CAS Number Lookup and Chemical Identifier Database
The CAS number lookup is one of the key features for identifying a chemical substance, browsing a Safety Data Sheet, checking supplier information or even starting a regulatory assessment.
RRMA CAS Identifier Database — Search for CAS numbers in the RRMA CAS Identifier Database to find corresponding information on identified chemical substances.
Whether you are a regulatory professional, manufacturer, importer, researcher, supplier or student the CAS identifier for a chemical helps to distinguish between individual chemical substances and their many different names.
CAS Identifier
Easily identify chemical substances using their unique CAS numbers, ensuring compliance with industry and regulatory
standards. Stay ahead in chemical management with accurate substance identification.
What Is a CAS Number?
In chemistry, a CAS Registry Number (CAS number, CAS RN) is a unique identifier for a chemical in CAS REGISTRY.
The commonly used full form of CAS number is:
Chemical Abstracts Service Registry Number
Chemicals can be identified by many names: systematic names and common names and even manufacturers’ trade names and suppliers’ names and the names used by researchers and in databases and in regulations. This means there is considerable potential for confusion – sometimes serious – between apparently different names which in fact denote the same chemical.
In identifying a chemical, the CAS number serves as a reference or constant that helps to distinguish a single chemical from others even when referred to by different names.
For example:
Acetone
CAS Number: 67-64-1
CAS numbers are common identifiers used in databases, safety information, scientific publications, government regulations, product formulations, and in documenting supplier and customer information within a supply chain.
Why Are CAS Numbers Important?
The identifier for a chemical in the CAS database serves the purpose of a name for the chemical and in many cases is more sufficient than the name for the identification of a chemical.
They are commonly used for:
Safety Data Sheets
In SDS composition, CAS numbers for the chemical ingredients are indicated in the substance identification section.
Regulatory Compliance
CAS numbers are commonly used when searching national and regional chemical inventories as well as a number of chemical and bioscience related databases.
Having a CAS number does not automatically mean that the corresponding chemical is registered, approved, etc. under a certain chemical regulation.
Chemical Inventory Management
When managing a large number of substances CAS identifiers can be used to distinguish between chemicals of similar or alternate names.
Supply Chain Communication
Manufacturers, importers, distributors and other downstream users of chemicals can use CAS numbers to ensure that substance identity is communicated consistently.
Research and Scientific Data
In many scientific databases, CAS numbers are used for searching.
What Does a CAS Number Look Like?
A CAS Registry Number is a 10 digit number which might be separated by up to two hyphens into three parts.
Example:
64-17-5
The final digit of a CAS number is a check digit which is mathematically correct for the correct numerical structure of the CAS number.
A number is always correct formatted, but that does not necessarily mean it is the CAS number for the chemical you are looking for.
Cross check with associated chemical name and other substance information (e.g. chemical formula, structure, etc.).
How to Search a CAS Number
If you already know the CAS number of a substance, use the following steps.
Step 1:Enter the CAS Number
Enter the complete identifier into the RRMA CAS number lookup tool.
Step 2: Review the Chemical Information
Verify the chemical name(s) and available substance information (e.g. hazard statements,Danger Statements) for the CAS number searched.
Step 3: Compare Supporting Documents
Where relevant, compare the search result with:
- Safety Data Sheet
- supplier specification
- Certificate of Analysis
- chemical name and synonyms
- molecular formula
- composition information
- regulatory inventory information
Step 4: Verify Before Regulatory Use
Even when documents contain different CAS numbers or even apparently different identities, they can be verified against each other to determine if they can be used for submissions or for compliance decisions.
How to Check a CAS Number
Check a CAS number by itself is not enough to verify its correctness.
Review:
- CAS number format
- chemical name
- synonyms
- molecular formula
- chemical structure
- supplier documentation
- regulatory database information
For important decisions concerning your company related to above mentioned points, you must cross check substance identity from appropriate sources.
Third party databases are useful for conducting research; however, assignment and verification of a CAS Registry Number is associated with CAS.
How to Find a CAS Number
Do you know the chemical name but not the CAS number? Search for a CAS number in a CAS number database or in a chemistry database.
Start with information such as:
- chemical name
- IUPAC name
- common name
- synonyms
- molecular formula
- chemical structure
- SDS information
- supplier documentation
- Extra care may be needed when identifying:
- polymers
- reaction products
- UVCB substances
- salts
- hydrates
- stereoisomers
- petroleum substances
- biological extracts
Compounds with similar names can have different CAS numbers if they are of different chemical structure.
CAS Database and CAS Number Database
A CAS database is a chemical database which contains substances in a CAS Registry Database, organized by their respective CAS Registry Numbers.
The official database for CAS Registry Numbers is CAS REGISTRY.
Other scientific databases and even some government agencies use CAS numbers to search for chemical information on the web, but typically they do not assign CAS numbers as part of their identifiers.
Examples include:
RRMA CAS Identifier
RRMA provides a simple way to find out the CAS number for a chemical as well as to start your chemical identification research with information relevant for regulatory purposes.
CAS Common Chemistry
CAS Common Chemistry is a free tool to look up information on commonly encountered chemical substances.
