The same substance can have many names: an international non-proprietary name, a systematic chemical name, the developer's codes and brand names. The CAS number resolves that confusion: it is a figure in the format XXXXXXX-XX-X that corresponds to a single registered substance.
The last digit is a check digit calculated from the others, which makes it possible to detect transcription errors. For peptides, different salts (acetate, trifluoroacetate) or modified variants can have their own CAS numbers, different from that of the base form.
It is a reference datum, not a quality one: a correct CAS number on a label does not guarantee that the vial contains that substance or that it is pure. Only the batch analyses can show that.
The CAS number is used to cross-check a data sheet against public databases (PubChem, literature, regulation) and confirm that formula, molecular weight and sequence belong to the same molecule.
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Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).