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 C—Blood Grouping Reagent (§660.20 to §660.28) > 660.26—Specificity tests and avidity tests.