In 1975, the WHO Expert Committee on Specifications of
Pharmaceutical Preparations recommended "General guidelines for
the establishment, maintenance and distribution of chemical
reference substances" (1).1 At that time these general
guidelines were aimed at fostering greater collaboration and
harmonization among various national and regional authorities
responsible for collections of chemical reference substances.
This aim is still relevant. The guidelines were initially drawn
up for particular use by the WHO Collaborating Center for
Chemical Reference Substances in Sweden, which provides
International Chemical Reference Substances (ICRS). These
substances are primarily intended for use with pharmacopoeial
monographs included in The international pharmacopoeia (2). 1
The term chemical reference substances, as used in this text,
refers to an authenticated uniform material that is intended for
use in specified chemical and physical tests, in which its
properties are compared with the properties of a product un