Blue 1
Synonyms: Brilliant Blue FCF, FD&C Blue No. 1, CI 42090, E133 (food use); insoluble variant: Blue 1 Lake (Aluminum Lake of CI 42090)
Functions (food/cosmetic/pharma): water-soluble colorant (bright blue), tonalizer, tracer; as a lake, an insoluble pigment for anhydrous/lipid systems

Definition
Blue 1 is a synthetic triarylmethane-type (commonly grouped with azo/triphenylmethane dyes) colorant supplied as the sodium salt, highly water-soluble and used to deliver an intense blue hue to beverages, confections, supplements, pharmaceuticals, and aqueous cosmetics. Blue 1 Lake is the corresponding aluminum lake pigment for oil/anhydrous applications.

Calories (energy value)
0 kcal per 100 g (synthetic colorant; no metabolizable energy).

Composition and structure

• Colorant: Brilliant Blue FCF, sodium salt (CI 42090).

• Purity: high, with strict heavy-metal limits (Pb, As, Cd, Hg) and tight controls on subsidiary colors.

• Physical form: intense blue powder/granules; shade can shift slightly with pH/ionic strength.

Physicochemical properties (indicative)

• Solubility: freely soluble in water; insoluble in oils.

• λmax (UV–Vis): typically ~628–635 nm in water at neutral pH.

• pH tolerance: stable across ~2–10; fading occurs with strong oxidants or reducing agents.

• Light/heat stability: good in aqueous systems; complexation with metal ions may affect tone (use chelators if needed).

• Compatibility: excellent in beverages, gels, syrups, shampoos, body washes; use Blue 1 Lake for anhydrous or oil phases.

Manufacturing overview (soluble form)

1. Synthesis of the chromophore from aromatic intermediates via controlled coupling/sulfonation steps.

2. Neutralization/salt formation (sodium salt).

3. Purification (filtration, washing, deionization) to minimize salts, by-products, and metals.

4. Drying and standardization (moisture, tinctorial strength); optional granulation for dust control/dosing.
   (For Blue 1 Lake: co-precipitate the dye onto aluminum hydroxide → wash → dry → micronize/classify.)

Advantages and limitations

• Advantages (soluble): pure, brilliant blue, easy aqueous dosing, broad pH stability.

• Limitations: bleeding/migration in moist matrices; not suitable for lipid systems (use the Lake). Sensitive to strong redox conditions.

Application areas

• Food (E133): beverages, ice pops, icings, confectionery, jellies, decorations, and the aqueous phase of baked goods.

• Cosmetics

It was admitted to the list of authorised colourants in cosmetic products by Directive 76/768/ECC.

It is used as a direct colouring agent in hair colouring products. Its concentration in the finished cosmetic product must not exceed 0.5%. It is also subject to cosmetic restrictions IV/63 and III/190.

• Food

In the food industry, it is included in the list of colouring food additives under the number E133. In 1970 FAO/WHO Expert Committee on Food Additives established an acceptable daily intake (ADI) of 0-12.5 mg/kg body weight. The Scientific Committee on Food of the EEC recommended an ADI of 10 mg/kg body weight in 1983.

• Pharmaceuticals: coated tablets/capsules, syrups; also used as a visual tracer. 

Formulation guidelines

• Pre-dissolve in water or glycerin; avoid clumping.

• Employ chelators (e.g., EDTA, citrate) to mitigate metal-ion effects (haze/tone shifts).

• Maintain pH 2–9 for optimum stability; avoid strong oxidants/reductants.

• In high-electrolyte systems, check for haze and adjust ionic strength/chelators.

• For anhydrous/oily products, pre-disperse Blue 1 Lake in a low-viscosity ester/oil and apply sufficient shear (three-roll/ball mill or high-shear mixer).

Safety and regulatory

• EU (Cosmetics, Reg. 1223/2009): CI 42090 listed in Annex IV (approved colorants) with purity specs; generally allowed across categories within spec.

• EU (Food): E133 authorized with category-specific limits and an ADI; observe local regulations.

• USA (FDA): FD&C Blue No. 1 and its Aluminum Lakes are certifiable color additives; batch certification required. Some drug/cosmetic uses require label declaration.

• Hypersensitivity: overall low incidence; rare reactions may occur in predisposed individuals.

• Heavy metals: comply strictly with limits for Pb, As, Cd, Hg (and antimony for lakes).

Stability, storage, quality

• Store cool, dry, and light-protected in sealed, opaque containers.

• Shelf life: typically 36–60 months when properly stored.

• QC controls: UV–Vis identity/strength (λmax, absorbance), tinctorial strength, solution pH, insolubles, trace metals.

Troubleshooting

• Fading/discoloration: presence of oxidants/reductants or extreme pH—adjust formulation, add suitable antioxidants, and buffer pH.

• Haze/precipitation in hard-water beverages: introduce chelators (EDTA/citrate) or reduce ionic load.

• Migration in icings/creams: consider partial replacement with Blue 1 Lake in fat phases.

Conclusion
Blue 1 (CI 42090 / E133) is a workhorse water-soluble blue for aqueous foods, cosmetics, and pharmaceuticals, offering bright color and robust pH stability. The Lake form extends use to oily/anhydrous systems. With appropriate purity control, metal chelation, pH management, and Lake co-use where needed, it delivers clean, reproducible, and compliant color performance.

CI 42090 Acid Blue 9 studies

• 
  Molecular Formula: C₃₇H₄₂N₄O₉S₃
• Molecular Weight: 782.942 g/mol
• UNII: 86R7G3C26F
• CAS: 2650-18-2  1334-07-2  29519-65-1  37307-55-4  37307-56-5  37307-78-1  51609-24-6  55819-29-9  86924-52-9  99149-43-6  511534-54-6
• EC Number: 220-168-0  223-339-8
• PubChem Substance ID 329769043
• MDL number MFCD00012141
• Colour Index Number 42090

Synonyms:

• Erioglaucine A
• Acid Blue 9
• C.I. Acid Blue 9
• Erioglaucine
• E133
• Kiton Pure Blue L
• Pro-Jet Blue OAM
• Erioglaucine (VAN)
• Daiwa Blue 109H
• Japan Blue 205
• Eriosky Blue
• Amacid Blue FG Conc
• Duasyn Acid Blue AE
• Orient Water Blue 9
• Schultz No. 770
• Caswell No. 007A
• CI Direct Brown 78
• Edicol Supra Blue E6
• Vitasyn Blue AE 85
• AF Blue No. 1
• Alphazurine (indicator)
• Xylene Blue VSG
• Acid Sky Blue A
• Alphazurine FG
• Erioglaucine E
• Alphazurine FGND
• Neptune Blue WF
• Fenazo Blue XR
• Patent Blue AE
• Calcocid Blue EG
• Kiton Blue AR
• Neptune Blue BRA
• Patent Blue 2Y
• Tortrazine C extra
• Calcocid Blue 2G
• Water Blue 9
• Bucacid Azure Blue
• Hidacid Azure Blue
• Acid Blue AE-SF
• Bleu Brilliant FCF
• Brilliant Blue Lake
• Aizen Brilliant Blue FCF
• Maple Brilliant Blue FCF
• C.I. Direct Brown 78
• Triantine Light Brown 3RN
• Acilan Turquoise Blue AE
• Peacock Blue X-1756
• CI ACID BLUE 9
• CI Acid Blue 9, diammonium salt
• D and C Blue No. 4
• Duasyn Acid Blue AE-SF
• A.F. Blue No. 1
• C.I. Acid Blue 9, diammonium salt
• Dolkwal Brilliant Blue