Chemicals & safety
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.
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.
Dangerous goods transport (UN number, IMDG, ADR, IATA)
Flammable, corrosive, toxic, oxidising or environmentally hazardous substances are governed by mode-specific rules: the IMDG Code at sea, ADR by road, RID by rail and IATA DGR by air. Each substance is identified by a four-digit UN number (e.g. UN1823 sodium hydroxide, solid), a hazard class (1–9) and a packing group (I–III), all given in section 14 of the SDS. UN-approved packaging, class labels, a dangerous goods declaration and trained staff are compulsory; freight and insurance cost more than for general cargo, and some ships and ports refuse certain classes.
GHS / CLP classification and labelling (pictograms, H and P statements)
The UN Globally Harmonized System (GHS) classifies the physical, health and environmental hazards of chemicals by the same criteria worldwide; in the EU it is applied through the CLP Regulation. Labels carry the relevant red-bordered pictograms (nine in total), the signal word “Danger” or “Warning”, hazard (H) statements such as H314 “causes severe skin burns” and precautionary (P) statements. The classification is given in section 2 of the SDS, must match the package label, and labels must be in the language of the destination country.
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).
Shelf life, retest date and storage conditions
The period during which a raw material keeps its specification values when stored under the recommended conditions. Vitamins, enzymes, peroxides, monomers, reactive chemicals and some oils degrade over time, so the production date and the expiry or retest date should appear on the COA and label. Storage conditions – temperature range, humidity, light, storage under inert gas, closed packaging – are given in section 7 of the SDS. A clause such as “at least 75 % of shelf life remaining on delivery” is a common protection against old stock.