Third-party testing, explained

Third-party testing means the analytical work is done by an independent, accredited laboratory rather than by the party selling the material. Independence is the whole point: a lab with no stake in the result has no incentive to round a number up, and an accreditation such as ISO 17025 means its methods and competence have themselves been audited.

For a given lot, that lab establishes identity by mass spectrometry, purity by reverse-phase HPLC, and endotoxin by LAL, and it reports each as a separate result with the underlying data. The output is a Certificate of Analysis tied to that one lot.

What happens when a batch does not pass

A testing program is only meaningful if a failing result actually stops a batch. When a lot does not meet its specification — purity below threshold, an identity mismatch, or an out-of-range endotoxin result — it should be held rather than released, regardless of how much material is involved.

Testing every batch, rather than one representative sample used to vouch for many, is what makes the COA on your vial describe your vial. Batch-level, independent testing is slower and more expensive than a single generic report, and that cost is exactly what buys the confidence.

A testing program only means something if a failing result can stop a batch.