Meanings of chemical classification in English

A chemical classification of alkaloids is difficult on account of their complex constitution.

(Arranged in Groups according to the Chemical Classification in Watts' 'Dictionary of Chemistry.')

The relevant compounds and herbal extracts with anti-Parkinsonian activities were included and analyzed according to their chemical classifications or biological activities.

A Standard MedDRA Query (SMQ) for vasculitis was used and vaccine types were categorized using the Anatomical Therapeutic Chemical classification system.