(a) For each test or control article that is mixed with a carrier, tests by appropriate analytical methods shall be conducted:
(1) To determine the uniformity of the mixture and to determine, periodically, the concentration of the test or control article in the mixture.
(2) To determine the stability of the test and control articles in the mixture as required by the conditions of the study either:
(i) Before study initiation, or
(ii) Concomitantly according to written standard operating procedures which provide for periodic analysis of the test and control articles in the mixture.
(c) Where any of the components of the test or control article carrier mixture has an expiration date, that date shall be clearly shown on the container. If more than one component has an expiration date, the earliest date shall be shown.