What Does an Exosome COA Actually Tell You?
A practical breakdown of exosome Certificates of Analysis — what the tests mean, what to look for, and how to spot a template.
If you’ve requested documentation from an exosome supplier, you’ve probably received a Certificate of Analysis (COA). But unless you know what to look for, a COA can look authoritative while revealing very little.
Here’s what every section of a real exosome COA means — and how to tell a thorough, batch-specific report from a generic template.
1. Lot Number & Batch Identification
The single most important field. A real COA is tied to a specific batch by a unique lot number. This lot number should match what’s printed on the vial you receive.
What to look for: A specific alphanumeric lot identifier (e.g., “EUR-2026-07-001”), not “Batch 1” or “Standard Product.”
Red flag: The supplier offers “a COA from last year’s batch as representative.” Every batch is different.
2. Sterility Testing (USP <71>)
Sterility testing confirms the absence of viable microorganisms. The USP <71> standard is a 14-day incubation test — it takes two weeks to confirm sterility because slow-growing organisms need time to become detectable.
What to look for: “No growth detected after 14 days” or “Sterile per USP <71>." The testing lab name should be visible.
Red flag: “Sterility tested” without a reference standard, test duration, or lab name. A 24-hour test cannot rule out microbial contamination.
3. Endotoxin Testing (USP <85>)
Endotoxins are fragments of bacterial cell walls that can trigger inflammatory responses. USP <85> (the Limulus Amebocyte Lysate or LAL test) is the accepted standard.
What to look for: A numerical result in Endotoxin Units per milliliter (EU/mL). The acceptable threshold for biologic material is typically <5 EU/mL.
Red flag: “Pass” or “Compliant” without a numerical value. A COA should report the actual measured result, not just a pass/fail.
4. Identity Testing
Identity testing confirms the material is what it claims to be. For MSC exosomes, this typically involves characterization methods like cytokine array analysis, mass spectrometry proteomics, or NanoSight NTA particle analysis.
What to look for: A description of the characterization method and the specific markers or parameters measured.
Red flag: No identity testing method described, or a vague “product identity confirmed” with no methodology.
5. Who Issued the COA?
This is the most overlooked field — and the most important for trustworthiness.
A COA issued by an independent third-party lab (like Eurofins, Nelson Labs, or another CLIA-certified facility) carries more weight than a COA issued by the manufacturer’s own quality control lab. The reason is simple: an independent lab has no financial incentive to pass a failing batch.
What to look for: The lab’s name, CLIA certification number or laboratory accreditation, and a signature or authorized representative.
Red flag: “Issued by our quality assurance department” with no external lab involvement. This isn’t necessarily disqualifying, but it means the COA is self-published.
6. Expiration and Storage Conditions
A proper COA specifies storage conditions (e.g., “Store at 2-8°C”) and the expiration date or retest date for that batch.
What to look for: Specific temperature range and expiration date. For lyophilized products, room-temperature stability may be specified.
Why B&H Bio Uses Eurofins
B&H Bio ships every batch with an independent Eurofins Certificate of Analysis. Eurofins is a CLIA-certified, global laboratory network with no financial relationship to our manufacturing process. Their COA covers sterility (USP <71>), endotoxin (USP <85>), and identity for every batch we ship — and you can review it before you place an order.