Buyer education · research use only
How to verify peptide quality with a COA.
A Certificate of Analysis is the one document that separates a documented compound from a number on a label. But most buyers read the big “99%” and stop — which is exactly the wrong move. This is a plain-English guide to reading a peptide COA the way an analyst would: identity before purity, what the HPLC and mass-spec sections actually prove, third-party versus in-house testing, how to confirm the lot code matches your vial, and the red flags that should end a purchase. It makes no human-use or dosing claims; it is about how to read the paper trail.
The five lines that matter
What a real COA contains — and the shortcut a fake takes.
Every legitimate Certificate of Analysis answers five questions. Run any document you're handed against this table before you trust the purity number on it.
| What to check | What a real COA shows | Red flag |
|---|---|---|
| Identity (MS) | Mass spectrometry confirms the molecule's measured mass matches the theoretical mass of the sequence | A COA with purity but no identity test — purity of the wrong molecule is meaningless |
| Purity (HPLC) | High-performance liquid chromatography reports the percentage of the main peak vs impurity peaks | A bare '99%' with no chromatogram, no method, and no instrument trace |
| Lot / batch code | A unique code tying the document to one specific production batch — and to the code printed on the vial | A generic COA reused across every order, or a code that doesn't match the vial |
| Test date & lab | Who ran the test and when — ideally a named third-party analytical lab | 'Tested' with no lab name, no date, no signature |
| Method reference | The analytical method and column/gradient used, so the result is reproducible | No method at all, or claims that can't be reproduced |
Identity first, then purity — not the other way around
The single most common mistake is reading the big '99%' number and stopping. Purity only tells you how much of the main peak is present; it says nothing about whether that peak is the peptide you ordered. That is what the mass-spectrometry (MS) section is for — it confirms the measured molecular mass matches the theoretical mass of the sequence. A real COA shows both: MS for identity, HPLC for purity. If a document shows a purity percentage with no identity confirmation, the percentage is unanchored.
What a verified supplier looks like →What an HPLC purity number actually means
High-performance liquid chromatography separates a sample into peaks over time. The main peak is your target compound; the smaller peaks are synthesis-related impurities, truncated sequences, or solvents. Purity is the area of the main peak as a percentage of total peak area. A trustworthy COA includes the actual chromatogram — the trace with retention times and peak areas — not just a typed-in number. The chromatogram is the evidence; the percentage is the summary. If you only get the summary, you are being asked to trust, not verify.
Browse documented compounds →Third-party vs in-house testing
In-house testing means the vendor ran the analysis on their own instruments; third-party testing means an independent analytical lab did. Both can be legitimate, but they carry different weight. In-house release testing is the operational baseline — it should be lot-matched and reproducible. A named third-party report adds independent verification, which is the strongest trust signal a research buyer can ask for. The thing that should worry you is neither: a 'COA' with no lab named at all, in-house or otherwise.
See Titan's testing standard →The red flags that should end the purchase
Walk away from any supplier whose documentation includes dosing instructions, human-use language, therapeutic or efficacy claims, before/after results, or 'how to take it' guidance — that language is a compliance red flag, not a quality spec, and it signals a vendor who does not understand the research-use-only boundary. Also walk away from a single generic COA reused across unrelated products, a lot code that doesn't match the vial, or a refusal to share the chromatogram. Real documentation is specific, lot-matched, and silent on human use.
Full supplier checklist →The verification loop, in order
Four steps, every order.
- 1. Confirm identity. Find the mass-spectrometry section and check that the measured mass matches the theoretical mass for the sequence. No identity test means the purity number is meaningless.
- 2. Read the purity from the chromatogram. Look for the HPLC trace, not just the percentage. The main peak should dominate; impurity peaks should be small and few. The chromatogram is the evidence behind the number.
- 3. Match the lot code. The batch code on the COA must match the code on the vial you received. This is the step most buyers skip and the one that actually closes the loop.
- 4. Scan for compliance red flags. Any dosing, human-use, or efficacy language in the documentation is a reason to walk away — not because the molecule is wrong, but because the vendor is.
Titan publishes a lot-matched release sheet referenced to the code on each vial, with an HPLC purity target and mass-spec identity confirmation, and keeps all product documentation silent on human use. That is the standard this guide is written to — read it, then verify it yourself.
Related reading
Verify before you buy.
Know what to look for. Then buy from a lab that shows it.
Every Titan compound ships with lot-matched release documentation and an HPLC purity target. Browse the catalog and read the paper trail on each product page.