Why Lot Numbers Matter
A lot number is the link between a physical container and the records that describe it. Without it, documentation is unverifiable.
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 exists to make one specific quantity of material distinguishable 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. They describe nothing else.
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.
This is why a purity figure presented as a property of a compound is a weaker statement than the same figure attached to an identified lot. The first cannot be checked. The second can.
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.
Both directions are necessary for documentation to function as verification rather than decoration. A certificate that cannot be tied to the container in front of you establishes nothing about that container.
What to look for
The lot number on the container should match the lot number on the documentation exactly. Documentation should be retrievable by lot number rather than only by compound. Where a lot has no published documentation, that should be stated plainly rather than filled with a value carried over from elsewhere.
The absence of a record is information. Substituting a plausible-looking value for a missing one destroys the only thing documentation is for.
This article is general reference material describing methods and records. It does not describe any particular material, contains no dosing, reconstitution, or administration information, and is not medical advice.