FD&C Blue No. 2
FD&C Blue No. 2 (indigotine) is a synthetic, water-soluble royal blue dye made by sulfonating synthetic indigo with sulfuric acid, then purifying and isolating the disodium salt. Every batch must be certified by FDA before sale. It is less stable to light than FD&C Blue No. 1, and is sold as straight dye powder, liquid solutions and aluminum lakes, with lakes common in tablet coatings and confectionery.
Suppliers sell different products under the same name. Specify the one you need.
Spray-dried or granular FD&C Blue No. 2 with a stated total (pure) dye content, dissolved in water or syrup before use.
Agglomerated grades that make less airborne dust in the weigh room and dissolve without clumping.
Ready-to-dose water or glycol solutions at a stated dye percentage, often preserved, for beverage and syrup plants.
The dye laked onto alumina so it disperses rather than dissolves, used in tablet coatings, fat-based coatings and dry mixes.
Pre-mixed shades combining several certified colors, each of which must come from a certified batch.
Compare each result with your own specification when the lot arrives.
Store in the original sealed containers in a cool, dry place away from light; powders are hygroscopic and cake in humid rooms, and dust should be controlled because small amounts stain other products. Shelf life is set by the supplier, and certified colors are generally retested for total color and appearance once past the supplier retest date. Keep each container's FDA certification lot number with the stock so it can be traced into finished batches.
Record the FDA certification lot number and the actual total color of each lot of FD&C Blue No. 2, and adjust dosing when the dye content differs from the previous lot. Compare shade against a retained standard in the finished product, since small subsidiary-color differences can shift hue.
Facts from regulators and standards bodies, each linked to its source.
21 CFR 74.102 lists FD&C Blue No. 2 for coloring foods, including dietary supplements, generally at current good manufacturing practice levels.
Source: ecfr.gov (opens in a new tab)21 CFR 74.102 describes FD&C Blue No. 2 as obtained by heating indigo in the presence of sulfuric acid, and requires every batch to be FDA-certified.
Source: ecfr.gov (opens in a new tab)FDA's April 22, 2025 news release lists FD&C Blue No. 2 among six synthetic dyes FDA is working with industry to eliminate from the food supply by the end of the following year.
Source: fda.gov (opens in a new tab)Health Canada's List of Permitted Colouring Agents includes indigotine (item I.1).
Source: canada.ca (opens in a new tab)This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Manufacturers and distributors whose own websites say they sell it.
Manufacturer · St. Louis, MO
North American food color business of Sensient Technologies, making certified FD&C dyes and lakes alongside natural colors from sources such as beet juice, carmine, annatto, spirulina and butterfly pea flower.
Suppliers are in alphabetical order and none pays to appear. Each claim is checked against the supplier’s own website on the date shown. Ask for the specification sheet and a recent COA before you order, and confirm details with the supplier.
Common forms include straight color powder, granular or dust-reduced, liquid solution, aluminum lake and blends. Ask each supplier for the specification sheet of the exact grade they quote.
Expect fDA certification lot number, total color (pure dye), volatile matter, chlorides and sulfates, subsidiary colors and intermediates, heavy metals and water-insoluble matter, each with its method, specification and result for that lot.
Store in the original sealed containers in a cool, dry place away from light; powders are hygroscopic and cake in humid rooms, and dust should be controlled because small amounts stain other products. Shelf life is set by the supplier, and certified colors are generally retested for total color and appearance once past the supplier retest date. Keep each container's FDA certification lot number with the stock so it can be traced into finished batches.
21 CFR 74.102 lists FD&C Blue No. 2 for coloring foods, including dietary supplements, generally at current good manufacturing practice levels. 21 CFR 74.102 describes FD&C Blue No. 2 as obtained by heating indigo in the presence of sulfuric acid, and requires every batch to be FDA-certified. FDA's April 22, 2025 news release lists FD&C Blue No. 2 among six synthetic dyes FDA is working with industry to eliminate from the food supply by the end of the following year. Health Canada's List of Permitted Colouring Agents includes indigotine (item I.1).
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