NIST Chemistry WebBook
The NIST Chemistry WebBook allows you to search the entire Chemistry WebBook for chemical and physical property information, among other things, by using a CAS Registry Number as a search term.
EPA CompTox Chemicals Dashboard
The US EPA CompTox Chemicals Dashboard allows users to search for chemicals using a variety of identifiers including chemical names and CAS numbers. An EPA CAS number search can therefore be useful when users want to connect chemical identity with available EPA chemical information.
An EPA CAS number search can be of value when trying to associate chemical identity with EPA chemical information.
How to Get a CAS Number for a New Chemical
Searching for an existing CAS number and obtaining a new CAS number are two very different things.
If your chemical is listed in CAS REGISTRY (and it usually is) then you will want to search for the CAS RN of the chemical that you are interested in.
A request for official assignment of a CAS RN must be made through CAS Registry Services for a substance that is new and does not have a CAS RN yet.
Information that may be needed to identify a new substance to receive a CAS Registry Number can vary by type of substance.
- chemical structure
- chemical name
- molecular formula
- stereochemistry
- composition
- manufacturing process
- reactants
- impurities
- analytical information
Complex mixtures may require significantly more information to establish adequate identity than simple chemicals.
RRMA does not assign official CAS Registry Numbers. The RRMA CAS Identifier is a tool that enables lookup of chemical information.
CAS Numbers and Regulatory Compliance
A CAS identifier is important in regulatory work. However, it is only one part of a full compliance assessment.
Finding a substance in a CAS number database does not automatically confirm that it is:
- registered under a chemical regulation
- listed on a national inventory
- permitted for manufacture or import
- exempt from notification
- unrestricted
- correctly classified
- compliant with SDS requirements
The key to determining the correct requirements is to establish the countries or markets in which the chemical will be used.
CAS Number, EC Number and UN Number
Different identifiers serve different purposes.
Identifier Main Purpose
CAS Number Identifies a specific chemical substance
EC Number Used for substances within European chemical systems
UN Number Identifies dangerous goods for transport
InChI Structure-based chemical identifier
DTXSID EPA DSSTox substance identifier
Note: chemical can have several identifiers, and these identifiers must not be used interchangeably.
Frequently Asked Questions
What is a CAS number?
A CAS number is a special identification number given to chemicals when they are entered into the CAS REGISTRY of the Chemical Abstracts Service. It ensures that even when a chemical is referred to by several different names (synonyms), it can be identified as being the same substance.
What is the full form of CAS number?
The commonly used full form is Chemical Abstracts Service Registry Number.
How can I search for a CAS number?
Find a CAS number by entering the complete CAS number in a CAS number lookup or in a chemical database. Compare the substance information with the information on the associated SDS or supplier documentation.
How do I find a CAS number?
Most chemicals can be found in databases of chemical information by searching for the chemical name, or one of its many synonyms, or by searching for the formula or a line drawing of the chemical structure. In some cases more than one search may be needed to confirm the identity of very complex substances.
How can I check whether a CAS number is correct?
A correctly formatted CAS number does not guarantee that a substance has been correctly identified. Always check a CAS number against the chemical name, molecular formula, substance structure, alternative names (synonyms) and confirm with the supplier’s documentation (SDS).
What is a CAS number register?
Many people refer to a CAS number register. Such a register is generally understood to mean the CAS REGISTRY containing all chemical substances with their corresponding CAS Registry Numbers.
Is every CAS number unique?
Different chemical forms of a substance (such as salts or hydrates) as well as different stereoisomers receive different CAS Registry Numbers. To get a CAS number for a new substance, once it has been confirmed that the substance has not previously been described, a request for official assignment can be submitted to CAS Registry Services.
Does RRMA assign CAS numbers?
No, RRMA does not assign CAS numbers. RRMA is a CAS number lookup and chemical information resource. The assignment of CAS Registry Numbers for substances is performed by CAS.
What is an EPA CAS number search?
The EPA CompTox Chemicals Dashboard allows users to search for chemical substances using different chemical identifiers, including CAS Numbers. When a CAS Number is searched, the results link the identified substance with relevant chemical information available in EPA databases.
Important points to understand
- A CAS Number is a unique identifier assigned by Chemical Abstracts Service (CAS) to a specific chemical substance listed in its database of reported chemicals.
- Having a CAS Number does not mean that the substance is registered, approved, or regulated under any specific law or regulation.
- A CAS Number only confirms the identity of a chemical substance; it does not indicate compliance status or regulatory registration.
If a CAS number search does not provide results
Possible reasons and actions to take include:
| Reason | Action to take |
|---|---|
| The CAS Number may have been entered incorrectly | Verify the CAS Number against the SDS, supplier documentation, labels, or product catalogs. |
| The CAS Number may contain a typing error from the source document | Cross-check the number with reliable supplier information. |
| The substance may not have sufficient identity information available | Search using the chemical name or synonyms. |
| The substance may require additional identity verification | Provide further substance details, especially for complex substances. |
Note on Complex Substances:
For complex substances (such as UVCBs, mixtures, or substances with variable compositions), a CAS Number alone may not always be sufficient to confirm the exact substance identity. Additional information may be required for Substance Identity Verification.
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