CAS Numbers
CAS (Chemical Abstracts Service) Registry Numbers (often referred to as CAS RNs or CAS Numbers) are the unique identifiers for pure chemicals. Mixtures are usually not assigned CAS numbers.
A Registry Number itself has no inherent chemical significance but provides an unambiguous way to identify a chemical substance or molecular structure when there are many possible systematic, generic, proprietary, or trivial names.
While not commonly used in shipping, the CAS number may be found on containers and Material Safety Data Sheets (MSDS) and is used by many more detailed references as an indexing number. It is provided as another positive identifier and to allow quick reference to other databases.
[ CAS is a division of the American Chemical Society, located
in Columbus, Ohio. CAS is the producer of the largest and most comprehensive
databases of chemical information. The principal databases are the Chemical
Abstracts (CA) which contains over 18 million document records from the chemical
journal and patent literature, and Registry which contains over 36 million substance
records. ]