Does TFC issue lot-specific documentation, or a batch certificate?

The lot number on the vial matches the certificate, which at least rules out the easy problem.

The figures are clear enough; the question is what they mean and what they do not.

I can supply the numbers if the specifics change the answer.

What would I need in addition before this supported a decision?

Worth being precise here: thermal history during shipping is different for every vial, so a lot that experienced thermal abuse may have internal variation even if it was originally homogeneous.

The sample size determination requires choosing a confidence level and an acceptable error rate, and the smaller the error rate you want, the larger your sample must be.

In practice, if the entire lot failed qualification, a retest on a different vial is sometimes done, but reporting a retest result under the same lot number is misleading.

Lyophilised peptide homogeneity studies show that vial-to-vial variation is usually small but occasionally large, depending on the distribution in the freeze-dryer.

The practical summary: a lot number without a sampling statement is a lot number without meaning.

Most suppliers test one vial per lot and report the result as lot homogeneity, which is sampling one item from one lot and extrapolating wildly.

For a quantitative result like content, the acceptable range determines how many vials you need to test to establish the lot complies.

Published segregation failures show that even modern automated processes sometimes produce lots with measurable vial-to-vial variation.

If testing multiple vials, state how many you tested and why you chose those vials.

edited 13 Aug 2025 by kwn_analytical — updated for the 2026 guidance change

Specifically, the failure mode here is publishing a result that applies to the tested vial alone while implying it applies to the entire lot.

Testing a vial that has been open in the lab for three months is testing aged material, not the fresh lot, and the result should be explicitly noted as a retest.

Sampling plans for pharmaceutical manufacturing are defined in ISO 2859 and ANSI Z1.4, and they are based on statistical sampling theory.

I would treat a "complies with" statement without sampling details as a claim rather than as evidence.

If you only pay for one test, pay for quantified content. Purity is the number everyone quotes and content is the number that changes what you do.

edited 15 May 2025 by thabo_maseko — tightened the wording; no substantive change