CFR › Title 21 › Part 660 › §660.5421 CFR §660.54Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkThe following tests shall be performed using test procedures approved by the Director, Center for Biologics Evaluation and Research:(a)Potency tests for determining anti-IgG and anti-complement activity.(b)Specificity tests, tests for heterospecific antibodies, and additional tests for nonspecific properties.