The material selection platform
Cosmetics Ingredients
The material selection platform
Cosmetics Ingredients

CI 42090

CAS Number 3844-45-9
Chem/IUPAC Name: Dihydrogen (ethyl)[4-[4-[ethyl(3-sulphonatobenzyl)]amino]-2'-sulphonatobenzhydrylidene]cyclohexa-2,5-dien-1-ylidene](3-sulphonatobenzyl)ammonium, disodium salt, Brilliant Blue FCF (Blue 1)
EINECS/ELINCS No: 223-339-8
COSING REF No: 32756
CI 42090
CI 42090 is a synthetic compound that gives a brilliant blue color to products like shampoos, hair colors, and soaps. It is basically a colorant that is widely prevalent in the cosmetic industry. It is also known by other names such as Blue 1 CI 42090 or CI 42090 Blue 1. It comes in powder form and is highly concentrated when used as a primary color. That said, it can also be mixed with other colorants to produce a wide range of hues and shades. The chemical formula of CI 42090 is C37H37N2O9S3.

What is CI 42090 used for?

The primary objective of CI 42090 is to add brilliant blue color to cosmetic, skin care, and hair care products. It can further be mixed with tartrazine to result in beautiful shades of green. It is used in a range of products like toothpaste, nail paints, shampoos, and eyeliners.


The cosmetic colorant CI 42090 is made synthetically from petroleum. It is made by the condensation of 2-formylbenzenesulfonic acid. It is further oxidized to produce the smurf blue powder known as CI 42090. It is classified as triarylmethane dye.

What does CI 42090 do in a formulation?

  • Cosmetic colorant

Safety profile

CI 42090 has been deemed safe for use on skin and hair, even though it is synthetic. It does not pose any risk unless it is consumed. Therefore, CI 42090 should not be used in any breathable products such as perfumes. Apart from this, it can also cause skin irritation and redness among people allergic to dyes. A patch test of products containing this ingredient is recommended. CI 42090 is also vegan and halal as it is free of animal products.

Technical profile

Property Values
Boiling Point 283°C
Solubility Soluble in water

Commercial Selection : Grades containing solely CI 42090

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