Third-party COA verification: a researcher's checklist

A Certificate of Analysis (COA) is the single most important document a researcher receives with a peptide procurement. It's also the document where the difference between a research-grade supplier and a low-quality reseller becomes obvious.

This is a practical checklist. Every researcher building a procurement standard should have something like it.

What a real COA contains

A research-grade COA, issued by an independent analytical laboratory, will include at minimum:

1. Lot/batch identifier that matches the lot number printed on the vial received
2. Date of analysis, which should be reasonably recent (within 12 months for stable peptides, sooner for less stable compounds)
3. Identity confirmation via mass spectrometry showing the expected molecular weight
4. Purity measurement via HPLC (typically RP-HPLC), reported as a percentage with the chromatogram included or available on request
5. Net peptide content, distinct from mass-of-vial weight
6. Issuing laboratory name, address, and signature — independent of the seller
7. Method documentation — at least the column type, mobile phase, and detection wavelength used

Red flags

A COA that's missing any of the above, or that displays any of the following, should be treated as inadequate:

• Self-issued by the seller — no independent third-party laboratory listed
• No lot number, or lot numbers that suggest the same COA is reused across batches
• Purity reported as "≥99%" with no chromatogram and no method detail. The chromatogram is the evidence; the percentage alone is a claim
• Stated mass of vial without net peptide content — common for low-quality sources, where the actual peptide content can be 70–80% of stated weight after counter-ions and water
• Dates more than 18 months old for stable peptides, or any age for unstable compounds
• Identity confirmation missing or implausible — mass spectrometry data should match published molecular weight to within reasonable tolerance

What to ask before procurement

The most useful procurement question is simple: "Can you send me the lot-specific COA, issued by a third-party analytical laboratory, for the specific batch you'll be shipping?"

A research-grade supplier will produce that document quickly and routinely. A reseller dropshipping unverified product will not.

Two follow-up questions worth asking:

• "Which third-party lab issued the COA?" — should be a recognizable analytical laboratory
• "What were the test conditions?" — should be a specific HPLC method, not a vague answer

Independent labs commonly cited in research peptide COAs

The space of analytical laboratories that issue peptide COAs is small. Researchers procuring research peptides will frequently see COAs from labs like:

• Janoshik Analytical
• Freedom Diagnostics
• Eurofins (when contracted)

Cross-reference any COA against the issuing lab's website if you have any reason to question authenticity. A real lab will respond to direct verification requests for lots they've tested.

Storing COAs alongside experimental records

For reproducibility, the COA for the specific lot used in any experiment should be retained alongside the experimental records. If you're publishing or building toward publication, lot-level documentation is the standard. Researchers who treat COAs as throwaway documents tend to discover, the hard way, that they can't reproduce their own results when they switch lot numbers.

Want the full procurement quality checklist?

Our researcher resource pack includes a printable COA checklist, a sample COA with annotations on what each section means, and current notes on which third-party labs are issuing reliable peptide analytical work. Drop your email below if you'd like it.