Short answer: A genuine Certificate of Analysis (COA) shows three things for a specific batch, not the product in general: the purity percentage confirmed by HPLC, the molecular identity confirmed by mass spectrometry, and a batch number that ties the document to the exact vial you’re holding. If a “COA” is missing any of these three, is undated, or uses a batch number that never changes across different orders, it isn’t proof of anything — it’s a marketing graphic.

Most people buying research peptides in the UK have never actually been shown how to check one. Here’s what to look for.

What a COA is actually testing for

A Certificate of Analysis is a lab report, not a quality seal a supplier writes themselves. It should be issued by a third-party lab — independent of the peptide manufacturer and the retailer — and it typically covers three separate tests:

1. Purity, via HPLC (High-Performance Liquid Chromatography). HPLC separates a sample into its component compounds and measures what percentage of the total is the actual peptide versus leftover synthesis by-products, solvents or degraded fragments. This is reported as a percentage — reputable research peptides are usually tested to 98%+ purity. A COA that states purity without showing the underlying chromatogram graph is weaker evidence than one that includes it.

2. Identity, via mass spectrometry (MS). Purity alone doesn’t confirm you’ve got the right peptide — a sample can be 99% pure and still be the wrong molecule entirely. Mass spec measures the molecular weight of the sample and compares it against the expected weight for that peptide’s amino acid sequence. This is the test that actually confirms “this vial contains BPC-157” rather than “this vial contains something consistent, at 99% purity.”

3. Sterility and endotoxin testing (for lyophilised products intended for research reconstitution). This checks for bacterial contamination and endotoxins that can occur during freeze-drying or vial-filling. Not every supplier includes this, but its presence is a meaningful marker of a lab taking handling seriously.

The five-point COA checklist

Before trusting any COA a supplier shows you, check for these:

• Batch or lot number that matches the number printed on the vial or box you received — not a generic number reused across every batch the company sells
• Test date, ideally within a reasonable window of the product’s manufacture date, not a document that’s years old and reused indefinitely
• Named testing laboratory, ideally one independent of the manufacturer, with contact details or accreditation you can verify
• Both HPLC and mass spec results shown, not just a purity percentage typed into a template
• Raw chromatogram/spectrometry graphs included, not only a summary number — graphs are far harder to fabricate convincingly than a typed percentage

If a supplier can’t produce a document meeting most of these points on request, that’s information in itself.

Red flags in a COA

A few patterns are worth treating as warning signs rather than nitpicks:

• The same COA image reused across multiple different products. Genuine batch testing produces a new document per batch; a purity certificate that’s identical, pixel-for-pixel, across a supplier’s entire catalogue is not batch-specific and proves nothing about the vial you bought.
• No named lab, or a lab that doesn’t appear to exist independently. Search the lab name — legitimate third-party testing facilities have a public presence, accreditation, and usually other clients.
• Purity reported with no supporting data. “99.2% pure — tested via HPLC” with no graph, no batch number and no date is a claim, not a certificate.
• A COA date that predates the product’s apparent manufacture, or one that’s suspiciously old. Peptides degrade over time even when stored correctly, so a certificate from years ago tells you nothing about current stock.

Why this matters more in the UK peptide market specifically

Because research peptides are sold as, well, research chemicals rather than regulated medicines, there’s no equivalent of an MHRA product licence guaranteeing consistency batch to batch. The COA is effectively the only independent verification a buyer has. That makes it worth treating as the single most important document in the transaction — more important than price, packaging, or how professional a website looks. We cover the wider picture of supplier vetting, including company registration and marketing red flags, in UK Peptide Supplier Red Flags: How to Vet Any Vendor Before You Buy, and the legal backdrop for why “research use only” labelling matters in Are Peptides Legal in the UK?.

Frequently asked questions

What does COA stand for in peptides? Certificate of Analysis — a lab document verifying the purity and identity of a specific batch of a product.

What purity percentage should a research peptide have? Most reputable suppliers test to 98% or higher via HPLC. Purity below that isn’t necessarily fake, but it’s worth asking why, and comparing against the batch’s mass spec identity confirmation.

Can a COA be faked? Yes — a typed percentage on a document with no lab name, no batch number and no underlying graph data is easy to fabricate. Graphs, named accredited labs and batch-specific numbering are much harder to convincingly falsify.

Does every peptide supplier provide a COA? No, and that absence is itself useful information. Any supplier unwilling or unable to provide batch-specific third-party testing on request is asking you to trust them with no independent verification at all.

Is HPLC the same as mass spectrometry? No. HPLC measures purity — what percentage of the sample is the target compound. Mass spectrometry measures identity — whether that compound is actually the peptide it’s claimed to be. A complete COA includes both.

---

This article is provided for general informational purposes. All products sold by Alphamino are supplied strictly for laboratory research use only and are not intended for human or animal consumption. Batch-specific COAs for every product we sell are available on request.