Last update 11 July 2017
CAS Numbers are assigned by the Chemical Abstracts Service (CAS), a division of the American Chemical Society. The CAS Registry database is maintained by CAS and contains the authoritative and internationally recognised list of all CAS Numbers and their chemical associations.
Chemicals on AICS are listed primarily by their CAS RN and CAS name.
What is a CAS Registry Number?
A CAS RN is a unique and specific identifier assigned to 1 chemical substance. CAS RNs can also be assigned to specific mixtures of chemicals.
Why are CAS numbers relied upon?
CAS Registered Numbers and their associated CAS names are relied upon by NICNAS as they are:
- internationally recognised
- are unique numbers
- an accurate source of chemical information
- a means of verifying a chemical identity
- able to be validated quickly
What does a CAS registry number look like?
A CAS RN contains up to 10 digits which are divided by hyphens into 3 parts.
For example, the CAS number for coconut oil is 61788-47-4
From the left, the first part of the number has 2 to 7 digits and the second part has 2 digits. The final part consists of a single check digit.
The check digit is mathematical calculated used to validate a CAS Registry Number.
How do I find out a CAS name and number?
The CAS Inventory Expert Service is a CAS Registry Number lookup service with associated fees. With this service you can liaise directly with CAS experts to obtain CAS names and CAS RNs. It also includes the option of assigning a CAS name only, without a corresponding CAS RN.
CAS also has a free web resource called Common Chemistry which lists CAS Registry Numbers for about 7,900 chemicals of widespread general public interest.
While not a comprehensive CAS Registry Number lookup service, Common Chemistry does provide a way to quickly and easily find names or CAS Registry Numbers for chemicals of general interest.
How do I get a CAS number assigned?
CAS Client Services offers you several options for confirming and assigning CAS Registry Numbers and obtaining CA Index Names.