21 C.F.R. § 74.1254
(a) Identity.
(b) Specifications. D&C Orange No. 4 shall conform to the following specifications and shall be free from impurities other than those named to the extent that such impurities may be avoided by good manufacturing practice.
Sum of volatile matter (at 135 °C) and chlorides and sulfates (calculated as sodium salts), not more than 13 percent. Water-insoluble matter, not more than 0.2 percent. 2-Naphthol, not more than 0.4 percent. Sulfanilic acid, sodium salt, not more than 0.2 percent. Subsidiary colors, not more than 3 percent. 4,4′-(Diazoamino)-dibenzenesulfonic acid, not more than 0.1 percent. Lead (as Pb), not more than 20 parts per million. Arsenic (as As), not more than 3 parts per million. Mercury (as Hg), not more than 1 part per million. Total color, not less than 87 percent.
[42 FR 52396, Sept. 30, 1977, as amended at 43 FR 14642, Apr. 7, 1978; 46 FR 8461, Jan. 27, 1981]