Frequently Asked Questions — Research Peptides, Quality, Ordering & Storage

Research peptides are short chains of amino acids synthesized for laboratory study. Most are between 3 and 50 residues, joined by amide bonds, and are investigated for their activity at specific receptors or within named signalling pathways — metabolic, endocrine, regenerative. Peptide.Express supplies them as lyophilized powder for in-vitro research use only.

Chain length, and what that length does to structure. Peptides are short — conventionally under about 50 amino acids — and generally lack a stable folded tertiary structure. Proteins are longer and fold into defined three-dimensional shapes that their function depends on. The boundary is a convention rather than a hard chemical line: insulin at 51 residues sits right on it and gets called both. The practical consequence is that peptides are chemically synthesizable residue by residue on a solid-phase resin, while proteins usually require expression in a biological system.

A blend is a single vial containing two or more separately synthesized peptides, combined at a fixed ratio and lyophilized together. KLOW is a four-component blend of KPV, GHK-Cu, BPC-157 and TB-500; the Wolverine Blend pairs BPC-157 with TB-500. Each component is purity-tested to ≥99% on its own before blending, and the finished vial is checked for compositional ratio. Blends behave differently from their components during reconstitution — the constituent peptides can differ several-fold in molecular weight and dissolve at different rates.

Synthetic. All compounds are produced by solid-phase peptide synthesis, then purified by preparative chromatography and lyophilized. Several are synthetic versions of molecules that occur endogenously — GHK-Cu is present in human plasma, MOTS-c is encoded in mitochondrial DNA — but the material in the vial is chemically synthesized, not extracted from tissue.

The catalog covers 30+ research-grade compounds across the main research categories: incretin receptor agonists (retatrutide, tirzepatide, semaglutide), growth hormone secretagogues and GHRH analogs (tesamorelin, CJC-1295, ipamorelin, sermorelin), regenerative and repair compounds (BPC-157, TB-500, GHK-Cu, KLOW, Wolverine Blend), mitochondrial compounds (MOTS-c, SS-31, NAD+), and melanocortin peptides (PT-141, Melanotan II). Every compound is HPLC-verified to ≥99% and ships with a batch-specific CoA.

Yes. Research peptides are legal to purchase online in the United States for legitimate laboratory research. Peptide.Express ships to all 50 US states via USPS Priority Mail, with same-day dispatch on orders placed before 2PM EST. All purchases are subject to our research-use-only policy.

BPC-157 (Body Protection Compound-157) is a synthetic 15-amino-acid pentadecapeptide, sequence GEPPPGKPADDAGLV, derived from a protein sequence found in human gastric juice. Molecular weight 1,419.5 Da. It is among the most heavily studied research peptides in preclinical models, with work concentrated on angiogenesis via VEGF upregulation, tendon and ligament repair, and gastrointestinal mucosal integrity. Peptide.Express supplies BPC-157 at ≥99% purity, HPLC-verified, for research use only.

Semaglutide is a GLP-1 receptor agonist structurally derived from the human incretin hormone GLP-1, modified for extended plasma half-life. Research has examined its effects on glucose homeostasis, gastric emptying and appetite signalling.

Retatrutide (LY3437943) is an investigational triple receptor agonist targeting GLP-1R, GIPR and the glucagon receptor simultaneously. It is in Phase 3 trials and is not approved for any indication. Preclinical and Phase 2 work has focused on energy balance and adipose tissue metabolism. Supplied as a research compound only.

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH). Research has studied its effect on pituitary GH secretion and its extended half-life relative to native GHRH, which is measured in minutes. Peptide.Express supplies CJC-1295 verified to ≥99% purity by HPLC, for research use only.

Ipamorelin is a selective growth hormone secretagogue and ghrelin receptor (GHS-R1a) agonist. Its research interest comes largely from its selectivity — it stimulates GH release with little effect on cortisol or prolactin, unlike earlier secretagogues in the same class. Available at ≥99% purity with a CoA.

It means at least 99% of the peptide material in the vial, measured as area under the curve on an HPLC chromatogram, corresponds to the target peptide. The remaining fraction is typically truncated or deletion sequences from incomplete coupling steps, residual synthesis reagents, or counter-ions such as trifluoroacetate. Purity is a proportion — it says how much of the sample is the target peptide, not what the rest of it is.

High-Performance Liquid Chromatography separates a sample by pushing it through a packed column under pressure. For peptides the standard is reverse-phase C18: molecules elute in order of hydrophobicity into a detector, which records absorbance over time as a chromatogram. Purity is calculated by integrating the target peak area against the total peak area on the trace.

