21 CFR §660.51

1. (a)Processing method.
   1. (1)The processing method shall be one that has been shown to yield consistently a specific, potent final product, free of properties that would adversely affect the product for its intended use throughout its dating period.
   2. (2)Anti-IgG, -C3d (polyspecific) reagents and anti-IgG products may be colored green.
   3. (3)Only that material which has been fully processed, thoroughly mixed in a single vessel, and filtered shall constitute a lot. Each lot shall be identified by a lot number.
   4. (4)A lot may be subdivided into sublots which shall be identified by the lot number to which has been added a distinctive prefix or suffix. If lots are to be subdivided, the manufacturer shall include this information in the license application . The manufacturer shall describe the test specifications to verify that each sublot is identical to other sublots of the lot.
2. (b)Final containers and dropper assemblies.
   1. (1)Final containers and dropper assemblies shall be clean.
   2. (2)Final containers and dropper pipettes shall be colorless and sufficiently transparent to permit observation of the contents for presence of particulate matter or increased turbidity.
3. (c)Date of manufacture. The date of manufacture shall be the date the manufacturer begins the last entire group of potency tests.