Frequently asked questions

Research laboratories, institutions and their purchasers aged 21 or older. Every order requires confirmation that the products are for laboratory research use only, not for human or veterinary use.

Yes — every lot is HPLC-tested for purity and LAL-tested for endotoxins by USA Prime Labs, our affiliated laboratory. The measured purity is on each lot's certificate. COAs are on each product page and in the COA library.

The item isn't on our shelf and will be synthesized by our partner lab. Everything ships within a week — made-to-order items ship directly after synthesis, and tracking is emailed as soon as the order is on the way.

The contiguous United States only — the lower 48 states and Washington, DC. We don't ship to Alaska, Hawaii, U.S. territories (such as Puerto Rico or Guam), APO/FPO military addresses, or internationally.

You choose at checkout: USPS Ground Advantage (standard, typically 2–5 business days), Priority Mail (ground price + $10, typically 1–3 business days) or Priority Mail Express ($59.99, typically 1–2 business days, overnight to most addresses). Delivery times count from when your order ships. Orders over $200 ship free by Ground Advantage — you can still upgrade. Temperature-sensitive items ship fast with cold packs.

The payment methods currently available are shown at checkout. Card details are handled by our payment processor and never touch our servers.

Every product page links the current lot's certificates (purity, metals, endotoxin), and the full archive is in the COA library. Match the lot number printed on your vial's label; if you can't find it, contact us with the lot number and we'll send it directly.

Yes — qualifying sizes carry automatic volume discounts at 5+ and 10+ units, shown on the product page. For standing wholesale or institutional supply, contact us and we'll set up an account.

Peptides are short chains of amino acids joined by peptide bonds. Chains of roughly 2 to 50 amino acids are usually called peptides; longer chains that fold into a stable 3D structure are called proteins. Many hormones and signaling molecules in living organisms are peptides.

Most research peptides are made by solid-phase peptide synthesis: amino acids are added one at a time to a growing chain anchored on resin beads, using protecting-group chemistry such as Fmoc. The finished chain is cleaved from the resin, purified by preparative HPLC and freeze-dried into a powder. Longer proteins, such as growth hormone, are made recombinantly by expressing the gene in cells and purifying the protein.

Peptides supplied as laboratory reagents for in vitro and other non-clinical research. They are not approved drugs, are not manufactured or labeled as medicines, and are sold for laboratory research use only, not for human or veterinary use.

Many peptides can be lawfully purchased in the United States as research chemicals for laboratory use. They are not approved drugs, and it is unlawful to sell them for human consumption or market them with health claims. Some peptides are also active ingredients of FDA-approved prescription medicines, and sports bodies such as WADA prohibit many of them. This is general information, not legal advice.

"Research use only" (RUO) means the product is supplied solely for laboratory research. It is not intended for diagnostic or therapeutic use, has not been approved as a drug, and must not be used in humans or animals. Every product we sell is labeled: For laboratory research use only. Not for human or veterinary use.

A peptide that was dissolved, frozen, and then dried under vacuum so the ice turns straight to vapor (sublimation). The result is a stable dry powder or small "cake" that can look like a white puck, loose powder or a thin film on the vial wall; all are normal. Lyophilized peptides keep far longer than peptides in solution.

It is the amount of peptide in the vial, for example 10 mg. It is not a concentration: the concentration depends on the volume of diluent added when the powder is reconstituted (mg ÷ mL). For blends, the label states the amount of each component.

Synthetic peptides are built one amino acid at a time by solid-phase chemical synthesis, which works well up to about 50 residues. Longer chains that must fold into a specific 3D structure, such as 191-amino-acid growth hormone, are made recombinantly: the gene is expressed in cells (commonly E. coli or yeast) and the protein is purified from them.

A vial containing two or more peptides that were combined in solution in a set ratio and then freeze-dried together. The label states the mass of each component. Testing a blend is more involved than testing a single peptide: HPLC has to resolve each component as its own peak, and mass spectrometry should confirm each expected molecular weight.

Peptides are made of amino acids linked end to end by peptide (amide) bonds, each joining the carboxyl group of one amino acid to the amino group of the next. Natural peptides use the 20 standard amino acids. Synthetic research peptides can also contain non-standard building blocks, such as D-amino acids or Aib, and modifications such as an acetylated N-terminus, a C-terminal amide, a fatty-acid chain or a bound metal ion, as in GHK-Cu. A lyophilized powder also contains counter-ions, such as acetate or trifluoroacetate, and some residual water.