Liquid chromatography coupled to tandem mass spectrometry confirms molecular identity. It measures the mass-to-charge ratio of the eluting compound and compares it against the theoretical molecular weight of the named peptide. HPLC establishes that one species dominates the sample; LC-MS/MS establishes which species that is. The two are not interchangeable, which is why both run on every batch.

Purity is a proportion; identity is a fact about the molecule. A sample can be 99.5% pure and still be the wrong compound — the chromatogram would look perfect. TB-500 is the standing example: the name is applied to full-length synthetic Thymosin β-4 at 4,963.4 Da and to short LKKTET-motif fragments around 890 Da. Only the mass on the CoA distinguishes them.

A CoA is the batch record for one specific synthesis run. It carries the compound name, batch or lot number, HPLC purity result and chromatogram, LC-MS/MS mass data, appearance, endotoxin result, test date, and the name of the laboratory that performed the analysis. CoAs are batch-specific rather than product-line documents: the lot number printed on your vial maps to exactly one certificate.

Batch certificates are published in the lab results library and linked from every product page. Match the lot number printed on your vial label to the certificate. If the two do not match, contact [email protected] with the lot number rather than assuming the documents are close enough.

Yes, and we do no in-house purity testing at all. Every purity and identity figure published on this site comes from an independent accredited laboratory named on the CoA. The reason is structural rather than ceremonial: a lab testing its own material has an interest in the result, and an interested party is not a check. Outside testing removes that incentive and produces a verifiable external chain of custody.

Endotoxin testing measures bacterial lipopolysaccharide — the outer membrane fraction of Gram-negative bacteria — using the LAL (Limulus Amebocyte Lysate) assay. It matters because endotoxin is heat-stable and passes through sterile filtration, so a sterile preparation is not automatically a low-endotoxin one. In cell-culture research, endotoxin activates TLR4 signalling and generates inflammatory readouts that have nothing to do with the compound being studied. Results are reported per batch.

Because impurities are not inert. A truncated sequence missing one residue can retain partial receptor affinity and skew a binding assay; residual trifluoroacetate is cytotoxic to some cell lines at concentrations that appear in poorly purified material. An experiment run on 90% pure peptide is an experiment on an uncharacterized mixture, and its results are not reproducible by anyone using a different lot.

Credit and debit cards (Visa, Mastercard and American Express), Apple Pay and Google Pay, cryptocurrency, and Venmo. Card and wallet payments are handled by our payment provider over an encrypted, PCI-DSS compliant connection, so we never receive or store your full card number.

Contact [email protected] as soon as possible. Orders begin processing immediately, so the window is short. Once an order has shipped, modification is no longer possible and all sales are final.

Yes. Volume-based pricing is available for research institutions and laboratories. Email [email protected] with your requirements and institution details for a quote.

Yes — an email confirmation with your order number, itemized summary and estimated processing time, followed by a second email carrying tracking information once the order ships.

All orders ship from within the United States. Orders placed before 2PM EST dispatch the same business day.

Standard domestic orders are processed within 1-2 business days and typically arrive within 3-5 business days via USPS Priority Mail. Expedited options are available at checkout. Processing can run longer during high-volume periods.

Compounds ship as lyophilized powder in sealed vials, which is far more transport-stable than a solution would be. Vials are placed in protective packaging with temperature-stable insulation. All shipments use discreet, unmarked outer packaging.

Free standard shipping applies to US orders over $150. Below that threshold a flat-rate fee is calculated at checkout based on location and selected speed.

Not currently — Peptide.Express ships within the United States only.

All sales are final once a product has shipped. Research compounds cannot be returned to inventory after leaving our facility because the storage chain can no longer be documented, and an undocumented storage history makes the material unusable for anyone else. Damaged or incorrect orders are handled separately — report those within 48 hours of delivery.

Photograph the vial and the outer packaging before discarding anything, then email [email protected] within 48 hours of delivery with your order number and the lot number from the label. Do not attempt to reconstitute or use material from a vial with a cracked body, a compromised septum, or a lifted crimp seal — a breached seal means the lyophilized cake has been exposed to atmospheric moisture and the material is no longer characterized by its CoA. Replacement or store credit is issued once the report is reviewed.

Refunds are issued for verified damaged or incorrect shipments. All other sales are final. Approved refunds return to the original payment method within 5-10 business days.

