Code of Federal Regulations Title 21. Food and Drugs § 21.73.1329 Guanine

(a) Identity.

(b) Specifications. The color additive guanine shall conform to the following specifications and shall be free from impurities other than those named to the extent that such other impurities may be avoided by good manufacturing practice:

Guanine, not less than 75 percent.

Hypoxanthine, not more than 25 percent.

Ash (ignition at 800 °C), not more than 2 percent.

Lead (as Pb), not more than 20 parts per million.

Arsenic (as As), not more than 3 parts per million.

Assay, not less than 96 percent total purines.

Mercury (as Hg), not more than 1 part per million.

(c) Uses and restrictions. Guanine is safe for use in coloring externally applied drugs, including those intended for use in the area of the eye, in amounts consistent with good manufacturing practice.

(d) Labeling. The color additive and any mixture prepared therefrom intended solely or in part for coloring purposes shall bear, in addition to any information required by law, labeling in accordance with § 70.25 of this chapter.

(e) Exemption from certification. Certification of this color additive is not necessary for the protection of the public health, and therefore batches thereof are exempt from certification pursuant to section 721(c) of the act.