InChI FAQ's
Who or what is IUPAC?
The International Union of Pure and Applied Chemistry (IUPAC) exists to advance the worldwide aspects of the chemical sciences and to contribute to the application of chemistry in the service of mankind. As a scientific, international, non-governmental and objective body, IUPAC can address many global issues involving the chemical sciences.
What is an InChI?
The number of known chemical substances runs into many tens of millions; however conventional names are not best suited to the age of information technology, and IUPAC, in collaboration with the US National Institute of Standards and Technology (NIST), has developed the machine-readable International Chemical Identifier (InChI), an open-source identifier algorithmically generated from a two-dimensional graphical structure. This contains full structural information and can be converted back into the original structure.
What is an InChIKey?
Recognising the fact that the full InChI character string is not best suited to all types of electronic manipulation IUPAC and NIST have also developed a short fixed-length identifier, derived algorithmically from InChI and known as InChIKey. Although this version of the identifier does not itself contain information about chemical structure, it
* facilitates web searching
* allows development of a web-based InChI lookup service as described above
* permits an InChI representation to be stored in fixed length fields
* makes chemical structure database indexing easier
* allows verification of InChI character strings after network transmission.
The InChI/InChIKey descriptor is equivalent to a Digital Object Identifier (DOI) for chemicals and is transforming the ability of the chemical community to discover and link chemical, biochemical, and biomedical information and data via the internet.
So why do we need an InChI Resolver?
Whereas the InChI itself contains the chemical structure of the compound, the InchIKey cannot itself be used to derive the compound. If the InChI and InchIKey are published together, there is no ambiguity, but to avoid confusion there is a need for an InchIKey resolver, to allow anyone to submit an InchIKey and have returned the full InChI which describes the compound. InChI generation can be done in different ways, and an agreed 'standard' generation protocol is imminent.
