There are more places than ever to buy research peptides, and most of them look the same from the outside: clean website, long catalog, "99% purity" on every listing. The differences that matter are underneath. Can the supplier prove what's in the vial? Will the material arrive in the condition it left in? Does the supplier behave like a laboratory vendor at all?
This checklist is for labs and researchers choosing where to buy. It doesn't name or rank competitors. Good suppliers exist, and the point is to give you the questions that separate them from the rest. Apply every question to us too.
Why the choice matters
The peer-reviewed literature shows that quality in this market varies widely:
- A study of melanotan II vials from three online shops found 4.32–8.84 mg of peptide in vials sold as 10 mg, plus unknown impurities of 4.1–5.9% in vials from two shops (Breindahl et al., 2015; DOI: 10.1002/dta.1655).
- A systematic screen of falsified peptide products bought from suspected illegal internet pharmacies found purities as low as 5–75% for cysteine-containing peptides, and arsenic and lead contamination (Janvier et al., 2018; DOI: 10.1016/j.talanta.2018.06.023).
- A 2025 systematic review of one widely discussed research peptide noted that adverse effects are possible due to "unregulated manufacturing, contamination, or unknown clinical safety" (Vasireddi et al., HSS Journal, 2025; DOI: 10.1177/15563316251355551).
For a laboratory, a mislabeled, under-filled or contaminated vial means results that can't be reproduced, or worse, results that look fine and are wrong. Supplier choice is part of experimental design.
The checklist
Part A — Proof of what's in the vial
1. Is every vial lot-numbered? The lot number is the thread that connects a vial to its test results. No lot number, no traceability. This is the minimum.
2. Is there a test record for your lot, not a "representative" one? A single certificate reused across batches tells you about one batch. Ask whether you can pull up the record for the exact lot printed on your label.
3. Can you see the record yourself, without asking? A record you can open by typing a lot number is better than a PDF that arrives by email "on request." Self-service access means the supplier committed to the record before you bought.
4. Does the record include identity, not just purity? HPLC purity shows that one component dominates the sample. It doesn't show that the component is the right molecule. Look for mass spectrometry (LC-MS), with an observed mass that matches the theoretical one. Control laboratories handle identity and quantity as separate measurements, for good reason (Vanhee et al., 2015; DOI: 10.1016/j.talanta.2015.04.022).
5. Does the record show the evidence behind the numbers? A chromatogram and a mass spectrum, a named testing laboratory and a test date. A typed number alone is a claim.
6. Is endotoxin tested? For cell-based work especially, bacterial endotoxin can confound results. Look for a numeric LAL result against a stated limit.
7. Bonus: net peptide content, water and counterions. Lyophilized powder is never 100% peptide. It also holds residual water and counterions such as trifluoroacetate from synthesis. Suppliers that report these are telling you how much of the powder is actually peptide. The Breindahl findings show why that matters.
Part B — Condition on arrival
8. Is the storage condition stated clearly, and consistently? The label, the box and the product page should all say the same thing. Inconsistency suggests nobody is really managing it.
9. How is the material packed and shipped? Look for vials secured so they can't move, material shipped dry and sealed, and tracked shipping so you can receive the parcel promptly. Published stability work on lyophilized biologics has shown that shipping-like shaking stress can break the freeze-dried cake and reduce physical stability during later storage (Telikepalli et al., 2015; DOI: 10.1002/jps.24242). That study used a large protein rather than a short peptide, but the handling principle carries over.
10. What happens if something goes wrong in transit? A clear, written policy for lost, damaged or delayed parcels tells you the supplier expects to be held accountable.
Part C — How the supplier behaves
11. Does the supplier act like a laboratory vendor? A genuine research-use-only supplier:
- describes compounds by name, strength, form and container, not by promised outcomes;
- makes no health, performance or appearance claims;
- gives no advice on use outside the laboratory;
- requires buyers to confirm research use.
Suppliers that market results to individuals are telling you who they're really selling to. That usually says something about their quality controls too.
12. Can you tell who you're buying from? A named legal entity, a working support address and published policies (shipping, returns, research use) are signs of an accountable business.
Scoring it
A simple way to compare suppliers:
| # | Question | Yes / No |
|---|---|---|
| 1 | Every vial lot-numbered | |
| 2 | Record for your specific lot | |
| 3 | Record self-service, not "on request" | |
| 4 | Identity data (LC-MS) | |
| 5 | Chromatogram, spectrum, lab name and date shown | |
| 6 | Endotoxin tested, numeric result | |
| 7 | Net content, water, counterion reported | |
| 8 | Storage condition clear and consistent | |
| 9 | Secure, dry, sealed, tracked shipping | |
| 10 | Written transit-problem policy | |
| 11 | Behaves as a research vendor, no outcome claims | |
| 12 | Named entity, published policies |
No supplier is perfect on every line. The ones worth using answer the Part A questions with evidence, not adjectives.
