§74.102 FD&C Blue No. 2.
（a） Identity. （1） The color additive FD&C Blue No. 2 is principally the disodium salt of 2-（1,3-dihydro-3-oxo-5-sulfo-2H -indol-2-ylidene）-2,3-dihydro-3-oxo-1H -indole-5-sulfonic acid （CAS Reg. No. 860-22-0） with smaller amounts of the disodium salt of 2-（1,3-dihydro-3-oxo-7-sulfo-2H -indol-2-ylidene）-2,3-dihydro-3-oxo-1H -indole-5-sulfonic acid （CAS Reg. No. 54947-75-0） and the sodium salt of 2-（1,3-dihydro-3-oxo-2H -indol-2-ylidene）-2,3-dihydro-3-oxo-1H -indole-5-sulfonic acid （CAS Reg. No. 605-18-5）. Additionally, FD&C Blue No. 2 is obtained by heating indigo （or indigo paste） in the presence of sulfuric acid. The color additive is isolated and subjected to purification procedures. The indigo （or indigo paste） used above is manufactured by the fusion of N -phenylglycine （prepared from aniline and formaldehyde） in a molten mixture of sodamide and sodium and potassium hydroxides under ammonia pressure. The indigo is isolated and subjected to purification procedures prior to sulfonation.
（2） Color additive mixtures for food use （including dietary supplements） made with FD&C Blue No. 2 may contain only those diluents that are suitable and that are listed in part 73 of this chapter as safe for use in color additive mixtures for coloring foods.
（b） Specifications. The color additive FD&C Blue No. 2 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 current good manufacturing practice:
Sum of volatile matter at 135 °C （275 °F） and chlorides and sulfates （calculated as sodium salts）, not more than 15 percent.
Water insoluble matter, not more than 0.4 percent.
Isatin-5-sulfonic acid, not more than 0.4 percent.
5-Sulfoanthranilic acid, not more than 0.2 percent.
Disodium salt of 2-（1,3-dihydro-3-oxo-7-sulfo-2H-indol-2-ylidene）-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid, not more than 18 percent.
Sodium salt of 2-（1,3-dihydro-3-oxo-2H-indol-2-ylidene）-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid, not more than 2 percent.
Lead （as Pb）, not more than 10 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 85 percent.
（c） Uses and restrictions. The color additive FD&C Blue No. 2 may be safely used for coloring foods （including dietary supplements） generally in amounts consistent with current good manufacturing practice except that it may not be used to color foods for which standards of identity have been promulgated under section 401 of the Federal Food, Drug, and Cosmetic Act unless added color is authorized by such standards.
（d） Labeling. The label of the color additive and any mixtures prepared therefrom intended solely or in part for coloring purposes shall conform to the requirements of § 70.25 of this chapter.
（e） Certification. All batches of FD&C Blue No. 2 shall be certified in accordance with regulations in part 80 of this chapter.
[48 FR 5260, Feb. 4, 1983]