In cells, peptides are made by ribosomes, which translate messenger RNA into a chain of amino acids. Many peptide hormones and signaling peptides start as a longer precursor protein that enzymes, such as prohormone convertases, cut into the active fragment, which is often modified further, for example by C-terminal amidation. A few small peptides, such as glutathione, are instead assembled by dedicated enzymes without a ribosome.

Most are made by solid-phase peptide synthesis (SPPS). The first amino acid is anchored to a resin bead; its protecting group (commonly Fmoc) is removed; the next protected amino acid is activated and coupled; excess reagents are washed away; and the cycle repeats until the sequence is complete. The chain is then cleaved from the resin, usually with trifluoroacetic acid, which also strips the side-chain protecting groups. Finally the crude peptide is purified by preparative HPLC, freeze-dried, and tested for identity and purity.

A synthetic peptide with the same sequence as a natural peptide is the same molecule; only the source differs. Natural peptides are made by living organisms in small amounts alongside many other molecules, so research material is almost always produced by chemical synthesis or recombinant expression. Synthetic peptides can also be designed with features not found in nature, such as D-amino acids, non-standard residues or attached fatty acids, to change their stability or receptor binding. Many research peptides are such analogues rather than exact copies of natural sequences.

Peptides carry much of the chemical signaling in living organisms: many hormones, such as insulin, glucagon and oxytocin, as well as neuropeptides and antimicrobial peptides, are peptides. In research they are valued as tools because they can bind a specific receptor or enzyme selectively, can be synthesized to an exact sequence, and can be changed one residue at a time to study structure and function. Peptides are also the active ingredients of a growing number of approved medicines.

Not as a category. The FDA approves specific drug products, and dozens of FDA-approved medicines have a peptide as the active ingredient, including insulin and the GLP-1 receptor agonists. Most compounds sold as research peptides are not approved for any use, and when a compound is an approved active ingredient, the approval covers the finished medicine made under pharmaceutical controls, not reagent-grade material. Everything sold here is for laboratory research use only, not for human or veterinary use.

No. GLP-1 (glucagon-like peptide-1) is one specific peptide hormone, 30 or 31 amino acids long depending on the form, made in the intestine from the proglucagon precursor. Some research peptides, such as semaglutide, tirzepatide and retatrutide, are synthetic analogues that act on the GLP-1 receptor, alone or together with other receptors. Most peptides, such as BPC-157, GHK-Cu or ipamorelin, have nothing to do with the GLP-1 receptor.

A peptide blend holds two or more peptides co-lyophilized in a fixed ratio in one vial; an individual peptide vial holds a single compound. Blends save reconstitution steps and keep the ratio identical from vial to vial. Single vials let a researcher vary each compound independently, run single-compound controls and track each compound with its own Certificate of Analysis. For a blend, check that the COA resolves every component as its own HPLC peak and confirms each expected molecular weight.

Because peptides are far more stable dry. In water, peptide bonds slowly hydrolyze and residues such as asparagine, glutamine and methionine deamidate or oxidize; removing the water by lyophilization (freeze-drying) slows these reactions dramatically, so the powder keeps for months to years when cold. A dry powder also tolerates a few days at ambient temperature in transit and lets the researcher choose the diluent and concentration at reconstitution.

A propeptide is a segment of a precursor protein that is cut away to produce the mature, active peptide or protein. For example, proinsulin becomes insulin when its connecting C-peptide is removed, and many hormones are made as prohormones that enzymes trim into their active form. Some propeptides also help the protein fold correctly before they are removed.

California regulates drugs under its own Sherman Food, Drug, and Cosmetic Law, which largely mirrors the federal framework. As under federal law, a peptide may not be sold for human consumption or marketed with health claims unless it is an approved drug supplied lawfully, while peptides sold as research chemicals for laboratory use are a separate category. Rules can change, so check current requirements for your institution. This is general information, not legal advice.

In the European Union, medicinal products must be authorized by the European Medicines Agency or a national regulator before they can be sold for human use, and most research peptides are not authorized. The sale of peptides as research chemicals is governed mainly by national law, which differs from country to country, and some countries classify certain peptides as prescription-only medicines or restrict their import. Check the rules of the specific country. This is general information, not legal advice.

Many are prohibited. The World Anti-Doping Agency (WADA) Prohibited List bans peptide hormones, growth factors, related substances and mimetics (class S2) at all times, and its class S0 covers any pharmacological substance not approved for human therapeutic use, which includes most research peptides. The NCAA keeps its own banned-drug list with a similar peptide-hormone class. The current list of the relevant governing body is the authority. This is general information, not legal advice.

You cannot tell by looking. Ask for a Certificate of Analysis that carries the same lot number as your vial, shows an HPLC purity result with its chromatogram, and confirms identity by mass spectrometry (observed molecular weight against the expected value). Endotoxin results add assurance. If in doubt, send a sealed vial to an independent laboratory for testing.

