Section 660.21 - Processing(a)Processing method.(1) The processing method shall be one that has been shown to yield consistently a specific, potent final product, free of properties that would affect adversely the intended use of the product throughout its dating period. Stability testing shall be performed on an adequate number of representative samples of each group of products manufactured in the same fashion.(2) Only that material that has been fully processed, thoroughly mixed in a single vessel, and filtered shall constitute a lot.(3) A lot may be subdivided into sublots. If lots are to be subdivided, the manufacturer shall include this information in the biologics license application. The manufacturer shall describe the test specifications to verify that each sublot is identical to other sublots of the lot.(4) Each lot of Blood Grouping Reagent shall be identified by a lot number. Each sublot shall be identified by that lot number to which a distinctive prefix or suffix shall be added. Final container and package labels shall bear the lot number and all distinctive prefixes and suffixes that have been applied to identify the sublot from which filling was accomplished.(b)Color coding of reagents. Blood Grouping Reagents may be colored provided the added colorant does not adversely affect the safety, purity, or potency of the product and the colorant is approved by the Director, Center for Biologics Evaluation and Research.(c)Final containers and dropper assemblies. Final containers and dropper pipettes shall be colorless and sufficiently transparent to permit observation of the contents to detect particulate matter or increased turbidity during use.(d)Volume of final product. Each manufacturer shall identify the possible final container volumes in the biologics license application.(e)Date of manufacture. The date of manufacture shall be the date the manufacturer begins the last entire group of potency tests.53 FR 12764, Apr. 19, 1988, as amended at 64 FR 56454, Oct. 20, 1999; 65 FR 77499 , Dec. 12, 2000; 67 FR 9587 , Mar. 4, 2002; 70 FR 14985 , Mar. 24, 2005