A Reference Hepatitis B Surface Antigen Panel shall be obtained from the Center for Biologics Evaluation and Research (HFM-407) (see mailing addresses in Sec. 600.2 of this chapter) and shall be used for determining the potency and specificity of Antibody to Hepatitis B Surface Antigen. [40 FR 29711, July 15, 1975, as amended at 49 FR 23834, June 8, 1984; 55 FR 11013, Mar. 26, 1990; 70 FR 14985, Mar. 24, 2005]