Mainly by reverse-phase high-performance liquid chromatography (HPLC), which separates the target peptide from impurities such as truncated or deleted sequences and reports purity as a percentage of peak area. Mass spectrometry confirms identity. Endotoxin (LAL) testing, heavy-metals testing and peptide-content analysis complete the picture.

It is the share of the material detected by the HPLC instrument (usually by UV absorbance at about 214–220 nm) that belongs to the target peptide's peak. A result of 98% means the other peaks, mostly related peptide impurities, make up 2% of the detected area. HPLC purity does not measure water, salts or counter-ions, so it is not the same as the net amount of peptide in the vial.

A document issued by the testing laboratory for one specific lot. It names the compound and lot number, lists the tests performed and their methods, and reports the results, such as HPLC purity, mass-spectrometry identity and endotoxin level, with the test date and the laboratory's details. Every lot we sell has one, linked on the product page and archived in the COA library.

Check, in order: the lot number matches the label on your vial; the compound name and expected molecular weight are correct; the mass-spectrometry result is close to that expected weight; the HPLC purity meets the stated grade and the chromatogram shows one dominant peak; the endotoxin result is reported in EU/mg where applicable; and the test date and laboratory are identified.

Identity. Mass spectrometry measures the molecular weight of the material, so a result matching the peptide's theoretical mass confirms that the right molecule is present. HPLC alone cannot do this, because a wrong or mislabeled peptide could still produce a single clean peak.

Endotoxins are lipopolysaccharides from the cell walls of gram-negative bacteria. They survive heat and pass through sterilizing filters, and even small amounts can trigger strong responses in cell-culture and other biological assays, confounding results. The Limulus amebocyte lysate (LAL) test measures them, reported in endotoxin units per milligram (EU/mg).

Testing performed by a laboratory that is independent of the manufacturer and the seller. Our lots are tested by USA Prime Labs, our affiliated laboratory, which is related to us and so is not independent; every result is published on a per-lot Certificate of Analysis. You are welcome to send any sealed vial to an independent laboratory of your choice for confirmation.

For most synthetic research peptides, 95% or higher by HPLC is the common minimum and 98% or higher is typical of high-grade material. Recombinant proteins are graded differently, for example our HGH 191AA is a 97% grade. The right threshold depends on the experiment: sensitive assays call for the highest purity available.

Look for per-lot Certificates of Analysis whose lot numbers match the vials, with both HPLC purity and mass-spectrometry identity; endotoxin results; clear research-use-only labeling with no health claims; a real business address and responsive support; and consistent results when lots are tested independently.

The chemistry is the same wherever a peptide is made, and much of the world's peptide synthesis, including material sold by many U.S. vendors, takes place outside the United States. What matters is how each lot is verified: an identity-confirmed, purity-tested Certificate of Analysis tied to the lot in your hands. USA Prime Peptides ships from the United States and documents every lot.

Check that the COA carries the same lot number as your vial and names the testing laboratory, with its address and a test date. Look for the underlying data, such as the HPLC chromatogram and mass spectrum, not just a purity figure. If the report has a verification code or link, confirm it on the laboratory's own website, or contact the laboratory directly. Warning signs include identical chromatograms across different lots, a missing lot number and purity figures with no method. Our COAs are issued per lot by USA Prime Labs, our affiliated laboratory.

The nominal concentration is calculated: the peptide mass on the label divided by the volume of diluent added (mg ÷ mL), so 10 mg in 2 mL gives 5 mg/mL. To measure it, laboratories use UV absorbance at 280 nm for peptides containing tryptophan or tyrosine (with the sequence's extinction coefficient), absorbance near 205–214 nm for others, quantitative HPLC against a reference standard, or amino-acid analysis. Because powders contain water and counter-ions, the measured peptide content is usually somewhat lower than the gross weight.

Purity describes what the material is: the share of the detected material that is the target peptide, usually by HPLC peak area. Concentration describes how much is dissolved in a given volume, in mg/mL. A 99%-pure peptide can be at any concentration, depending on how much diluent is added, and a solution's concentration says nothing about its impurities. A third figure, net peptide content, is the share of the powder's weight that is peptide rather than water and counter-ions.

Most peptide impurities are related peptides formed during synthesis: deletion sequences missing an amino acid, truncated chains, chains with a protecting group left on, and versions in which an amino acid's configuration has flipped (racemization). Others form later, such as oxidized methionine, deamidated asparagine or aggregates. Powders also contain non-peptide material, mainly water and counter-ions such as trifluoroacetate or acetate. HPLC separates the related impurities, and mass spectrometry helps identify them by molecular weight.

