CAS Registry Number
A unique identifier assigned by the Chemical Abstracts Service (CAS) to every chemical substance described in the open scientific literature, enabling precise identification and tracking across databases and regulatory systems.
What is a CAS Registry Number?
A CAS Registry Number is a unique numerical identifier assigned by the Chemical Abstracts Service (CAS), a division of the American Chemical Society, to every chemical substance described in the scientific literature. It ensures unambiguous identification of chemicals, regardless of naming conventions or synonyms. The number is typically formatted as a hyphenated sequence (e.g., 7732-18-5 for water), with the last digit serving as a check digit to verify its validity.
Why is it important in chemical procurement and regulation?
In B2B procurement, lab operations, and regulatory compliance, CAS numbers are essential for ensuring the correct chemical is sourced, tested, and documented. They are used in safety data sheets (SDS), regulatory submissions (e.g., REACH, TSCA), and quality control (e.g., CoA, HPLC, GC-MS). Regulatory bodies such as the EU’s ECHA and the US EPA rely on CAS numbers to track substances across jurisdictions, ensuring consistency in hazard classification and risk assessment under frameworks like GHS.
How is it used in research and quality assurance?
Researchers and quality assurance teams use CAS numbers to cross-reference chemical data across databases (e.g., PubChem, ChemSpider), validate analytical results (e.g., NMR, HPLC), and ensure reproducibility. In pharmaceuticals, CAS numbers are critical for compliance with pharmacopoeial standards (USP, BP, EP) and for tracking active pharmaceutical ingredients (APIs) and excipients.
Related concepts
CAS Registry Numbers are often used alongside other identifiers such as IUPAC names, SMILES, InChI, and molecular formulas. They are integral to chemical data management systems and are required in regulatory documentation under ISO, REACH, and TSCA.