Choosing a Research-Grade Peptide Supplier: A Checklist
Not all research suppliers document their materials to the same standard. Here are the questions that separate a verifiable supplier from a vendor asking you to take purity on faith.
By LOCKED Research Team · Quality & Compliance
Research Use Only. This article is educational and does not constitute medical advice or a claim of safety or efficacy. LOCKED products are supplied for laboratory research use only (RUO). They are not drugs, foods, dietary supplements, cosmetics, or medical devices, are not for human or animal consumption, and are not intended to diagnose, treat, cure, or prevent any disease. LOCKED makes no medical, therapeutic, or performance claims. The purchaser is solely responsible for compliance with all applicable laws and for lawful use.
The research market is crowded, and the visible differences between suppliers — site design, pricing, product range — are the least important ones. What matters is whether a supplier can prove what it sells. Use this checklist to evaluate any research-grade peptide source.
1. Is there a Certificate of Analysis for every batch?
The baseline. A supplier should provide a batch-specific COA, not a generic specification sheet. If the same document is attached to every lot regardless of when it was made, it is a spec, not a certificate.
2. Is purity reported as a number, with a method?
Look for an exact percentage tied to a named method — typically RP-HPLC. "High purity" and "lab tested" without a figure are marketing, not measurement.
3. Is identity confirmed independently of purity?
Purity tells you how much; identity tells you what. A complete supplier confirms identity by mass spectrometry, so a clean peak is also the right peak.
4. Is testing third-party?
In-house numbers have a conflict of interest baked in. Accredited third-party testing means the purity figure was produced by a party with no stake in the outcome.
5. Can you verify a lot number?
A trustworthy supplier lets you resolve a batch or lot number to its certificate — ideally through a public lookup, not an email request. Traceability that only the seller can perform is not traceability.
6. Is the Research-Use-Only boundary respected?
This is a tell. A supplier that describes what a compound does in a person — effects, outcomes, dosing — has left the research lane and is making unapproved claims. A disciplined supplier documents identity and purity and stops there. That discipline usually correlates with quality everywhere else.
7. Is handling documented?
Storage conditions and cold-chain practices should be stated, not assumed. The best purity in the world doesn't survive a warm, undocumented supply chain.
The through-line
Every item on this list reduces to one question: can the supplier prove its claims, or is it asking for trust? LOCKED is built around the first answer — batch-specific COAs, HPLC purity figures, mass-spec identity, third-party testing, and public lot verification. Hold every supplier, including us, to the checklist.