What a Real EV COA Contains: Seven Items and the Red Flags That End the Call

The COA is the most honest document your supplier will hand you — if you know how to read it. Seven items separate a COA you can build a brand on from a PDF you should walk away from.

1. Batch identification and traceability. Every value on the COA must resolve to one batch — with a code that links to culture records, purification logs and retain samples. A COA without a resolvable batch ID is a flyer.

2. Particle-size distribution, method named.

[Figure caption] An actual NTA curve from a TONGNIAN batch — single distribution, method-anchored. Item 2 should look like this. NTA values with the method and instrument class stated, cross-checked by TEM morphology. A size range without a method is a decoration. Best practice anchors to a published measurement guideline — ours follows national guideline 2026 No. 17, which TONGNIAN helped draft.

3. Particle concentration. Stated per mL with the measurement basis, inside configurable tiers (5–100 billion particles/mL on a documented line). "Enriched" is not a number.

4. Endotoxin, with the limit. LAL-based endotoxin values with the release limit printed — "tested" alone proves nothing.

5. Sterility and microbial limits. Membrane-filtration sterility plus microbial limits, negative on release.

6. Payload or purity check. A protein/marker payload or purity figure with the check described — the item most often missing on adjective-only products.

7. Retain-sample statement. The COA should say samples are retained per batch — the difference between a document and an audit trail.

The red flags that end the call: no method names, no release limits, no batch ID, "proprietary blend" in place of payload, and a COA that only arrives after the order — never before you commit.

Every TONGNIAN batch ships with a COA carrying all seven — request a sample COA and read one before you buy.