Batch number (revision 5)

A batch number — equivalently a lot number — is the identifier assigned to a quantity of material produced under uniform conditions. It appears on the container label and on the certificate of analysis, and it is the only thing connecting the two.^[1]

The number itself carries no information about quality. Its function is referential: it allows a determination recorded against a lot to be applied to a container, and it allows a container to be traced to production records. A batch number with no records behind it is a string of characters.^[2]

What can be observed about a batch number is whether it is present, whether it is consistent across the vial, the certificate and the shipping paperwork, and whether the supplier can retrieve records against it after the fact. See Lot traceability.

Numbers may be assigned at several stages, and the stage determines what the number identifies. A number assigned at synthesis identifies a production campaign; at purification, a pool; at fill, a filling run; at packing, a shipment. These are not equivalent, and the same physical material can carry different identifiers under different schemes.^[3]

Formats vary and no convention is universal. Common patterns encode a date, a product code and a sequence; others are opaque serial numbers. An encoded date is convenient but is not verification: a date embedded in an identifier is an assertion like any other field on a label.

The practical consequence is that comparing batch numbers between suppliers, or inferring production volume from sequence numbers, is unsound. Sequence numbers may be per-product, per-year, per-line or arbitrary.