CAS number (chemical identifier)
A unique numeric identifier such as “7732-18-5” (water) assigned to each chemical substance by the Chemical Abstracts Service of the American Chemical Society. Because the same substance can be sold under many trade and local names, it is the most reliable way to avoid confusion in sourcing; SDSs, REACH registrations, customs and restricted-substance lists all work by CAS number. Mixtures have no single CAS number – their components are listed separately. In the EU the EC (EINECS) number is also used.
Related terms
REACH and KKDİK (chemical registration)
EU Regulation 1907/2006, which requires every substance manufactured in or imported into the EU above 1 tonne a year to be registered with the European Chemicals Agency (ECHA) – “no data, no market”. A non-EU supplier can register through an Only Representative; otherwise the obligation falls on the importer. Türkiye’s equivalent is the KKDİK Regulation, and Korea (K-REACH), China and the UK (UK REACH) run similar systems. Buyers should ask for the registration number and whether the substance contains SVHCs (substances of very high concern).
Safety data sheet (SDS / MSDS)
A document setting out, in 16 standard sections following the GHS, a chemical’s hazards and information on safe handling, storage, transport, personal protective equipment, first aid, firefighting, accidental release and disposal. It is mandatory for hazardous substances under REACH in the EU and similar laws elsewhere, and must be supplied in the recipient’s language. Carriers and customs rely on section 14 for dangerous-goods classification and the UN number.
Chemical purity grades (technical, food, pharma, analytical)
The same chemical is sold in different purity and impurity limits at different prices. Technical or industrial grade is for general manufacturing; food grade (E-number additives, FCC or JECFA specifications, heavy-metal limits) for food and feed; pharmacopoeia grade (USP, EP/Ph. Eur., BP, JP) for medicines and some cosmetics, produced under GMP; analytical or reagent grade (ACS, AR, HPLC) for laboratories. Using a lower grade in place of a higher one breaches regulations, so the grade and reference specification must be written on the order and the COA.