Why does CAS 73-40-5 appear in more than one EU cosmetic annex?

A substance identified by CAS 73-40-5 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 73-40-5?

Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 73-40-5 to screen it directly, then review every linked annex record and supplier document.

CAS 1 record

CAS 73-40-5

Q: How do I use CAS 73-40-5 for compliance screening?

Cross-reference CAS 73-40-5 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 73-40-5 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 73-40-5

CAS 73-40-5PubChem CID 135398634

Guanine

Guanine is a 2-aminopurine carrying a 6-oxo substituent. It has a role as a mouse metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a human metabolite and an algal metabolite. It is a member of 2-aminopurines, an oxopurine and a purine nucleobase. It derives from a hydride of a 9H-purine. — ChEBI

IUPAC name: 2-amino-1,7-dihydropurin-6-one

Molecular formula: C5H5N5O
Molecular weight: 151.13 g/mol
Exact mass: 151.04940980 Da
XLogP3: -1.1
Topological polar surface area: 96.2 Å²
Hydrogen-bond donors: 3
Hydrogen-bond acceptors: 3
Covalent units: 1
Defined stereocentres: 0

Also known as

2-Amino-6-hydroxypurine2-AminohypoxanthineGuaninMearlmaidGuanine enolPearl essenceStella PolarisDew Pearl

16 more reported names

NaturonNatural white 1Natural pearl essence6H-Purin-6-one, 2-amino-1,7-dihydro-2-Amino-1,7-dihydro-6H-purin-6-oneCI Natural white 1C.I. Natural White 1Hypoxanthine, 2-amino-6-Hydroxy-2-aminopurineCI 751702-amino-3,7-dihydropurin-6-oneC.I. 75170CHEBI:162355Z93L87A1RC.i. no. 75170 (guanine)2-amino-6,9-dihydro-1H-purin-6-one

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:16235
ChEMBL:CHEMBL219568
EPA DTXSID:DTXSID9052476
PubMed:36176197
PubMed:27469509
PubMed:26010525
PubMed:23101657
PubMed:23094695
PubMed:23086183
PubMed:23059534
PubMed:23057664
PubMed:23045080
PubMed:23032709
PubMed:23031469
PubMed:23028689

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 73-40-5

1 total

Annex

Entry

113

CI 75170

2-Amino-1,7-dihydro-6H-purin-6-one

200-799-8

How CAS 73-40-5 is used on this site

CAS 73-40-5 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares 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 73-40-5 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 73-40-5 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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Tools & next steps

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