The origin of impurities
Impurities increase on the one side from known synthetical procedures, on the other side from modifications because of economic reasons or patents.
Because of institutional conditions all analytical compounds over 0.1 area % HPLC (in year 2004) have to be declared. This includes active substances, excipients, known and unknown impurities.

A big amount of active substances and of known impurities is available for example as CRS- or USP- Standards.

Moreover Phytochem® produces unknown impurities for individual customer needs, documented as a Primary Standard in the RMF Format.