21 CFR § 74.1104 - D&c Blue No. 4.

---
identifier: "/us/cfr/t21/s74.1104"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 74.1104 - D&C Blue No. 4."
title_number: 21
title_name: "Food and Drugs"
section_number: "74.1104"
section_name: "D&C Blue No. 4."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "A"
subchapter_name: "GENERAL"
part_number: "74"
part_name: "LISTING OF COLOR ADDITIVES SUBJECT TO CERTIFICATION"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 321, 341, 342, 343, 348, 351, 352, 355, 361, 362, 371, 379e."
regulatory_source: "42 FR 15654, Mar. 22, 1977, unless otherwise noted."
cfr_part: "74"
---


# 74.1104 D&C Blue No. 4.

(a) *Identity.* (1) The color additive D&C Blue No. 4 is principally the diammonium salt of ethyl[4-[*p*[ethyl(*m-* sulfobenzyl)ami-no]-α-(*o-* sulfophenyl)benzylidene]-2,5-cyclo-hexadien-1-ylidene] (*m-* sulfobenzyl) ammonium hydroxide inner salt with smaller amounts of the isomeric diammonium salts of ethyl [4-[*p-*[ethyl(*p-* sulfobenzyl) amino]-α-(*o-* sulfophenyl) benzylidene]-2,5-cyclohexadien - 1-ylidene](*p-* sulfobenzyl) ammonium hydroxide inner salt and ethyl[4-[*p-*[ethyl (*o-* sulfobenzyl)amino]-α-(*o-* sulfophenyl) benzylidene]-2,5-cyclohexadien-1-ylidene] (*o-* sulfobenzyl) ammonium hydroxide inner salt.

(2) Color additive mixtures for use in externally applied drugs made with D&C Blue No. 4 may contain only those diluents that are suitable and that are listed in part 73 of this chapter for use in color additive mixtures for coloring externally applied drugs.

(b) *Specifications.* D&C Blue 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 15 percent.

Water-insoluble matter, not more than 0.2 percent.

Leuco base, not more than 5 percent.

Sum of *o-, m*, and *p-* sulfobenzaldehydes, ammonium salt, not more than 1.5 percent.

N-ethyl, N-(*m-* sulfobenzyl) sulfanilic acid ammonium salt, not more than 0.3 percent.

Subsidiary colors, not more than 6 percent.

Chromium (as Cr), not more than 50 parts per million.

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 85 percent.

(c) *Uses and restrictions.* D&C Blue No. 4 may be safely used in externally applied drugs in amounts consistent with good manufacturing practice.

(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 D&C Blue No. 4 shall be certified in accordance with regulations in part 80 of this chapter.