Questions to send a supplier before your first order
If a supplier's website doesn't answer the checklist, ask directly. These questions are short, specific and hard to dodge:
- "Can you send the record for the exact lot you'd ship me, before I order?"
- "Which laboratory ran the analysis, and on what date?"
- "Does the record include LC-MS identity, with the observed mass?"
- "Can I see the HPLC chromatogram, not just the purity figure?"
- "Is endotoxin tested? What's the numeric result and the limit?"
- "Do you report net peptide content, water or counterion?"
- "How are vials packed, and what's the storage condition on the label?"
- "What happens if a parcel is delayed or arrives damaged?"
How a supplier answers tells you as much as what it says. A specific answer that arrives quickly, with a document attached, is a good sign. So is "we don't test for that yet," which at least tells you where the gap is. Vague reassurance ("all our products are 99%+ pure"), a refusal to name the laboratory, or a reply that pivots to what the compound "does" are all reasons to keep looking.
Common mistakes when choosing a supplier
- Choosing on price alone. Synthesis, purification and independent testing cost money. The cheapest listing is often the one with the least testing behind it.
- Reading "99% purity" as the whole story. It says nothing about identity, content or contaminants such as metals, the exact problems documented in the Janvier and Breindahl analyses above.
- Trusting reviews over records. A review can tell you the parcel arrived. It can't tell you what was in the vial.
- Not logging the lot. If you don't record which lot you used, you can't trace an unexpected result back to the material later.
Verify, don't trust
Two habits make any supplier choice safer:
- Match the lot. When a vial arrives, open the record for that exact lot and compare the compound, strength and lot number.
- Confirm independently for critical work. An LC-MS identity check at your institution or a contract lab is the same approach official control labs use. If a supplier's records are genuine, independent testing will agree with them.
Where Seratide stands on this checklist
We built Seratide around Part A, because proof is the thing this market most often lacks. We'd rather state plainly where we are than overstate it.
- Lot-numbered vials. Every vial carries a lot number in the form SRT-0000-XXX.
- A self-service record per lot. Type the lot number on our Lot lookup page to open that lot's record. There's no login, and every record has a permanent, shareable link.
- The record format covers HPLC purity (specification and result), identity by LC-MS, endotoxin (LAL), and the testing laboratory and date.
- Honest status: the records on the Lot lookup page today are clearly labeled layout samples. They show the format, and their values are placeholders, not measurements. Issued laboratory reports replace them as each lot is analyzed. Hold us to that.
- Shipping: stock is kept frozen at our warehouse; vials ship dry and sealed at room temperature (no ice packs) by tracked US carrier, packed so they can't move. Refrigerate them (2–8 °C) on arrival. The details are in our Shipping Policy.
- Research use only, and we mean it. Our listings give compound, strength, form, container and lot, with no outcome claims. We sell only to buyers aged 21 or older who confirm laboratory research use. Read our Research Use Only policy.
Whichever supplier you choose, use the checklist. The good ones will be glad you asked.
Sources
All sources below were opened and checked against their PubMed records while drafting.
- Breindahl T, et al. Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet. Drug Test Anal. 2015;7(2):164-72. PubMed: https://pubmed.ncbi.nlm.nih.gov/24771717/ · DOI: https://doi.org/10.1002/dta.1655
- Janvier S, et al. Impurity profiling of the most frequently encountered falsified polypeptide drugs on the Belgian market. Talanta. 2018;188:795-807. PubMed: https://pubmed.ncbi.nlm.nih.gov/30029448/ · DOI: https://doi.org/10.1016/j.talanta.2018.06.023
- Vasireddi N, et al. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review. HSS J. 2025;21(4):485-495. PubMed: https://pubmed.ncbi.nlm.nih.gov/40756949/ · DOI: https://doi.org/10.1177/15563316251355551
- Vanhee C, et al. Analysis of illegal peptide biopharmaceuticals frequently encountered by controlling agencies. Talanta. 2015;142:1-10. PubMed: https://pubmed.ncbi.nlm.nih.gov/26003685/ · DOI: https://doi.org/10.1016/j.talanta.2015.04.022
- Telikepalli S, et al. Characterization of the physical stability of a lyophilized IgG1 mAb after accelerated shipping-like stress. J Pharm Sci. 2015;104(2):495-507. PubMed: https://pubmed.ncbi.nlm.nih.gov/25522000/ · DOI: https://doi.org/10.1002/jps.24242
For laboratory research use only.