Tirzepatide Certificate of Analysis (COA): How to Read It

What a COA is — and why it matters for Tirzepatide

A Certificate of Analysis is a per-batch lab report a supplier (or an independent lab) issues for a specific lot of Tirzepatide. It documents identity and purity from instrumental testing — typically HPLC for purity and mass spectrometry for molecular identity. Without a batch-specific COA you are trusting a label, not data.

COA freshness matters more for Tirzepatide than for shelf-stable compounds. Refrigerate after reconstitution; manufacturer guidance is 28 days post-reconstitution. Because this compound is in the metabolic category and degrades on the timeline above, a COA tells you about the batch on the day it was tested — not necessarily the vial in your hand months later. That makes a recent test date and proper cold-chain handling part of how you read the document, not an afterthought.

What purity to expect on a Tirzepatide COA

A legitimate Tirzepatide COA should show at least 98% HPLC purity — the benchmark the research community treats as the floor for research-grade material. Anything materially below 98% on Tirzepatide warrants a second batch or a different supplier.

Purity is read off the HPLC chromatogram as the Tirzepatide peak area relative to total peak area. A COA that states a percentage but does not attach the chromatogram is giving you a claim, not evidence — see the red flags below. For the underlying method, our explainer on HPLC and visual guide to reading a chromatogram walk through what a clean Tirzepatide peak should look like.

What a real Tirzepatide COA must show

Run any Tirzepatide COA against this six-point checklist. A document that misses any line is incomplete for verification purposes:

• Compound identity — the document names Tirzepatide (dual GIP/GLP-1 agonist; confirmed by mass spec, not just printed on the page).
• Batch / lot number — a unique identifier tying the COA to the exact lot the vial came from.
• Test date within 6 months — especially important for Tirzepatide, which is refrigerate after reconstitution; manufacturer guidance is 28 days post-reconstitution.
• HPLC purity % — a number at or above the 98% benchmark, with the chromatogram attached.
• Testing lab name — a named third-party lab (see the three labs below).
• Mass spec confirmation — molecular-weight verification proving the vial holds Tirzepatide and not a cheaper or mislabeled substitute.

The 3 labs the community trusts

Not every “lab tested” claim carries the same weight. For research peptides, three independent labs have earned community trust for Tirzepatide and similar compounds:

• Janoshik Analytical — the most widely cited third-party peptide lab.
• MZ Biolabs — frequently used for independent HPLC and mass-spec work.
• Colmaric Analyticals — a recognized name for batch verification.

A Tirzepatide COA from an unnamed or in-house lab is a red flag: there is no independent party to hold accountable, and the result cannot be cross-checked. A named third-party lab is the difference between a COA you can verify and a COA you can only hope is honest. Our deep dive on Janoshik vs MZ Biolabs compares two of them directly.

Red flags on a Tirzepatide COA

Reject — or at minimum re-verify — a Tirzepatide COA that shows any of these:

• Generic, not batch-specific — one COA reused across every order, with no lot number tying it to your vial of Tirzepatide.
• Missing test date — no date at all, so you cannot tell how old the result is.
• Test date older than 6 months — stale data, which matters more for Tirzepatide given its storage profile above.
• No lab name — “tested” with no named third-party lab behind the number.
• Purity claimed, no chromatogram — a percentage with no HPLC trace attached to back it up.

This is reference guidance for evaluating laboratory documentation, not medical or dosing advice. Tirzepatide and all compounds referenced are for laboratory research use only — not for human consumption.

Keep reading

The canonical reference for this whole topic is our guide on how to read a peptide COA — it covers the eight required elements, the independent-verification steps, and which 2026 suppliers ship batch-specific COAs, then links out to the deeper chromatogram, HPLC, and red-flag explainers as you need them.

Working with a Tirzepatide vial directly? Use our Tirzepatide reconstitution calculator to compute concentration per insulin-syringe unit. For background on the compound itself, see our Tirzepatide research guide.

Other compound COA guides

Semaglutide COA guide · Retatrutide COA guide · AOD-9604 COA guide