CAS numbers, also known as CAS Registry Numbers or CAS RNs, are unique identifiers assigned to chemical substances by the Chemical Abstracts Service (CAS), a division of the American Chemical Society (ACS). CAS numbers are used to provide a standardized and unambiguous way of identifying and cataloging chemical substances.
CAS numbers consist of a series of digits separated by hyphens, with the first part typically containing up to seven digits, the second part containing two digits, and the final digit serving as a check digit. For example, the CAS number for water is 7732-18-5.
CAS numbers are widely used in scientific literature, databases, regulatory documentation, and chemical product catalogs. They help researchers, chemists, regulatory authorities, and other stakeholders accurately identify and track specific chemical substances, ensuring clarity and consistency in communication.
The assignment of CAS numbers is a meticulous process performed by CAS, which maintains the CAS Registry, a comprehensive and authoritative database of chemical substances. Each CAS number is unique to a specific substance and remains the same regardless of any changes in nomenclature or naming conventions.
CAS numbers provide a valuable tool for researchers and professionals in the chemical industry, enabling them to access extensive information about chemical substances, including their structures, properties, uses, and safety data.