Home

CAS-Nummern

CAS-registry number

International designation standard for chemical substances of all kinds. For each chemical registered in the CAS database, there is a unique CAS number. Attention: CAS numbers are not assigned for mixtures, but for pure substances.

What does CAS stand for?

CAS stands for Chemical Abstracts Service. It is an institution managed by the American Chemical Society.

How are they formed?

CAS numbers consist of three number blocks separated by two hyphens. The first block can contain up to seven digits, the second block consists of two digits. CAS numbers are given in ascending order and contain no internal order.

How are they assigned?

CAS numbers have been awarded since 1965 by the Chemical Abstracts Service. The use of the CAS registry database, which refers to any chemical structure using the CAS number, is subject to a charge.

What does the CAS number tell me?

Often, at first glance, it is not possible to see whether items from different suppliers are the same product. Just by the name (keyword trivial names, long lasting IUPAC names, other language names) a statement is often not possible. Even the empirical formula is not a solution since it can be identical for several substances and further physical parameters have to be used for the analysis The CAS number clearly indicates which chemical compound is involved. It distinguishes between the different salt forms (sodium salt / potassium salt / monohydrate / decahydrate / hydrochloride etc.) and between stereoisomers. For non-chemists, too, the CAS number therefore allows a simple and unambiguous assignment / identification of the chemical substance offered.

Where are the limits of the CAS number? What am I not experiencing?

Although the CAS number indicates exactly which chemical substance is involved. However, it is not sufficient to distinguish different qualities or purities. So regardless of whether it is DMSO "pure EP", "for cell culture", "for molecular biology" or "for analysis" - the CAS number is identical in all cases. In addition, it can sometimes happen that a substance has not (yet) been assigned a CAS number. In rare cases one finds two numbers for one and the same substance. But these are really the exceptions.

Example for a neoLab search

With the usage of the CAS Number, all chimcals can be found in the online shop.

Conclusion

The article search based on the CAS number usually leads to a result faster than the search for product names. As soon as all matches are displayed, the fine tuning is done by selecting the appropriate quality.

Further information on CAS numbers

European database for CAS numbers Weblink >>

Additional information on Wikipedia.com Weblink >>

Additional information from Chemie.com Weblink >>