a much shorter clock. Most storage mistakes come from applying the rules for one state to another.

Why lyophilised peptides ship at ambient temperature

Lyophilisation — freeze-drying — removes almost all the water from a peptide solution under vacuum, leaving the white cake or powder at the bottom of the vial. That matters because water is the reagent in most of the reactions that degrade a peptide. Hydrolysis needs it. Deamidation of asparagine and glutamine residues, the slow chemical drift that turns a peptide into something with the same mass but different behaviour, proceeds through it. Take the water away and the reactions that need it effectively stop.

The practical consequence is that a dry peptide is a fundamentally different material from a dissolved one. In solution, ambient temperature is a problem measured in hours or days. As a lyophilised cake, ambient temperature is tolerated for the length of a courier transit without meaningful loss — which is why peptides are shipped dry and at ambient, by every supplier, rather than packed in dry ice. A cold chain protects material that would otherwise degrade in transit. Lyophilised peptide is not that material.

This is a property of the material, not a shortcut. Our stock is held in a freezer here and ships at ambient because the dry cake tolerates the journey; that is the same reason your vial goes into a freezer on arrival rather than staying on a shelf. Transit is short. Storage is not.

What to do when the vial arrives

Three things, in this order, and the first one is the one most often skipped.

Let the vial reach room temperature before you open it, if it arrived cold from a winter delivery. Opening a cold vial in a warm room pulls humid air onto a cold surface and condenses water directly into the cake. That is the one avoidable way to wet a peptide you have not even used yet.
Check the cake against the certificate. It should be a white to off-white solid. A cake that has collapsed into a film or slid down the vial wall has been warm and damp at some point in its life; it is not necessarily degraded, but it is worth photographing before you go further.
Put unreconstituted vials at -20°C, protected from light. That is the storage condition on the certificate and on every product page, and it is where a vial should live until the day it is dissolved.

Light, moisture, and the freezer you use

Amber glass and an opaque box both work; what you are protecting against is photo-oxidation of the aromatic residues — tryptophan, tyrosine, phenylalanine — which is slow but cumulative, and entirely avoidable by keeping the vial dark. A cardboard box in the freezer is sufficient. It does not need to be elaborate.

Moisture is the harder one, because a lyophilised cake is hygroscopic: it will pull water out of the air given the chance. The vial is sealed under vacuum or inert gas and stoppered, so an unopened vial is not at risk. The risk begins the first time the stopper is pierced, and it is the reason a vial that has been opened should not be treated as though it is still sealed.

One thing worth checking about your freezer: most domestic and many laboratory freezers are frost-free, which means they periodically warm the compartment above freezing to clear ice, then cool it again. For food that is invisible and harmless. For a vial it means the contents are not actually being held at -20°C — they spend part of every cycle warmer than the storage condition on the certificate. A manual-defrost freezer, or a laboratory unit that holds -20°C steadily, is the better place for anything you intend to keep for months.

After reconstitution

Once bacteriostatic water goes in, the clock changes. Reconstituted material is kept at 2–8°C — an ordinary refrigerator, not the freezer — and used within the window appropriate to the compound. That is the storage condition on the certificate and on every product page, and it is the one the stated window assumes.

The shelf-life article covers what that window depends on and why it varies so much between compounds.

Storage at a glance

State	Temperature	Notes
In transit, lyophilised	Ambient	Tolerated for the length of a courier journey
Stored, unreconstituted	-20°C	Dark, sealed, manual-defrost freezer preferred
Stored, reconstituted	2–8°C	Refrigerated, not frozen; use within the compound's window
Long-term, unreconstituted	-20°C or below	Same conditions; the dry cake is what tolerates long storage

Shipping and storage in Finland and the Nordics

Two things are specific to this part of Europe, and neither changes the guidance above. The first is that intra-Nordic and intra-EU transit is short, so the ambient portion of a vial's life is measured in days. The second is that a Finnish winter delivery can arrive genuinely cold and a Finnish summer delivery genuinely warm, and the lyophilised cake tolerates both — but the condensation problem described above is real in a Finnish January, when the temperature difference between a doorstep and a heated room is substantial. Let the vial equilibrate before opening it.

Storage requirements are the same everywhere: a freezer that holds -20°C without cycling, and darkness. Nothing about the destination changes what the material needs.

Common questions

Do research peptides need to be shipped cold?: Lyophilised peptides do not. The dry cake is stable at ambient temperature for far longer than a courier transit takes, because the water that drives hydrolysis and deamidation has been removed. Material in solution is a different case entirely, which is why peptides are supplied dry.
How long can a vial sit at room temperature?: An unopened lyophilised vial tolerates weeks at ambient without meaningful loss, which is the margin that makes ambient shipping reasonable. That is not a reason to store it there — the degradation is slow rather than absent, and at -20°C it is slower still by a wide margin.
Is -20°C enough, or does it need -80°C?: -20°C is the storage condition on the certificate and is appropriate for lyophilised material over the shelf life stated for it. -80°C extends that further and is standard practice in laboratories that already have the equipment, but the difference matters over years, not months.
Can I use a domestic freezer?: It will hold the temperature, but check whether it is frost-free. Auto-defrost cycles warm the compartment above freezing at intervals, so the vial is not actually being held at the certificate's storage condition. A manual-defrost unit is the better choice for anything kept longer than a few weeks.
The cake has shrunk or collapsed. Is the vial ruined?: Not necessarily. Cake appearance depends on the lyophilisation cycle and on how the vial has been handled, and a collapsed cake can still assay to specification. It does indicate the vial has been warm or damp at some point, so it is worth documenting before use and worth raising with us if it arrived that way.

Peptide shelf life and stability
How long lyophilised and reconstituted peptides keep, and the four things that shorten it: temperature, moisture, light and oxidation. Storage figures included.
How to reconstitute lyophilised peptides
How to reconstitute a lyophilised peptide with bacteriostatic water without damaging it: why you run the liquid down the vial wall and never shake it.
Bacteriostatic water vs sterile water
Bacteriostatic water is sterile water plus 0.9% benzyl alcohol, which is what makes a vial multi-use. When each one is the right choice, and why it matters.

About this article

Everything reported here comes from published research, and each finding names the model the study used — cell culture, rat, or human. Findings in one model do not transfer to another, most of the work described is preclinical, and none of it is a claim that a compound is safe or effective for any purpose. Nothing on this page describes doses, routes of administration, or use in a person.

Approval status varies by compound and by country. A few of the substances described are the active ingredient of medicines authorised in the EU; most have no marketing authorisation anywhere and have never been assessed by a regulator. Neither is supplied as a medicine here. All material supplied by ASSAY is sold for in-vitro laboratory research only, and is not a drug, food, cosmetic or medical device, and not for human or veterinary use.

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