Why Lot Numbers Matter
A lot number links a physical container to the records that describe it. Without one, documentation cannot be checked against the container.
4 min read
What a lot is
A lot is a quantity of material produced under one set of conditions and treated as a single unit for record-keeping. A lot number is the identifier assigned to it. Batch numbering is sometimes used alongside lot numbering to describe a related grouping, such as a production run from which several lots were drawn, and the two are recorded separately when both apply.
The identifier distinguishes one quantity of material from every other quantity of the same compound.
Why results cannot be generalised
Analytical testing is performed on a sample drawn from a particular lot. The results describe that sample and, by extension, the lot it came from, but no other material.
Two lots of the same compound are separate materials. They may have been made at different times, from different starting materials, under conditions that differed in ways that affect the result. Applying one lot's analytical result to another is an inference the measurement does not support.
So a purity figure presented as a property of a compound is a weaker statement than the same figure attached to an identified lot, because only the lot-level figure can be checked.
Traceability in both directions
A working lot number lets information travel both ways. Starting from a container, the number printed on the label leads to the records describing that material. Starting from a record, the number leads back to the material the record describes.
Documentation needs both directions to work as verification. A certificate that cannot be tied to the container in front of you establishes nothing about that container.
What to look for
Check that the lot number on the container matches the lot number on the documentation exactly. You should be able to retrieve documentation by lot number as well as by compound. Where a lot has no published documentation, the record should say so, with no value carried over from elsewhere.
A missing record is itself information: it shows that no result has been published for that lot. A plausible-looking value in its place would make the documentation useless for verification.
This article is general reference material describing methods and records. It does not describe any particular material and is not medical advice.