Lyophilization is freeze-drying under vacuum: the material is frozen, then the ice is removed by sublimation without passing through a liquid phase. What remains is a dry porous cake. Peptides ship this way because water is what degrades them — hydrolysis of the amide backbone, oxidation of methionine and cysteine residues, and deamidation of asparagine and glutamine all need water to proceed. A lyophilized peptide at -20°C is stable for 24 months. The same peptide in solution at room temperature can degrade measurably within days.

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol (9 mg/mL) as a preservative. Bacteriostatic means it inhibits bacterial growth rather than killing bacteria outright — the distinction is the whole point. That inhibitory action is what permits repeat access to a vial for up to 28 days under USP guidance. Sterile water for injection contains no preservative and is single-use: once the septum has been punctured, there is nothing preventing growth of anything introduced.

Bacteriostatic water covers the majority of catalog compounds. A few require something else — peptides with poor aqueous solubility may need a small volume of dilute acetic acid or DMSO before dilution into aqueous buffer. Check the product documentation or the CoA for compound-specific guidance rather than assuming bacteriostatic water works universally.

Bring the vial to room temperature, calculate the diluent volume for your target concentration, swab the septum with alcohol and let it dry, then inject the bacteriostatic water slowly down the inner wall of the vial rather than onto the cake. Swirl gently for 60-90 seconds until the solution runs clear. Never shake or vortex. Label the vial with the date and concentration before it goes into the fridge.

Reconstituted in bacteriostatic water and held at 2-8°C, protected from light, the working window is generally 14-28 days. The upper end tracks the USP 28-day multi-dose limit for benzyl alcohol-preserved vials rather than the chemical stability of any particular peptide. Some compounds are less forgiving than others, and a solution that has gone cloudy, discoloured or particulate is finished regardless of what the calendar says.

It is possible but rarely the right call for a vial in active use. Each freeze-thaw cycle concentrates solutes at the advancing ice front and drives peptide aggregation at the ice-water interface, and repeated cycling is one of the more reliable ways to lose material. If a reconstituted solution must be held longer than the refrigerated window, aliquot it into single-use volumes first so nothing is thawed twice. Refrigeration at 2-8°C is the better default.

At -20°C, desiccated and protected from light, for long-term storage. For under 30 days, 2-8°C is acceptable. Keep vials sealed until reconstitution — the lyophilized cake is hygroscopic and will pull atmospheric moisture the moment it is exposed.

Stored properly at -20°C, 24 months from manufacture is the standard shelf life across the catalog, and many compounds remain within specification beyond it. Reconstituted material is a different question entirely — that window is 14-28 days refrigerated.

No. Every product sold by Peptide.Express is for in-vitro laboratory research and educational use only. Nothing on this site is intended for human consumption, clinical administration, or veterinary use.

It means the material is characterized for laboratory work and nothing else. Research-use-only compounds are not manufactured under the pharmaceutical GMP requirements that apply to drug products, are not sterile-filled for injection, and carry no approval from any regulatory body for administration to humans or animals. The CoA documents purity and identity — it is not a safety assessment, and it says nothing about what the compound does in a living organism. Purchasing carries an agreement that the material stays in that context.

No. No compound supplied by Peptide.Express is an FDA-approved drug product. A few of the molecules in the catalog exist in approved pharmaceutical form elsewhere — tesamorelin is approved as Egrifta for HIV-associated lipodystrophy, and semaglutide and tirzepatide are approved under brand names — but an approved drug and a research-grade compound of the same molecule are different products with different manufacturing standards. Others, including retatrutide, are investigational and not approved for any indication anywhere.

Several compounds in the catalog appear on the WADA Prohibited List and are banned at all times, in and out of competition. BPC-157, TB-500 and MOTS-c fall under S0/S2 as non-approved substances and peptide hormones or growth factors. Growth hormone secretagogues and GHRH analogs — tesamorelin, CJC-1295, ipamorelin, sermorelin — are prohibited under S2. Enclomiphene, as a selective estrogen receptor modulator, falls under S4. The Prohibited List is revised annually, so competitive athletes and the people advising them should check the current version at wada-ama.org rather than relying on any vendor summary.

In most cases no special license is required to purchase research peptides in the United States, though buyers must confirm the material will be used for legitimate research. Some compounds are subject to jurisdiction-specific rules. Verifying local law before ordering is the buyer's responsibility.

Peptide.Express supplies material for in-vitro laboratory research only and makes no representation about suitability for in-vivo work. Research-use-only material is not sterile-filled and is not manufactured to any veterinary standard. Any animal research is governed by the investigator's institutional animal care and use committee, and sourcing decisions for that work sit with the institution, not with us.