Colouring agent CI 26105 (Solvent Red 24)
Colouring agent CI 26105 (Solvent Red 24) is listed in Annex II as a prohibited substance for cosmetic products placed on the EU market.
Chemical identity and properties

Sudan IV
Sudan IV is a bis(azo) compound that is 2-naphthol substituted at position 1 by a {2-methyl-4-[(2-methylphenyl)diazenyl]phenyl}diazenyl group. A fat-soluble dye predominantly used for demonstrating triglycerides in frozen sections, but which may also stain some protein bound lipids in paraffin sections. It has a role as a carcinogenic agent, a fluorochrome and a histological dye. It is a member of azobenzenes, a member of naphthols and a bis(azo) compound. It is functionally related to a 2-naphthol. — ChEBI
- IUPAC name
- 1-[[2-methyl-4-[(2-methylphenyl)diazenyl]phenyl]diazenyl]naphthalen-2-ol
- Molecular formula
- C24H20N4O
- Molecular weight
- 380.4 g/mol
- Exact mass
- 380.16371127 Da
- XLogP3
- 7.1
- Topological polar surface area
- 69.7 Ų
- Hydrogen-bond donors
- 1
- Hydrogen-bond acceptors
- 5
- Covalent units
- 1
- Defined stereocentres
- 0
Also known as
16 more reported names
External database identifiers
- ChEBI:CHEBI:88014
- ChEMBL:CHEMBL1707454
- ChEMBL:CHEMBL4303605
- EPA DTXSID:DTXSID8041743
- PubMed:9842
Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.
Record details
Chemical name
Colouring agent CI 26105 (Solvent Red 24)
Chemical / IUPAC name
1-(2-Methyl-4-(2-methylphenylazo)phenylazo)-2-naphthol
Regulatory information
Identified ingredients
Key data
Inventory links for Colouring agent CI 26105 (Solvent Red 24)
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What Annex II means for Colouring agent CI 26105 (Solvent Red 24)
Colouring agent CI 26105 (Solvent Red 24) is listed as a prohibited substance under Annex II of EU Cosmetics Regulation 1223/2009 and must not be intentionally added. Article 17 separately addresses unintended small quantities that are technically unavoidable under good manufacturing practice and compatible with the Article 3 safety requirement.
Formulators must screen their ingredients and raw materials to ensure none contain this substance. Suppliers should provide documentation confirming absence when requested.
This record is linked to 1 CosIng inventory ingredient for name and identifier cross-reference. The page also surfaces 12 related annex records with overlapping identifiers, annex logic or naming patterns.
Compliance checklist
- Verify this substance is absent from all raw materials and finished formulations.
- Request absence confirmation or CoA from raw material suppliers.
- Document the screening result in the Product Information File (PIF).
Frequently asked questions
Source note for Annex II record Colouring agent CI 26105 (Solvent Red 24)
This page summarizes one Annex II record for Colouring agent CI 26105 (Solvent Red 24) from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.
Use this record page to review Annex II conditions for Colouring agent CI 26105 (Solvent Red 24), but confirm any final regulatory decision against the current official annex wording and source files.
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