In shortA CAS number (CAS Registry Number) is an internationally used number that uniquely identifies a chemical substance. Because it is unaffected by naming variations, it serves as a “common language” for ingredient sourcing, regulatory checks, and cross-referencing safety information.
What a CAS number is
A CAS number is a unique registry number assigned to a chemical substance by the Chemical Abstracts Service. One substance corresponds to one number, so you can tell whether differently named materials are the same substance. Note that salts and hydrates—different forms—are assigned different CAS numbers.
Why it matters in sourcing
- Confirming substance identity (same substance even if names differ)
- Cross-referencing regulatory and safety data (regulated status, SDS, etc.)
- Preventing ordering errors (does it match the intended form / salt)
Cautions
Plant extracts and mixtures may not have a single CAS number. Also, the same component can have different CAS numbers for hydrochloride, sodium salt, hydrate, and other forms, so always confirm that the intended form matches the CAS. FONTIA’s catalog publishes the CAS number for each ingredient.
FAQ
Does having a CAS number guarantee quality?
No. A CAS number is an identifier of the substance; quality is confirmed with the spec sheet and COA. It tells you “what substance,” not “how good.”
Do extracts have CAS numbers?
A standardized extract may have a CAS number, while a mixture may not have a single CAS number.
Why does the same component have multiple CAS numbers?
Because different forms—salts, hydrates, optical isomers—are assigned different numbers.