Keep lyophilized peptides cold, dry and dark: refrigerated at 2–8 °C for short-term storage, or frozen at −20 °C or below for long-term storage. Let a cold vial reach room temperature before opening it so moisture does not condense on the powder. Keep reconstituted peptides refrigerated and avoid repeated freeze-thaw cycles.

For storage, yes. Lyophilized peptides tolerate room temperature for short periods, such as during shipping, but they keep best refrigerated or frozen. Once reconstituted, peptides should always be kept refrigerated.

Cold slows the chemical reactions that degrade peptides: hydrolysis of the peptide bonds, oxidation of methionine, cysteine and tryptophan, deamidation of asparagine and glutamine, and aggregation. In solution, cold also slows the growth of any microbes. These reactions happen far faster in solution than in dry powder.

Lyophilized peptides typically remain stable for months at 2–8 °C, and for a year or more frozen at −20 °C. Reconstituted peptides are usually kept refrigerated and used within a few weeks. Stability varies by sequence, so check the vial label and Certificate of Analysis.

Properly sealed and kept frozen at −20 °C or colder, most lyophilized peptides remain stable for years. At refrigerator temperature, months is typical. Moisture is the main threat, so keep vials sealed until use and let them warm to room temperature before opening.

Much less time than as a dry powder. Most reconstituted peptides are kept refrigerated at 2–8 °C and used within a few weeks; the exact window depends on the peptide's sequence, the diluent, and how carefully the vial is handled. Avoid repeated freeze-thaw cycles and light exposure.

Let the sealed vial reach room temperature so moisture does not condense inside. Disinfect the stopper with alcohol, then add the chosen sterile diluent slowly down the inside wall of the vial rather than directly onto the powder. Swirl or roll gently until dissolved; do not shake. The resulting concentration is the peptide's labeled mass divided by the volume added. Label the vial with the date and concentration and store it refrigerated.

Lyophilized peptides are stable enough to ship at ambient temperature for the few days of a typical delivery. We ship temperature-sensitive items quickly with cold packs. Refrigerate vials as soon as they arrive.

Cloudiness usually means the peptide has not fully dissolved or has started to aggregate. Common causes are adding diluent too quickly, a concentration that is too high, a diluent too cold or at the wrong pH for that peptide, and shaking. Let the vial reach room temperature and swirl gently. A solution that stays cloudy should not be used; contact us with the lot number.

Sealed lyophilized peptides generally tolerate room temperature for days to a few weeks, which is why they can travel without refrigeration, but they should be moved to the fridge or freezer for storage. Reconstituted peptides are much less stable at room temperature and should go back into refrigeration promptly after handling. Heat, light and humidity all speed up degradation, and stability varies by sequence, so follow the vial label and Certificate of Analysis.

Sealed lyophilized peptides keep longest frozen at −20 °C or colder, where most remain stable for a year or more, often several years. Keep vials in a closed container with desiccant and let them reach room temperature before opening. Avoid frost-free freezers, which warm up periodically. If a reconstituted solution must be frozen, divide it into single-use aliquots first, because repeated freeze-thaw cycles promote aggregation and degradation.

Keep vials at 2–8 °C in the main body of the refrigerator, not the door, where the temperature swings each time it opens. Store them upright in a closed box or bag to keep out light and moisture, and away from the freezer compartment. Label reconstituted vials with the date and concentration, and let a sealed powder vial reach room temperature before opening it so condensation does not form inside.

Yes. Peptides degrade slowly even as a dry powder and much faster in solution, so suppliers assign an expiration or retest date based on stability data and storage conditions. As a guide, sealed lyophilized vials last months refrigerated and a year or more frozen, while reconstituted solutions are usually used within a few weeks. Material past its date, or showing discoloration, cloudiness or powder clumped by moisture, should be retested or replaced.

Gelling happens when peptide chains associate with each other and trap water, forming a viscous or jelly-like solution. It is more likely with hydrophobic or β-sheet-forming sequences, at high concentration, near the peptide's isoelectric point (where its net charge is close to zero), in cold diluent and after shaking. Reconstituting at a lower concentration, adding diluent slowly down the vial wall and swirling gently usually help; some peptides need a different diluent. Contact us with the lot number if a vial will not dissolve.

Reconstitution simply dissolves a dry powder in a diluent to make a solution of known concentration. Compounding is a regulated pharmacy practice in which a licensed pharmacist or registered outsourcing facility combines or alters ingredients to prepare a medication for a patient. Dissolving a research peptide in the laboratory is reconstitution, not compounding, and research reagents are not medicines.