What does a Certificate of Analysis show?

A Certificate of Analysis (COA) is a third-party laboratory report documenting four things about a specific batch of peptide: identity (confirmed by mass spectrometry), purity (measured by HPLC), endotoxin contamination (measured by LAL assay), and — for injectable products — sterility. Each section is linked to a batch or lot number, a test date, and an identifiable laboratory. A complete COA is the minimum quality record for any research-chem peptide; without it, you're trusting the label without verification.

The four core sections

Every legitimate COA covers these:

A COA missing any one of these is incomplete. A COA missing endotoxin testing is the most common omission — and endotoxin is the most common driver of "side effects" that turn out not to be the peptide at all. See endotoxin testing explained.

Identity — mass spectrometry

Mass spec measures the molecular weight of the compound and confirms it matches the expected molecular weight of the labeled peptide. For BPC-157, the expected mass is around 1419 Da; for TB-500, around 4963 Da; for IGF-1 LR3, around 9117 Da. A mass spec trace showing the correct primary mass — with no other major peaks — confirms identity.

Identity verification is the test that catches counterfeits. A vendor selling "TB-500" that's actually a cheaper short peptide will fail mass spec immediately. A COA without an MS section can't confirm what's in the vial.

Purity — HPLC

High-performance liquid chromatography separates the components in the vial and quantifies the labeled compound as a percent of the total. Typical numbers:

The 1–5% impurity profile matters because impurities can be related peptides, manufacturing residues, or breakdown products. A 96% pure vial isn't 4% saline — it's 4% other molecules that may not be benign. See peptide purity for the chemistry detail.

A purity claim without a chromatogram trace is harder to verify; a chromatogram showing a single dominant peak is the visual confirmation.

Endotoxin — LAL assay

Endotoxin is bacterial cell-wall fragment (lipopolysaccharide) that survives sterilization. Even sub-microgram amounts in injected products produce flu-like reactions: fever, chills, body aches, headache, malaise. Most "this peptide gave me terrible side effects" reports turn out to be endotoxin contamination when investigated.

LAL (Limulus amebocyte lysate) is the standard test, expressed in EU/mg (endotoxin units per milligram of peptide):

Vendors that don't test endotoxin or won't share LAL results: assume the worst, and don't inject the product. A clean LAL result is what separates a vial that's safe to inject from a vial that's a roulette wheel.

Sterility (for injectables)

Sterility testing confirms the absence of viable microorganisms. This is more relevant for some products than others — lyophilized (dry-powder) peptides have low water activity that suppresses microbial growth, but contamination during manufacturing can still occur. Reputable injectable vendors include sterility data; some include it only for specific batches.

A clean sterility result plus a clean endotoxin result is the combination that makes injection acceptably low-risk from a contamination perspective.

Batch number, test date, and lab identification

These three meta-fields turn a COA from decorative into useful:

• Batch / lot number — must match the number printed on your vial. A COA for batch A doesn't tell you anything about batch B.
• Test date — recent matters. A COA from 18 months ago for a batch produced last week is suspect. A COA from this quarter for this batch is meaningful.
• Lab name and address — must be an identifiable third-party laboratory. The lab should have its own website, real services, and clients beyond peptide vendors. "Tested by [our internal lab]" is not third-party.

A COA missing any of these is essentially a marketing document. See the COA reading guide for step-by-step interpretation of a real COA.

What a "good" COA looks like, summarized

A COA that you'd consider acceptable from a research-chem vendor:

• Mass spec trace showing the correct primary peak, no major secondaries
• HPLC chromatogram with a single dominant peak, percent purity quoted (98%+)
• LAL endotoxin result quoted in EU/mg, below the relevant threshold
• Sterility result for injectable products
• Batch number matching the vial
• Test date within the last several months
• Identifiable third-party lab with verifiable independent existence

Numbers presented as a single page of text without traces are easier to fabricate. The chromatograms and mass-spec traces are the backup data that make the numbers trustworthy.

What a COA does NOT tell you

A COA covers what's in the vial at the time of testing. It does not tell you:

• Whether the peptide will work for your specific situation
• Whether subsequent batches will match (each batch needs its own COA)
• Whether the vial was stored correctly after manufacturing
• Whether the reconstituted product is sterile (depends on your technique)
• Whether the product is FDA-approved (separate question)

A clean COA establishes that the vendor is selling what's labeled at acceptable purity. That's the floor for a usable product, not the ceiling.

Related questions

• How do I know if my peptide vendor is legit?
• How do I spot fake peptides?
• Are cheap peptides really worse?
• COA reading guide