CFR > Title 21 - Food and Drugs > CHAPTER I—FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES > SUBCHAPTER F—BIOLOGICS (parts 600 to 680) > PART 660—ADDITIONAL STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS > SUBPART A—Antibody to Hepatitis B Surface Antigen (§660.1 to §660.6)