Why does CAS 3520-42-1 appear in more than one EU cosmetic annex?

A substance identified by CAS 3520-42-1 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts — for example, restricted under Annex III with specific conditions, while also appearing in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

How do I check if my formula contains a substance with CAS 3520-42-1?

Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 3520-42-1 to screen it directly, then review every linked annex record and supplier document.

CAS 2 records

CAS 3520-42-1

Q: How do I use CAS 3520-42-1 for compliance screening?

Cross-reference CAS 3520-42-1 against your raw material specification sheets and CoA documents. When it appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met. All annex entries sharing this CAS number are listed on this page.

CAS 3520-42-1 matches 2 EU annex records across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 3520-42-1

CAS 3520-42-1PubChem CID 9916275

Acid Red 52

Lissamine rhodamine is an organic sodium salt having 4-[3,6-bis(diethylamino)xanthenium-9-yl]benzene-1,3-disulfonate as the counterion. It has a role as a fluorescent probe, a fluorochrome and a histological dye. It contains a lissamine rhodamine anion. — ChEBI

IUPAC name: sodium 4-[3-(diethylamino)-6-diethylazaniumylidenexanthen-9-yl]benzene-1,3-disulfonate

Molecular formula: C27H29N2NaO7S2
Molecular weight: 580.7 g/mol
Exact mass: 580.13138790 Da
Topological polar surface area: 147.0 Å²
Hydrogen-bond donors: 0
Hydrogen-bond acceptors: 8
Covalent units: 2
Defined stereocentres: 0

Also known as

C.I. Acid Red 52Acid Rhodamine BLissamine RhodamineKiton Rhodamine BXylene Red BAmido Rhodamine BAcid Red XBFood Red 106

16 more reported names

Fenazo Pink XXBSolar Rhodamine BAmacid Rhodamine BErio Acid Red XBErio Acid Red XBCRed No. 106Acid Leather Red KBAizen Food Red No. 106Pontacyl Brilliant PinkBrilliant Acid Rhodamine BCI 45100Red 106Brilliant Superlan Rhodamine BBrilliant Superlan Rhodamine 2B821LWZ3R6RVIBRACOLOR RED ARE52

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:52101
ChEMBL:CHEMBL1306565
EPA DTXSID:DTXSID7021235

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 3520-42-1

2 total

Annex

III

Entry

193

ACID RED 52

Hydrogen 3,6-bis(diethylamino)-9-(2,4-disulphonatophenyl)xanthylium, sodium salt; CI 45100 (see note 17)

a) To be printed on the label: The mixing ratio. “ Hair colourants can cause severe allergic reactions. Read and follow instructions. This product is not intended for use on persons under the age of 16. Temporary ‘black…

222-529-8

Max concentration

Annex

Entry

CI 45100/ ACID RED 52

Hydrogen 3,6-bis(diethylamino)-9-(2,4-disulphonatophenyl)xanthylium, sodium salt

222-529-8

Max concentration

How CAS 3520-42-1 is used on this site

CAS 3520-42-1 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 2 EU annex records share this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 3520-42-1 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.

Frequently asked questions

A substance identified by CAS 3520-42-1 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

Cross-reference the CAS number against your raw material specification sheets and CoA documents. When a CAS appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met in your formulation. All annex entries sharing this CAS number are listed above.

A CAS number is assigned by the Chemical Abstracts Service (USA) and is globally recognised. An EC number is a European Commission identifier from inventories such as EINECS, ELINCS or the NLP list. Both identifiers may appear in EU cosmetic annex entries. Some substances have both, some have only one, and some older entries may have neither.

The INCI Checker accepts ingredient names, CAS numbers and EC numbers. Check this CAS number directly, then verify the result against supplier specification sheets and every linked annex condition.

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